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1
Sithole, Thandiwe. "Elevated Temperature Basic Oxygen Furnace Slag Stabilisation of Desilicated Foundry Sand". Key Engineering Materials 953 (25.08.2023): 105–12. http://dx.doi.org/10.4028/p-onlwu9.
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This study presents the use of Basic Oxygen Furnace slag (BOFS) as a stabilizer for disilicated waste foundry (DWF) sand and therefore provides an opportunity for high-volume use of waste material for low-cost, low-volume building and construction material. DWF was stabilized with BOFS to 40 %. The effect of composite moisture content, BOFS content, curing time and curing temperature was studied. A 50:50 DWF: BOFS composite cured at 80 °C for 96 h had the highest unconfined compressive strength (UCS) of 7.83 MPa, a 15.5 % water absorption after a 24 h soak with a corresponding 20.5 % reduction in UCS. The green specimen (70:30) was then used to stabilize expansive soil. The formation of hydration products was responsible for the strength gain in the stabilized DWF specimens. It was concluded that BOFS was successful in stabilizing DFS. The stabilised DWF for ASTM C34-13, C129-14a and South African standards (SANS227: 2007).
2
Falciglia, Pietro Paolo, Abir Al-Tabbaa i Federico G. A. Vagliasindi. "DEVELOPMENT OF A PERFORMANCE THRESHOLD APPROACH FOR IDENTIFYING THE MANAGEMENT OPTIONS FOR STABILISATION/SOLIDIFICATION OF LEAD POLLUTED SOILS". JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT 22, nr 2 (19.03.2014): 85–95. http://dx.doi.org/10.3846/16486897.2013.821070.
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Two soils spiked with lead at different rates were stabilised/solidified using Portland cement and fy ash at different soil:binder ratios, and tested for their setting time, unconfined compressive strength, leachability and durability. A performance threshold approach was used in order to identify optimal management options for the products of the S/S treatment. Results show that soil texture, percentage of binders and lead concentration play an important part in the treatment, significantly influencing the performance of the resulting products in terms of curing, compressive strength and durability. Pb soil concentrations higher than 15000 mg kg-1 were found to heavily reduce the applicability of the treatment requiring the maximum amount of binder in order to satisfy the performance criteria. Te performance of sandy soils was shown to be limited by setting time and UCS features due to the retardation of the hydration reactions and also by its leaching behaviour, whereas for silt-clayey soils the critical parameter is the mechanical resistance.
3
Jeremiah, Jeremiah J., Samuel J. Abbey, Colin A. Booth i Anil Kashyap. "Geopolymers as Alternative Sustainable Binders for Stabilisation of Clays—A Review". Geotechnics 1, nr 2 (29.11.2021): 439–59. http://dx.doi.org/10.3390/geotechnics1020021.
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The need to transit to greener options in soil stabilisation has revamped research on the use of industrial and agricultural by-products in order to cut down on the current carbon footprint from the use of ordinary Portland cement (OPC) and lime related binders for the treatment of problematic soils. This study is a review on the use of geopolymers constituted by alkali activation of several industrial wastes such as pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS), metakaolin (MK), glass powder (GP), palm oil fuel ash (POFA), silica fume (SF), rice husk ash (RHA), volcanic ash (VA), and marble powder (MP) for the stabilisation of weak clays. The performance of stabilised clays as subgrade and subbase materials for road pavement construction was evaluated by comparing the 7 day UCS of the treated clays with the strength requirement for stabilised materials as outlined in BS EN 16907-4. The result of the study shows that geopolymers can be employed in improving the engineering properties of problematic clays to meet practical applications. Strength improvement was observed in the stabilised clays with increased precursor content, molarity of alkaline activator, and curing period.
4
Xing, Guoqi, Lijun Zhang, Wei Xuan, Yueyue Pan, Yue Zhao i Bing Zhang. "Influence of Alkaline Activators on Unconfined Compressive Strength of Saline Soils Stabilised with Ground Granulated Blast Furnace Slags". Advances in Civil Engineering 2021 (23.11.2021): 1–13. http://dx.doi.org/10.1155/2021/8893106.
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To mitigate the environmental impact induced by CO2 emissions and nonrenewable resource consumption, which are typically associated with Portland cement production, ground granulated blast furnace slags (GGBSs) are usually added to the cement. In this study, the stabilisation effect of alkali-activated GGBS on saline soil and the hydration products of alkali-activated GGBS were investigated by unconfined compressive strength tests and scanning electron microscopy, respectively. The results show that Ca(OH)2 and NaOH as alkaline activators for GGBS significantly improve the unconfined compressive strength of saline soils. This strength is also enhanced by Na2SO4; however, the increase is considerably less than that provided by Ca(OH)2 and NaOH. In contrast, Na2CO3 is not a suitable alkaline activator for GGBS and has no significant effect on the unconfined compressive strength of saline soils. The study results further show that the morphology of hydration products varies because of the different alkaline activators involved in the hydration reaction with GGBS in saline soils.
5
Cristelo, Nuno, Jhonathan Rivera, Tiago Miranda i Ana Fernández-Jiménez. "Stabilisation of a Plastic Soil with Alkali Activated Cements Developed from Industrial Wastes". Sustainability 13, nr 8 (18.04.2021): 4501. http://dx.doi.org/10.3390/su13084501.
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The development of alternative materials for the construction industry, based on different types of waste, is gaining significant importance in recent years. This is mostly due to the need to increase sustainability of this heavily polluting activity, thus mitigating the dependence on, for instance, Portland cement. The present paper is related to the development of an alkaline activated cement (AAC) exclusively fabricated from industrial by-products (both precursor and activator). Coal combustion fly ash, a common residue from thermoelectric powerplants, and glass waste, from the manufacture of ophthalmic lenses, were used as precursors. These precursors were activated with a recycled alkaline solution, resulting from the cleaning of aluminium extrusion dies, instead of the more common commercial reagents usually applied for this type of binder. Several pastes were studied, combining the precursor and alkaline solution in different proportions. When the most-performing cements were defined, they were used to stabilise a cohesive soil. The experimental procedure and subsequent analysis were designed based on a Response Surface Methodology model, considering the Activator/Solids and Soil/Precursor ratios as the most relevant variables of the stabilisation process. It was observed that, depending on the type of alkaline cement used, there was an optimum precursor and activator contents to optimise the mechanical properties of the stabilised soil. The reliability of this prediction was especially dependent on the type of precursors and, also, on their respective dissolution process right before the homogenization with the soil, under the working conditions available.
6
Luo, Zhengdong, Biao Luo, Yufei Zhao, Xinyu Li, Yonghua Su, He Huang i Qian Wang. "Experimental Investigation of Unconfined Compression Strength and Microstructure Characteristics of Slag and Fly Ash-Based Geopolymer Stabilized Riverside Soft Soil". Polymers 14, nr 2 (13.01.2022): 307. http://dx.doi.org/10.3390/polym14020307.
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To solve the issues of insufficient early strength of cement stabilized soil and high resource cost, high reduction cost, and high environmental cost induced by the application of cement, the slag and fly ash-based geopolymer was adopted as the stabilizer to treat riverside soft soil. This study mainly investigated the effects of stabilizer content, slag-to-fly ash ratio, and alkaline activator content on the strength of geopolymer stabilized soils with different curing ages. Unconfined compressive strength (UCS), scanning electron microscope (SEM), and X-ray energy spectrum analysis (EDS) tests were carried out. The results show that the stabilizer content, slag–fly ash ratio, and alkaline activator content have a decisive influence on the UCS of geopolymer-stabilized soil. The mix-proportions scheme of geopolymer stabilized riverside soft soil, with a geopolymer content of 15%, a slag–fly ash ratio of 80:20, and an alkaline activator content of 30%, is considered optimum. It is proven by SEM that the uniformly distributed gelatinous products formed in the geopolymer-stabilized soil bind the soil particles tightly. Moreover, the EDS analysis confirms that the gelatinous products are mainly composed of C-S-H gel and sodium-based aluminosilicate (N-A-S-H).
7
Shen, Xiao Ming, Zhan Guo Li, Da Huo i Hai Yan Zhao. "A Preliminary Study of Stabilizing Artificial Saline Sludge Using Compound Stabilizer". Advanced Materials Research 450-451 (styczeń 2012): 343–47. http://dx.doi.org/10.4028/www.scientific.net/amr.450-451.343.
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There is large-area saline sludge which should be stabilized in China. In this experiment, cementitious component (cement), alkaline component (Ca(OH)2) and expansive component (sulfuraluminate cement or gypsum) were used as compound stabilizer with different combinations to stabilize artificial saline sludge, then the unconfined compressive strength of stabilized soil samples was determined, and the hydration products of the stabilized soil were analyzed by XRD, the stabilizing mechanism and the required hydrate species of stabilized soil were preliminary explored. The results show that the unconfined compressive strength of stabilized soil increases gradually with the increase of the cement content; when partial cement replaced by right amount of CH, the strength reaches the maximum and higher than that of soil-cement; the use of sulfuraluminate cement plaster as expansive component for stabilizing saline sludge has a relatively good overall affect compared to the gypsum; possible reasons for these results were speculated at the same time.
8
Parsons, Robert L., i Justin P. Milburn. "Engineering Behavior of Stabilized Soils". Transportation Research Record: Journal of the Transportation Research Board 1837, nr 1 (styczeń 2003): 20–29. http://dx.doi.org/10.3141/1837-03.
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Stabilization of soils is an effective method for improving soil properties and pavement system performance. For many soils, more than one stabilization agent may be effective, and financial considerations or availability may be the determining factor on which to use. A series of tests was conducted to evaluate the relative performance of lime, cement, Class C fly ash, and an enzymatic stabilizer. These products were combined with a total of seven different soils with Unified Soil Classification System classifications of CH, CL, ML, and SM. Durability testing procedures included freeze–thaw, wet–dry, and leach testing. Atterberg limits and strength tests also were conducted before and after selected durability tests. Changes in pH were monitored during leaching. Relative values of soil stiffness were tracked over a 28-day curing period using the soil stiffness gauge. Lime- and cement-stabilized soils showed the most improvement in soil performance for multiple soils, with fly ash–treated soils showing substantial improvement. The results showed that for many soils, more than one stabilization option may be effective for the construction of durable subgrades. The enzymatic stabilizer did not perform as well as the other stabilization alternatives.
9
Liu, Hailong, Jiuye Zhao, Yu Wang, Nangai Yi i Chunyi Cui. "Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil". Sustainability 13, nr 4 (20.02.2021): 2295. http://dx.doi.org/10.3390/su13042295.
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Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.
10
Yi, Yaolin, Kaiwen Lu, Songyu Liu i Abir Al-Tabbaa. "Property changes of reactive magnesia–stabilized soil subjected to forced carbonation". Canadian Geotechnical Journal 53, nr 2 (luty 2016): 314–25. http://dx.doi.org/10.1139/cgj-2015-0135.
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A reactive magnesia (MgO) was used to stabilize a natural soil; the MgO-stabilized soil was subjected to forced carbonation with pressurized gaseous CO2 in a triaxial cell set-up. The change of physical properties, including bulk density, moisture content, dry density, specific gravity, and porosity, of the stabilized soil during carbonation was studied. The mechanical and microstructural properties of the carbonated MgO-stabilized soil were also investigated through unconfined compressive strength (UCS) test, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results indicated that the carbonation of MgO-stabilized soil consumed CO2 and water, and produced expansive carbonation products; this consequently increased the dry density, and reduced the moisture content, specific gravity, and porosity of the stabilized soil. After being carbonated for only 1.5 h, the MgO-stabilized soil yielded remarkable strength, with UCS higher than that of the 28 day ambient cured Portland cement–stabilized soil, mainly due to the high binding effect of carbonation products and the low porosity of carbonated MgO-stabilized soil. The carbonated MgO-stabilized soil achieved a high degree of carbonation in a few hours (≤12 h), with the maximum CO2/MgO ratio in a range of 0.76–1.07.
11
Mashifana, Tebogo Pilgrene, Felix Ndubisi Okonta i Freeman Ntuli. "Geotechnical Properties and Microstructure of Lime-Fly Ash-Phosphogypsum-Stabilized Soil". Advances in Civil Engineering 2018 (2.09.2018): 1–9. http://dx.doi.org/10.1155/2018/3640868.
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The use of industrial waste as a potential stabilizer of marginal construction materials is cost effective. Phosphogypsum and fly ash are industrial wastes generated in very large quantities and readily available in South Africa. In order to explore the potential stabilization of vastly abundant expansive soil using larger quantity phosphogypsum waste as a potential modifier, composites with a mixture of lime-fly ash-phosphogypsum-basic oxygen furnace slag were developed. However because of the presence of radionuclide, it was necessary to treat the phosphogypsum waste with mild citric acid. The effect of the acid treatment on the geotechnical properties and microstructure of expansive soil stabilized with phosphogypsum-lime-fly ash-basic oxygen furnace slag (PG-LFA-BOF) paste was evaluated, in comparison with the untreated phosphogypsum. Expansive soil stabilized with acid-treated PG-LFA-BOF paste exhibited better geotechnical properties; in particular, the high strength mobilized was associated primarily with the formation of various calcium magnesium silicide and coating by calcium silicate hydrate and calcium aluminate hydrate. The soil microstructure was improved due to the formation of hydration products. The stabilized expansive soil met the specification for road subgrades and subbase. Stabilization of expansive soils with phosphogypsum, fly ash, and basic oxygen fly ash does not only improve engineering properties of soil but also provides a solution in relation to disposal and environmental pollution challenges.
12
Wu, Xue-Ting, Yi Qi, Jun-Ning Liu i Bin Chen. "Solidification Effect and Mechanism of Marine Muck Treated with Ionic Soil Stabilizer and Cement". Minerals 11, nr 11 (14.11.2021): 1268. http://dx.doi.org/10.3390/min11111268.
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In this study, an environmentally friendly ionic soil stabilizer (ISS) was adopted with combination of Portland cement to stabilize a marine muck. The macro and micro tests results demonstrated that the ISS was an effective stabilizer to improve the strength of marine muck when it was used combined with cement after adding the alkalizer NaOH. Except for the reduction in interlayer distance of clay minerals by ISS, Ca2+ and SO42− dissolved from ISS promoted the production of ettringite (AFt), pozzolanic and carbonation reactions of Portland cement in the presence of NaOH. Meanwhile, the hydration products of curing reaction notably agglomerated soil particles, which caused an obvious decrease of pores and a high increase of strength for solidified soils. Furthermore, this combination of stabilizers can not only save the dosage of cement, but also accelerate the solidification speed, decrease the cement setting time within 7 days to meet the curing requirements, and enhance the strength of solidified soils.
13
Yi, Yaolin, Martin Liska, Fei Jin i Abir Al-Tabbaa. "Mechanism of reactive magnesia – ground granulated blastfurnace slag (GGBS) soil stabilization". Canadian Geotechnical Journal 53, nr 5 (maj 2016): 773–82. http://dx.doi.org/10.1139/cgj-2015-0183.
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Reactive magnesia (MgO)-activated ground granulated blastfurnace slag (GGBS), with fixed GGBS dosages but varying MgO/GGBS ratios, was used for stabilization of two soils and compared with brucite (Mg(OH)2)-activated GGBS and hydrated lime (Ca(OH)2)-activated GGBS. A range of tests, including unconfined compressive strength testing, X-ray diffraction, and scanning electron microscopy, was conducted to study the mechanical, chemical, and microstructural properties of the stabilized soils, and then to investigate the mechanism of MgO–GGBS soil stabilization. Results indicate that the Mg(OH)2 had a minimal activating efficacy for GGBS-stabilized soil, while the reactive MgO yielded a higher activating efficacy than the Ca(OH)2. The activator–soil reactions in the stabilized soil slowed down the activating reaction rate for GGBS; this effect was less significant in MgO–GGBS-stabilized soil than in Ca(OH)2–GGBS-stabilized soil, and hence the GGBS hydration rate in the former was less reduced by the soil than the latter. The Mg2+ and OH− ions produced from MgO dissolution participated in the GGBS hydration reactions without precipitating Mg(OH)2. The common hydration products in all GGBS-stabilized soils were calcium silicate hydrate–like compounds. Additionally, hydrotalcite and calcite could be produced in MgO–GGBS- and Ca(OH)2–GGBS-stabilized soils, respectively, especially with a high activator/GGBS ratio.
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Wei, Mingli, Hao Ni, Shiji Zhou i Yuan Li. "Feasibility of Stabilized Zn and Pb Contaminated Soils as Roadway Subgrade Materials". Advances in Materials Science and Engineering 2020 (16.12.2020): 1–11. http://dx.doi.org/10.1155/2020/1025056.
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The authors have developed a new binder, KMP, which is made from oxalic acid-activated phosphate rock, monopotassium phosphate (KH2PO4), and reactive magnesia (MgO). This study explores the acid neutralization capacity, strength characteristics, water-soaking durability, resilient modulus, and pore size distribution of KMP stabilized soils with individual Zn, Pb, or coexisting Zn and Pb contaminants. For comparison purpose, Portland cement (PC) is also tested. The results show that KMP stabilized soils have a higher acid buffering capacity than PC stabilized soils, regardless of the soil contamination conditions. The water stability coefficient and resilient modulus of the KMP stabilized soils are found to be higher than PC stabilized soils. The reasons for the differences in these properties between KMP and PC stabilized soils are interpreted based on the stability and dissolubility of the main hydration products of the KMP and PC stabilized soils, the soil pore distribution, and concentration of Mg or Ca leached from the KMP and PC stabilized soils obtained from the acid neutralization capacity tests. Overall, this study demonstrates that the KMP is effective in stabilizing soils that are contaminated with Zn or Pb alone and mixed Zn and Pb contaminants, and the KMP stabilized soils are better suited as roadway subgrade material.
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Zha, Fusheng, Congmin Liu, Bo Kang, Long Xu, Chengbin Yang, Chengfu Chu, Chuang Yu, Wei Zhang, Jiwen Zhang i Zhenghong Liu. "Effect of Carbonation on the Leachability of Solidified/Stabilized Lead-Contaminated Expansive Soil". Advances in Civil Engineering 2021 (11.02.2021): 1–13. http://dx.doi.org/10.1155/2021/8880818.
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Lime, fly ash, and alkaline residue are used widely as effective binders to solidify/stabilize heavy metal-contaminated expansive soil. Carbonation, however, may influence the effectiveness of solidification/stabilization (S/S) by decomposing hydration products and decreasing pH, which would seriously damage the long-term durability of stabilized soils. This study focused on the variation of leaching characteristics of solidified/stabilized lead-contaminated expansive soils before and after accelerated carbonation under the leachant of pH 3 and 5 by the semidynamic leaching test. After semidynamic leaching, leaching indexes such as the effective diffusion coefficient (De), leachability index (Lx), and slope (rc) were used to reveal the ion leaching mechanism. The results indicated that the amount of Pb2+ and Ca2+ leached out under different pH conditions increased after carbonation, which confirmed that carbonate on solidified/stabilized lead (Pb) had a negative impact. Additionally, the De values of Pb2+ and Ca2+ varied in the range of 1.16E − 10 cm2/s to 1.71E − 07 cm2/s, which demonstrated that ion migration was low. The contaminated soil solidified by lime and AR could be used in “controlled utilization” as Lx was higher than 9, and the leaching process was controlled by a dissolution reaction according to the analysis of rc. Moreover, the strong acidic leachant (pH = 3) resulted in more ions leaching out and lower pH in leachate compared with a mildly acidic leachant. Finally, with literature and experimental results, we found that the main reason for the increase of lead ion filtration of the carbonation reduced the pH value of the matrix and made the hydration products denatured and decomposed.
16
Dai, Di, Jie Peng, Lanlan Bai, Gang Li i Hongmin Lin. "The Effect of Superabsorbent Polymer on the Resilient and Plastic Strain Behavior of Cemented Soil under Traffic Load". Polymers 14, nr 5 (25.02.2022): 929. http://dx.doi.org/10.3390/polym14050929.
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In road construction, a large number of excavated soils need to be treated with stabilizers. The addition of superabsorbent polymer (SAP) can improve the road performance of these stabilized soils. In order to predict roadbed deformation, dynamic triaxial tests were carried out on cemented soil containing SAP to investigate its resilient and plastic strain behavior. The effects of SAP content, cyclic stress ratio, and loading frequency on cement-stabilized soils with SAP were analyzed combined with the number of cycles. This study demonstrates how these influencing factors effect the resilient strain, dynamic elastic modulus, and accumulated plastic strain, which are crucial to better understanding the strain behavior of cement-stabilized soil with SAP. The results show that SAP can significantly improve the brittle failure characteristics and dynamic strength of cement-stabilized soil. Soil with higher SAP content possesses smaller accumulated plastic strain; with the increase in the cyclic stress ratio, the dynamic elastic modulus decreases significantly, whereas the accumulated plastic strain has the opposite trend. In addition, the lower frequency produces larger cumulative axial strain.
17
Tchakalova, Boriana, i Tzvetoslav Iliev. "Scanning electron microscopy investigation of loess soil stabilized with cement and natural zeolite". Geologica Balcanica 51, nr 1 (kwiecień 2022): 15–21. http://dx.doi.org/10.52321/geolbalc.51.1.15.
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Zeolite and Portland cement have been used to stabilize a loess soil from the region of Kozloduy (North Bulgaria). This paper examines the microstructural behavior of cement–zeolite treated loess soil without compaction at water content higher than optimum. Scanning electron microscopy and semi-quantitative energy dispersive spectroscopy analyses on stabilized loess were carried out after various curing periods. The identification of the formation of cementitious products in treated loess soil was conducted by SEM–EDS spectral analysis. Based on the study of the microstructural development, it was found that the modified loess microstructure undergoes significant modifications during the observed period.
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Yi, Yaolin, Martin Liska, Cise Unluer i Abir Al-Tabbaa. "Carbonating magnesia for soil stabilization". Canadian Geotechnical Journal 50, nr 8 (sierpień 2013): 899–905. http://dx.doi.org/10.1139/cgj-2012-0364.
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This paper investigates the potential for carbonating reactive magnesia (MgO) to serve as a more sustainable soil stabilization method by providing rapid and significant strength development of the stabilized soil through absorbing substantial quantities of CO2. Gaseous CO2 was forced through laboratory-prepared reactive MgO-treated soil samples in a triaxial cell set-up, and their resulting mechanical and microstructural properties were investigated using unconfined compressive strength, X-ray diffraction, and scanning electron microscopy. The results showed that adequately carbonated MgO-treated soils could, in a few hours, reach a similar strength range to corresponding 28 day Portland cement (PC)-stabilized soils. Hydrated magnesium carbonates, namely nesquehonite and hydromagnesite–dypingite, were the main products of the carbonated MgO in the soil, and were responsible for the significant strength development.
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Yin, Chenglong, Wei Zhang, Xunli Jiang i Zhiyi Huang. "Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer". Materials 11, nr 10 (10.10.2018): 1933. http://dx.doi.org/10.3390/ma11101933.
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Initial water content significantly affects the efficiency of soil stabilization. In this study, the effects of initial water content on the compressibility, strength, microstructure, and composition of a lean clay soil stabilized by compound calcium-based stabilizer were investigated by static compaction test, unconfined compression test, optical microscope observations, environment scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results indicate that as the initial water content increases in the range studied, both the compaction energy and the maximum compaction force decrease linearly and there are less soil aggregates or agglomerations, and a smaller proportion of large pores in the compacted mixture structure. In addition, for specimens cured with or without external water supply and under different compaction degrees, the variation law of the unconfined compressive strength with initial water content is different and the highest strength value is obtained at various initial water contents. With the increase of initial water content, the percentage of the oxygen element tends to increase in the reaction products of the calcium-based stabilizer, whereas the primary mineral composition of the soil-stabilizer mixture did not change notably.
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Ling, Felix N. L., Khairul Anuar Kassim i Ahmad Tarmizi Abdul Karim. "Reaction Products of Lime Zeolite Stabilized Kaolin Humic Acid". Applied Mechanics and Materials 372 (sierpień 2013): 88–96. http://dx.doi.org/10.4028/www.scientific.net/amm.372.88.
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Lime, a traditional calcium based stabilizer, had been widely used in chemical stabilization to improve the strength of soil. Past researches had shown that the major reaction product of lime and soil such as Calcium Silicate Hydrate (CSH) was formed abundantly under the observation of microscopic studies. However, sometimes it will be quite difficult to confirm the existence of CSH phase if solely based on its needle like structures, especially when other rod like structures will also exist. Practically, the recognition of the CSH phase by using XRD spectrum through matching with published data had speed up the process of identification. If the method is viable, then theoretically, the molecular weight ratio of silica and calcium, S/C of CSH gel is specific and can be determined based on its possible chemical compound. Hence, this study was carried out in an attempt to examine the possibility use of its S/C ratio as a quick method to confirm the existence of CSH gel. Two types of artificial organic soils were formed by admixing kaolin (inorganic matter) and humic acid (organic matter) with the ratio of 7:3 and 5:5. Four types of admixtures with different percentages ratio of lime and zeolite (a kind of pozzolan) were used to stabilize the soils. The specimens were cured at elevated temperature of 50°c in order to accelerate the development of reaction products. Field Emission Scanning Electron Microscope with attached Energy Dispersive Analyzer (FESEM-EDX) was utilized to observe and determine the existence of reaction products and its bulk chemical composition. The S/C ratio of needle like structures were determined and it is found that the S/C ratio fluctuates and varies significantly from one specimen to another. It is believed that due to the limitations of the experimental setup, the EDX analysis can only serve as semi-quantitative and act as a reference guide on the existence of element. Despite of its limitations, the EDX analysis is useful in distinguish the CSH from other structure which is physically un-identical.
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Manzanal, Diego, Sandra Orlandi, Mariano Fernandez, Cecilia Laskowski, Juan Cruz Barría, Mauro Codevila i Teresa Piqué. "Soil-water retention of highly expansive clay stabilized with a bio-polymer". MATEC Web of Conferences 337 (2021): 01006. http://dx.doi.org/10.1051/matecconf/202133701006.
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The unpredictable expansiveness of clayey soils due to the change of water content can be responsible for significant pathologies on civil infrastructure. This behaviour depends mainly on the physical and chemical characteristics of the clayey soil and the stress-suction state of the soil. Extensive research has been carried out to control the swelling potential of clayey soils with traditional inorganic additives such as lime and cement. However, the use of these stabilizers presents adverse implications in terms of cost and environmental impact. Bio-products and waste by-products are an environmentally friendly alternative for geotechnical soil stabilization. In this article, we assess the effect of lignin on the hydro-mechanical behaviour of highly expansive clay. The research focuses on the behaviour upon wetting and the soil-water retention properties of clay and lignin-treated clay with different percentages. Suction measurements were made by using the filter paper technique. Particular emphasis on the mercury intrusion porosimetry analysis of the untreated and treated CR-Clay is done. Results of CR-Clay with lignin-based stabilizer show significant reduction of swelling upon wetting for the higher percentage of addition. Increase of the aggregation is observed with the growth of lignin percentage. An analysis of the soil-water retention properties with the van-Genutchen model is presented.
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Sagidullina, Nazerke, Shynggys Abdialim, Jong Kim, Alfrendo Satyanaga i Sung-Woo Moon. "Influence of Freeze–Thaw Cycles on Physical and Mechanical Properties of Cement-Treated Silty Sand". Sustainability 14, nr 12 (8.06.2022): 7000. http://dx.doi.org/10.3390/su14127000.
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The problem of weak ground conditions is currently of great interest, as with the rapid development of infrastructure, researchers are trying to cope with the improvement of problematic soil properties to build structures on it. In cold regions, the problem of weak soils is further exacerbated by freeze–thaw cycling. For the improvement of soil properties, the soil stabilization method using ordinary Portland Cement (OPC) is commonly applied, but it produces a significant amount of carbon dioxide emissions. Therefore, the purpose of this research study is to present laboratory testing results for the evaluation of soil treatment using Calcium Sulfoaluminate (CSA) cement that has a lesser carbon footprint. On stabilized soil specimens cured for 3, 7, and 14 days and subjected to freeze–thaw cycles, unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) testing were performed. Samples were prepared at optimum moisture content using different cement content, 3%, 5%, and 7%. Applying the results from the UCS test, the strength loss/gain and resilient modulus of treated soil were obtained. The test results show that the strength and pulse velocity values decreased with the increase of freeze–thaw cycles. However, improvement in soil performance can be observed with the increase in cement content. Overall, the use of CSA as a stabilizer for silty sand would be useful to achieve sufficient strength of subgrade.
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Yuan, Xi Zhong, Fei Liu, Wei Cui i Cheng Cheng Liu. "Excessively Wet Subgrade Improvement with 100% Industry By-Products for Heavy Traffic Pavement – I. Solidification and Compaction Characteristics of Treated Soil". Advanced Materials Research 113-116 (czerwiec 2010): 1560–64. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.1560.
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Deformation of excessively wet subgrade is often problematic during pavements construction as well as under regular vehicular traffic loads. In order to create a sturdy and stable platform for heavy traffic pavement, a “green materials” based entirely on industry byproduct of combination fly ash (FA) with carbide lime (CL) and flue gas desulfurization gypsum (FGDG) was proposed in this study. In order to investigate the effectiveness and improvement of engineering properties, solidification test and compaction test were carried out in laboratory, and Dynamic Cone Penetrometer (DCP) was conducted at the construction site. Investigation results showed significant improvement in drying rate, workability, and mechanical behavior. The addition of FA/CL/FDG stabilizer increases the solids content by “bulking” and reduces the free moisture through hydration reactions. The addition of FA/CL/FGDG leads to an increase of approximately 18% in the maximum allowable moisture content, which would largely facilitate the compaction of the excessively wet soils. Post construction evaluation using DCP indicates the stabilized soil can be utilized under high volume traffic condition.
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Al-Kalili, Ahmed, Ahmed S. Ali i Abbas J. Al-Taie. "A Review on Expansive Soils Stabilized with Different Pozzolanic Materials". Journal of Engineering 28, nr 1 (1.01.2022): 1–18. http://dx.doi.org/10.31026/j.eng.2022.01.01.
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Soils that cause effective damages to engineer structures (such as pavement and foundation) are called problematic or difficult soils (include collapsible soil, expansive soil, etc.). These damages occur due to poor or unfavorited engineering properties, such as low shear strength, high compressibility, high volume changes, etc. In the case of expansive soil, the problem of the shrink-swell phenomenon, when the soil reacts with water, is more pronounced. To overcome such problems, soils can be treated or stabilized with many stabilization ways (mechanical, chemical, etc.). Such ways can amend the unfavorited soil properties. In this review, the pozzolanic materials have been selected to be presented and discussed as chemical stabilizers. The selected pozzolanic materials are traditional, industrial, or byproducts, ashes of agricultural wastes, and calcined-clay types. They are lime, cement, blast furnace slag, fly ash, silica fume, rice husk ash, sugarcane straw ash, egg ash, coconut husk ash, and metakaolin. In general, the stabilization of expansive soils with pozzolanic materials has an essential impact on swelling and Atterberg-limits and positively affects compaction and strength parameters. However, there is a wide range for the percentages of pozzolanic materials used as stabilizers. The content (15% to 20%) is the most ratios of the stabilizers used as an optimal percentage, and beyond this ratio, the addition of the pozzolanic materials produces an undesirable effect.
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Rudakova, L. V., E. A. Pichugin, B. E. Shenfeld i I. A. Elizarova. "Estimation of Geoecological Stability of Road Construction Material Based on Drill Cuttings". Ecology and Industry of Russia 23, nr 12 (13.12.2019): 48–53. http://dx.doi.org/10.18412/1816-0395-2019-12-48-53.
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In this article, the authors assessed the sustainability of environmental components when placing drill cuttings on the basis of the research performed. A system of restrictions has been developed for road-building mixtures based on drill cuttings and parameters have been determined, the regulation of which will ensure the production of geo-environmentally sustainable products. Compression tests of slime-sand mixtures and slimesand mixtures of Polybond soils treated with an acid stabilizer within the framework of ensuring structural stability showed that using only sand as an input component, it is impossible to obtain products that meet the requirements for deformation indicators of soils used for earthen construction road canvases. At the same time using the acid soil stabilizer, you can get products with the required strength characteristics.
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Nabizadeh Mashizi, Mahsa, Mohammad Hossein Bagheripour, Mohammad Mostafa Jafari i Ehsan Yaghoubi. "Mechanical and Microstructural Properties of a Stabilized Sand Using Geopolymer Made of Wastes and a Natural Pozzolan". Sustainability 15, nr 4 (6.02.2023): 2966. http://dx.doi.org/10.3390/su15042966.
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In this study, a combination of geopolymers including Rafsanjan Natural Pozzolan (RNP), Cement Kiln Dust (CKD), and an activator such as Calcium Carbide Residue (CCR) or NaOH was used to stabilize and improve the poorly graded sandy soil. Factors such as the activator type, activator concentration, CKD and RNP content were studied. Chemical compounds of the soil and abovementioned materials were investigated using X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) detection tests. Unconfined Compressive Strength (UCS) tests were carried out to evaluate the mechanical behavior of the specimens. The findings revealed that CKD, which is a hazardous byproduct, could be turned into an eco-friendly construction material through geopolymerization. The presence of CKD along with NaOH significantly increased the UCS of the samples compared to unstabilized specimens (control 1). Microstructural analyses using Scanning Electron Microscopy (SEM) confirmed the desirable distribution of the geopolymer gel in the stabilized soil. According to the SEM images, it was observed that the samples stabilized with CKD had a higher strength than those stabilized with CKD combined with RNP due to the formation of a greater amount of gel and a stable microstructure. The findings of this research promote sustainable ground improvement techniques using waste by-products.
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Goncharova, Margarita A., Konstantin A. Korneev i German S. Dedyaev. "Improving Construction Engineering Properties of Soils Stabilized by a Cement Binder with Techno-Genic Products". Solid State Phenomena 299 (styczeń 2020): 26–31. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.26.
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The article considers the method of stabilizing roadbed soils by introducing metallurgical waste in the structure of the composite binder. It was established during the analysis and experimental research that construction engineering properties are improved as a result of the method. The article provides the obtained results of laboratory tests. The optimum amount of ground blast furnace slag as a component to replace part of Portland cement in a soil cement mix is determined. The dependence of strength gain on the hardening time at different proportions of the composite binder is given. The efficiency of the considered method of soil hardening is estimated.
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Vignesh, N. P., K. Mahendran i N. Arunachelam. "Effects of Industrial and Agricultural Wastes on Mud Blocks Using Geopolymer". Advances in Civil Engineering 2020 (11.01.2020): 1–9. http://dx.doi.org/10.1155/2020/1054176.
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For this research, the red soil sample was drawn, and a steady percentage of the geopolymer was used along with distinct proportions of stabilizers such as fly ash, groundnut shell ash, bagasse ash, and GGBFS. Geopolymer was used in the manufacture of stabilized mud blocks as a binding agent. The geopolymer solution’s effects on mud block strength have been researched. The effects of industrial by-products and waste such as fly ash, groundnut shell ash, bagasse ash, and GGBFS were also explored with the geopolymer to stabilize the mud blocks.
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Mirzababaei, Mehdi, Jafar Karimiazar, Ebrahim Sharifi Teshnizi, Reza Arjmandzadeh i Sayed Hessam Bahmani. "Effect of Nano-Additives on the Strength and Durability Characteristics of Marl". Minerals 11, nr 10 (12.10.2021): 1119. http://dx.doi.org/10.3390/min11101119.
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Low bearing capacity soils may pose serious construction concerns such as reduced bearing capacity and excessive hydro-associated volume changes. Proper soil remediation techniques must be planned and implemented before commencing any construction on low bearing capacity soils. Environmentally friendly soil stabilizers are gradually replacing traditional soil stabilizers with high carbon dioxide emissions such as lime and cement. This study investigated the use of an alternative pozzolanic mix of nano-additives (i.e., nano-silica and nano-alumina) and cement to reduce the usage of cement for achieving competent soil stabilization outcomes. A series of unconfined compressive strength (UCS), direct shear, and durability tests were conducted on marl specimens cured for 1, 7, and 28 days stabilized with nano-additives (0.1~1.5%), 3% cement, and combined 3% cement and nano-additives. The UCS and shear strength of stabilized marl increased with nano-additives up to a threshold nano-additive content of 1% which was further intensified with curing time. Nano-additive treated cemented marl specimens showed long durability under the water, while the cemented marl decomposed early. The microfabric inspection of stabilized marl specimens showed significant growth of calcium silicate hydrate (CSH) products within the micro fabric of nano-silica treated marl with reduced pore-spaces within aggregated particles. The results confirmed that nano-additives can replace cement partially to achieve multi-fold improvement in the strength characteristics of the marl.
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Tran, Thien Quoc, Young-sang Kim, Gyeong-o. Kang, Ba Huu Dinh i Tan Manh Do. "Feasibility of Reusing Marine Dredged Clay Stabilized by a Combination of By-Products in Coastal Road Construction". Transportation Research Record: Journal of the Transportation Research Board 2673, nr 12 (2.08.2019): 519–28. http://dx.doi.org/10.1177/0361198119868196.
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Road construction work on poor subgrade in coastal, port, and reclamation sites is a traditional challenge for geotechnical engineers because of the typically very weak clayey soil in these domains. This research investigates the effects of adding a new green binder (Fa-RmLG), in different proportions and initial water contents, on the engineering properties of marine dredged clay (MDC) collected from Yeosu port, South Korea. The new green binder used is a combination of fly ash (Fa), phosphogypsum (G), lime (L), and red mud (Rm). In this study, five binder mixtures using different proportions of Fa, G, L, and Rm were blended into MDC with different water contents varying in a range of 1.2 to 2.0 times the liquid limit (LL) value. Tests of unconfined compressive strength, California bearing ratio, swelling, and shrinkage were performed on the stabilized MDC mixtures. As a result, large increases in the strength and bearing capacity as well as significant reductions of the swelling and shrinkage values of the stabilized MDC mixtures were recorded compared with unstabilized MDC. Scanning electric microscope and X-ray diffraction analyses were performed to observe the formation and presence of gels inside the stabilized MDC mixtures. Regarding environmental impact, the pH of the stabilized MDC mixtures did not increase above the corrosive limit (pH = 12.5) by the measured pH value. These results indicate that the new green binder can be used as an effective stabilizer for the stabilization of MDC in coastal road construction.
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Santoni, Rosa L., Jeb S. Tingle i Miguel Nieves. "Accelerated Strength Improvement of Silty Sand with Nontraditional Additives". Transportation Research Record: Journal of the Transportation Research Board 1936, nr 1 (styczeń 2005): 34–42. http://dx.doi.org/10.1177/0361198105193600105.
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A laboratory experiment was conducted to evaluate the effect of two products used to accelerate strength improvement of a silty sand (SM) material stabilized with nontraditional stabilizers. SM soil samples were mixed with selected products and tested under both “wet” and dry conditions after 1- and 7-day cures. Nine nontraditional stabilizers, including lignosulfonates, polymers, silicates, and tree resins, were evaluated in this experiment. Two accelerator products, an acrylic polymer and Type I portland cement, were evaluated. Samples were also stabilized with either an asphalt emulsion or cement to provide a comparison for traditional stabilizers under the same conditions. The average unconfined compressive strength (UCS) of three replicates of each mixture was compared with the results of the remaining mixtures, the traditional stabilization results, and a series of untreated control samples. The results indicate increased UCS of samples stabilized with Silicate 1 and Polymer 3 compared with both the untreated control series and the traditional stabilization alternatives. Lignosulfonate 1; Polymers 1, 2, 4, 5, and 6; and Tree Resin 1 did not demonstrate significant increased strength over the control series for the conditions of this experiment. The UCS following the 7-day cure provided the maximum UCS of the samples evaluated in both wet and dry conditions. One accelerator, cement, in combination with a nontraditional stabilizer did show significant improvement in early strength gain when compared to the control series.
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Li, Qiang, Jie Chen, Qian Shi i Shihao Zhao. "Macroscopic and Microscopic Mechanisms of Cement-Stabilized Soft Clay Mixed with Seawater by Adding Ultrafine Silica Fume". Advances in Materials Science and Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/810652.
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The strength of the cement-stabilized soil can be improved by the use of seawater. Compressive strength test results show that the strength of cement-stabilized soil mixed with seawater is 50% greater than that mixed with freshwater at the 90th day. However, the application is limited because the expansion of the cement-stabilized soil mixed with seawater increases significantly. A kind of ultrafine silica fume was added into the cement-stabilized soil to inhibit swelling of the cement-stabilized soil with seawater. The expansion of cement-stabilized soil mixed with seawater by adding ultrafine silica fume is close to that of cement-stabilized soil mixed with freshwater. With the addition of ultrafine silica fume, the unconfined compressive strength increases by close to 6.5% compared with seawater alone at the 90th day. The mechanisms of adding ultrafine silica fume into the cement-stabilized soil mixed with seawater are revealed by several physical and chemical characterization parameters, such as specific gravity, unbound water content, surface morphology seen with SEM, and crystal products by X-ray diffraction tests. The results show that the crystal growth is an important factor, affecting the strength and expansion of cement-stabilized soil mixed with seawater.
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Ling, Felix Ngee Leh, Khairul Anuar Kassim, Ahmad Tarmizi Abdul Karim i Tze Wei Chan. "Stabilization of Artificial Organic Soil at Room Temperature Using Blended Lime Zeolite". Advanced Materials Research 723 (sierpień 2013): 985–92. http://dx.doi.org/10.4028/www.scientific.net/amr.723.985.
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Organic content in soil is believed to inhibit formation of reaction products in lime stabilization which resulted in low gain of strength when dealing with organic soils. Zeolite, a kind of pozzolan with high CEC capacity is proposed to be use in this study in order to improve lime stabilization of organic soil. The effectiveness of blended lime zeolite in stabilization of organic soils was investigated by using two types of artificial organic soils with predetermined organic contents. Artificial organic soils were formed by mixing inorganic soil (commercial kaolin) with organic matter (commercial humic acid) at specific ratio. Initial consumption of lime for organic soils was determined in order to determine the minimum percentage of stabilizer required for each soil. Potential influencing factors that might affect the strength such as organic contents, contents of stabilizer, and curing periods were studied. The findings of the study showed that high organic contents and low lime contents resulted in lower gain of strength. However, it is found that slight replacement of lime with zeolite works well with low organic soil at long curing period which resulted in highest strength among all the mixes. Overall, longer curing periods will increase the strength of the soil in the order of 56 days > 28 days > 7 days. Nevertheless, the percentage of strength increment over curing periods is linear with the lime contents, which proved that lime is required for pozzolanic reaction.
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Wang, Li Feng. "Experimental Researches on Microstructure of Nanometer Silicon and Cement-Stabilized Soils". Applied Mechanics and Materials 94-96 (wrzesień 2011): 358–64. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.358.
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Unconfined compressive strength of various mixing proportions and ages of nanometer silicon and cement-stabilized soils（NCSS） are tested ,and the rules of compressive strength are got. Hydration products and microstructures of NCSS are discussed by means of XRD and SEM technology, and microstructural mechanisms of NCSS are analyzed. Results show that nanometer silicon powder added to cement-stabilized soil(CSS) can sharply improve the compressive strength of CSS. More Calcium silicate hydrates(C-S-H) and other hydration products can be produced in the process of secondary reaction of cement and water added nanometer silicon powder. X ray diffraction tests indicate the kinds and quantities of C-S-H increase with nanometer silicon contents. Strengths of NCSS are bettered by increasing jointed strength changed from edge-edge, edge-face connectios to cementation connections affected by increasing hydration products. Large pores of NCSS can be greatly decreased by adding nanometer silicon powder, and hydration products filling in the pores make NCSS more dense materials.
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Zhou, Mingkai, Xinyue Liu, Xiao Chen i Peng Gao. "Study on Strength, Water Stability, Shrinkage, and Microstructure of CFB Slag Modified Cement Stabilized Clay". Materials 14, nr 23 (5.12.2021): 7460. http://dx.doi.org/10.3390/ma14237460.
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Circulating fluidized bed slag (CFBS) is an industrial waste produced by coal combustion in power plants. To explore the application of CFB slag in cement-stabilized bases, this paper studies the influence of different dosage of CFBS on the mechanics, water stability, and shrinkage of cement-stabilized soil using laboratory experiments. The hydration activity and interface morphology of CFBS in cement-stabilized clay were observed using XRD and SEM. The improvement mechanism of CFBS on the performance of cement-stabilized clay was revealed. The results indicated that, compared with cement-stabilized clay, cement–CFBS-stabilized clay exhibited better mechanical and water stability, and significantly inhibited the shrinkage deformation of cement-stabilized clay. When the addition of CFBS was 70%, cement–CFBS-stabilized clay had the best mechanics and durability. Microscopic tests show that CFBS contains more active silicon aluminum oxide, which is easily dissolved and the hydration of which produces more gel products, so the mixture structure is denser, the strength is improved, and water does not easily evaporate; it has the characteristics of micro expansion which compensates for dry shrinkage deformation.
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Mohamad, Habib Musa, Mohd Suharmin James, Siti Nor Farhana Zakaria, Adriana Erica Amaludin, Ngui Min Fui Tom i Adnan Zainorabidin. "Effect of Eco-Processed Pozzolan (EPP) Mixed with Calcium Oxide to Dry Density and Physicochemical of Peat Soil". Civil Engineering Journal 9, nr 7 (1.07.2023): 1697–708. http://dx.doi.org/10.28991/cej-2023-09-07-011.
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Peat is a problematic soil, and it is a common problem faced by engineers in construction. The characteristics that have been noted before are high moisture content, poor shear strength, great compressibility, and long-term settlement. For this research study, it focuses on stabilizing peat soil using EPP and CaO. There are three main tests that were conducted in this research study: index properties testing, compaction testing, and For Index Properties testing, five (5) experiments were conducted to study the index properties of disturbed peat soil, which are moisture content, fiber content, liquid limit, organic content, pH, and specific gravity. Next, for the Compaction Test, using a 4.5 kg rammer, define the optimum mixture of stabilizer that is mixed with different volumes of 5%, 10%, 15%, and 20% of stabilizer. In this study, the expected result is to inspire an in-depth study of the use of EPP material and chemical CaO as peat soil stabilizers for better utilization of problematic soil. The main finding was that the mixture with the exact amount of moisture, EPP, and CaO helped stabilize the soil and cure peat soil. Thus, this study confirms the idea of treating peat with EPP and CaO, enhancing the properties of peat soil, and sustaining the settlement over loading for a period of time accordingly. 20% mix of EPP and CaO produces the highest dry density, showing that dry density increases linearly with the amount of mixture to stabilize peat. The crystallization process between peat and EPP was pronouncedly observed where smaller particles identified as EPP filled the gaps in between the pores identified from SEM. The silicon (Si content developed from each spectrum ranged from 14.4% to 17.7%. The EDX results show significant results where mineral crystallization occurred in the coagulation process. Doi: 10.28991/CEJ-2023-09-07-011 Full Text: PDF
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Raja, Ramiz, Supriya Pal i Arindam Karmakar. "IN-SITU REMEDIATION OF HEAVY METAL CONTAMINATED SITES THROUGH MECHANICAL STABILIZATION USING INDUSTRIAL WASTE PRODUCTS". Journal of Environmental Engineering and Landscape Management 30, nr 2 (8.06.2022): 301–7. http://dx.doi.org/10.3846/jeelm.2022.17077.
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The present study aimed to assess the stabilization performance of fly ash, blast furnace slag and quick lime for heavy metals in contaminated soil at a landfill site at Kolkata, West Bengal, India. The physical properties and strength parameters of the contaminated soil substantially increased after additives application. Moreover, the heavy metal concentrations in the leachate of the polluted soil were found almost nil after optimum blending of the additives mechanically with the soil and post-curing for 7 days. The numerical modeling studies were also carried out using PLAXISTM 3D software to ascertain the improvement of safety factor and deformation caused at the foundation level of an embankment constructed on such stabilized soil. The vertical displacement of the embankment founded on stabilized soil reduced from 194.3 to 136.3 mm and the safety factor of the embankment slope (1 V:1.5 H) increased from 2.5 to 3.2 under drained condition.
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Yaseen, Yaseen, i Jawdat Abbas. "An Experimental Study on Swelling Properties of Expansive Soil Treated with Iron Furnace Slag". Tikrit Journal of Engineering Sciences 27, nr 3 (15.06.2020): 61–66. http://dx.doi.org/10.25130/tjes.27.3.07.
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Using industrial waste materials in the treatment of problematic soils is an environmentally friendly and cost-effective technique. It helps in decreasing disposal issues induced by various industrial wastes. Also, it is crucial to understand the behaviour of these waste products before use. This paper presents experimental research in the treatment of expansive soil by the utilization of iron furnace slag. Laboratory program was performed to examine the effect of iron furnace slag on enhancing the engineering properties of expansive soil. Several tests included liquid limits, plastic limits, free swell percentage, swelling pressure, and unconfined compressive strength were conducted on untreated and treated soils. The efficiency of adding 0, 2, 4, and 6 percentages of iron slag to the soil was investigated. The results of the natural and iron slag stabilized soils showed that iron slag has a notable effect on strength parameters and considerable improvement in plasticity and swelling properties. The addition of iron slag to the soil increased the unconfined compressive strength while reduced the swelling potential of soil. It is concluded that the utilization of iron slag to improve the properties of expansive soil is successful and useful
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Montanarella, Luca, Daniel Jon Pennock, Neil McKenzie, Mohamed Badraoui, Victor Chude, Isaurinda Baptista, Tekalign Mamo i in. "World's soils are under threat". SOIL 2, nr 1 (29.02.2016): 79–82. http://dx.doi.org/10.5194/soil-2-79-2016.
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Abstract. The Intergovernmental Technical Panel on Soils has completed the first State of the World's Soil Resources Report. Globally soil erosion was identified as the gravest threat, leading to deteriorating water quality in developed regions and to lowering of crop yields in many developing regions. We need to increase nitrogen and phosphorus fertilizer use in infertile tropical and semi-tropical soils – the regions where the most food insecurity among us are found – while reducing global use of these products overall. Stores of soil organic carbon are critical in the global carbon balance, and national governments must set specific targets to stabilize or ideally increase soil organic carbon stores. Finally the quality of soil information available for policy formulation must be improved – the regional assessments in the State of the World's Soil Resources Report frequently base their evaluations on studies from the 1990s based on observations made in the 1980s or earlier.
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Hansen, N. E., D. M. Vietor, C. L. Munster, R. H. White i T. L. Provin. "Runoff and Nutrient Losses from Constructed Soils Amended with Compost". Applied and Environmental Soil Science 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/542873.
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Composted organic materials used to stabilize roadside embankments in Texas promote rapid revegetation of soils disturbed by construction activities. Yet, adding compost to soil may increase total and soluble plant nutrients available for loss in runoff water. Composted municipal biosolids and dairy manure products were applied to soils in Texas according to prescribed Texas Department of Transportation specifications for stabilizing roadside soils. The specifications included a method for incorporating compost into soils prior to seeding or applying a compost and woodchip mix over a disturbed soil and then seeding. Applying compost and woodchips over the soil surface limited sediment losses (14 to 32 fold decrease) compared to incorporating compost into the soil. Yet, the greatest total phosphorus and nitrogen losses in runoff water occurred from soils where the compost and woodchip mix was applied. The greatest losses of soluble phosphorus also occurred when the compost and woodchip mix was applied. In contrast, nitrate-nitrogen losses in runoff were similar when compost was incorporated in the soil or applied in the woodchip mix. Compost source affected the nutrient losses in runoff. While the composted municipal biosolids added greater nutrient loads to the soil, less nutrient loss in runoff occurred.
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Montanarella, L., D. J. Pennock, N. J. McKenzie, M. Badraoui, V. Chude, I. Baptista, T. Mamo i in. "World's soils are under threat". SOIL Discussions 2, nr 2 (9.12.2015): 1263–72. http://dx.doi.org/10.5194/soild-2-1263-2015.
Pełny tekst źródłaStreszczenie:
Abstract. The Intergovernmental Technical Panel on Soils has completed the first State of the World's Soil Resources report. Globally soil erosion was identified as the gravest threat, leading to deteriorating water quality in developed regions and to lowering of crop yields in many developing regions. We need to increase nitrogen and phosphorus fertilizer use in infertile tropical and semi-tropical soils – the regions where the most food insecure among us are found – while reducing global use of these products overall. Stores of soil organic carbon are critical in the global carbon balance, and national governments must set specific targets to stabilize or ideally increase soil organic carbon stores. Finally the quality of soil information available for policy formulation must be improved – the regional assessments in the SWSR report frequently base their evaluations on studies from the 1990s based on observations made in the 1980s or earlier.
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Chao, Yan, Liu Songyu i Deng Yongfeng. "Experimental Research for the Application of Mining Waste in the Trench Cutting Remixing Deep Wall Method". Advances in Materials Science and Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/202848.
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This paper focuses on the use of fly ash (FA) or ground granulated blast slag (GGBS) and reactive lime blends for cement-stabilized Nanjing clay, comparing them with Portland cement (PC) for enhanced technical performance. A range of tests were conducted to investigate the properties of stabilized soils, including macrostrength (UCS), permeability, and microstructure analyses by scanning electron microscopy (SEM). The influence of PC : (FA + lime) ratio, PC : (GGBS + lime) ratio and curing time was addressed. The UCS and permeability results revealed that PC-FA-lime was more efficient than PC-GGBS-lime as a binder for soil stabilization, with an optimum proportion of PC : (FA + lime) = 3 : 7 at 25% binder content, varying with curing time. The microstructure analysis reveals that fly ash mainly changes the pore volume distribution, which ranges between 0.01 μm and 1 μm, and produces more CSH/CASH bonding and fissures due to the secondary hydration and pozzolanic reactions. Based on the favourable results obtained, it can be concluded that the soft soils can be successfully stabilized by the combined action of cement, fly ash, and lime. Since fly ash is much cheaper than cement, the addition of fly ash and lime in cement-soil mix may particularly become attractive and can result in cost reduction of construction.
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Fér, Miroslav, Radka Kodešová, Aleš Klement i Antonín Nikodem. "The impact of treated wastewater and biosolids from the municipal wastewater treatment plant on water and carbon dioxide effluxes from soils". Journal of Hydrology and Hydromechanics 70, nr 3 (23.08.2022): 276–83. http://dx.doi.org/10.2478/johh-2022-0022.
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Abstract The goal of this study was to evaluate the effect of products from a municipal wastewater treatment plant on the H2O and CO2 effluxes from two soils. The net H2O and CO2 effluxes were measured at the surface of nine beds with two different soils (Cambisol and Arenosol) and two crops (maize or vegetables). Soils in some beds were amended with stabilized sewage sludge (bed with Cambisol and maize) or composted sewage sludge (two beds with Cambisol and both crops) or were irrigated with treated wastewater (two beds with Cambisol and both crops, and one bed with Arenosol and vegetable). Remaining beds were irrigated with tap water (two beds with Cambisol and both crops, and one bed with Arenosol and vegetable). While stabilized and composted sewage sludge positively affected the CO2 emission, the effect of treated wastewater was not confirmed. Different treatments had negligible effect on the water efflux, which was mainly affected by the plant canopy that influence the temperature of the soil surface. Statistical analyses showed that trends of the CO2 efflux with respect to various scenarios measured on different days changed during the season. No significant correlations were found between the average H2O and CO2 effluxes and measured soil properties.
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Malkanthi, S. N. "An Innovative Approach to Produce Soil-Based Building Products". Bolgoda Plains 01, nr 01 (październik 2021): 58–59. http://dx.doi.org/10.31705/bprm.2021.17.
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Soil has been used as a building material in different forms, such as mud, adobe, rammed earth, and bricks. Compressed Stabilized Earth Block (CSEB), a form of soil blocks with different additives including cement, fly ash, and lime, is a sustainable building material with many advantages compared to other conventional building materials. The usual practice of past researchers in producing CSEB was to add different materials like sand to the soil to control its clay and silt (finer) content. A high level of finer content is not desirable when it comes to the strength and durability of CSEB. This study proposes to reduce/ extract the finer content in the soil by washing it using a conventional concrete mixing machine.
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Gies, Hannah, Frank Hagedorn, Maarten Lupker, Daniel Montluçon, Negar Haghipour, Tessa Sophia van der Voort i Timothy Ian Eglinton. "Millennial-age glycerol dialkyl glycerol tetraethers (GDGTs) in forested mineral soils: <sup>14</sup>C-based evidence for stabilization of microbial necromass". Biogeosciences 18, nr 1 (12.01.2021): 189–205. http://dx.doi.org/10.5194/bg-18-189-2021.
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Abstract. Understanding controls on the persistence of soil organic matter (SOM) is essential to constrain its role in the carbon cycle and inform climate–carbon cycle model predictions. Emerging concepts regarding the formation and turnover of SOM imply that it is mainly comprised of mineral-stabilized microbial products and residues; however, direct evidence in support of this concept remains limited. Here, we introduce and test a method for the isolation of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) – diagnostic membrane lipids of archaea and bacteria, respectively – for subsequent natural abundance radiocarbon analysis. The method is applied to depth profiles from two Swiss pre-Alpine forested soils. We find that the Δ14C values of these microbial markers markedly decrease with increasing soil depth, indicating turnover times of millennia in mineral subsoils. The contrasting metabolisms of the GDGT-producing microorganisms indicates it is unlikely that the low Δ14C values of these membrane lipids reflect heterotrophic acquisition of 14C-depleted carbon. We therefore attribute the 14C-depleted signatures of GDGTs to their physical protection through association with mineral surfaces. These findings thus provide strong evidence for the presence of stabilized microbial necromass in forested mineral soils.
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Shi, Jian, Shengnian Wang, Wenzhe Cao, Jun Su i Xingjin Zhang. "Mechanical Properties and Strengthening Mechanism of Dredged Silty Clay Stabilized by Cement and Steel Slag". Materials 15, nr 11 (27.05.2022): 3823. http://dx.doi.org/10.3390/ma15113823.
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The high moisture content and low strength of dredged soft soils result in significant difficulties in directly reutilizing them in engineering. Improving their mechanical properties effectively and achieving re-utilization with the maximum benefit in engineering is the key to disposing of dredged soils with high moisture content. This study investigated the influences of cement and steel slag ratio, moisture content, the maximum particle size of steel slag, and curing age on the compressive strength of dredged silty clay in a plastic flow state. The performance improvement of dredged silty clay stabilized with cement and steel slag was discussed by comparing to related previous studies. The strengthening mechanism of dredged soils stabilized with cement and steel slag was explored by microstructural observation. The results show that when the ratio of cement to steel slag was 9:6; namely, using steel slag to replace 40% of cement, the strength properties of dredged silty clay stabilized by cement and steel slag could ensure the minimum requirements of the project greater then 100 kPa, and their economics could achieve the best results. The finer the particle size of steel slag was, the better the stabilization effect was. The compressive strength of dredged silty clay stabilized by cement and steel slag with particle sizes of less than 0.075 mm was 1.06 times, 1.10 times, and 1.16 times that of 0.25 mm, 1 mm, and 2 mm and increased linearly over curing ages earlier than 28 days. The compressive strength of dredged silty clay stabilized by cement and steel slag cured for 28 days was 2.44 times, 1.59 times, and 1.36 times that of 3, 7, and 14 days, respectively. The evolution of microstructural characteristics showed that the internal pore sizes of dredged soil decreased the structural compactness increased significantly due to the formation of more calcium silicate hydrate and other agglomerated flocculent gel materials from the further reaction between steel slag and cement hydration products. The results of this study can provide technological parameters for the re-utilization of dredged soil stabilized with cement and steel slag.
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Abdila, Syafiadi Rizki, Mohd Mustafa Al Bakri Abdullah, Romisuhani Ahmad, Dumitru Doru Burduhos Nergis, Shayfull Zamree Abd Rahim, Mohd Firdaus Omar, Andrei Victor Sandu, Petrica Vizureanu i Syafwandi. "Potential of Soil Stabilization Using Ground Granulated Blast Furnace Slag (GGBFS) and Fly Ash via Geopolymerization Method: A Review". Materials 15, nr 1 (5.01.2022): 375. http://dx.doi.org/10.3390/ma15010375.
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Geopolymers, or also known as alkali-activated binders, have recently emerged as a viable alternative to conventional binders (cement) for soil stabilization. Geopolymers employ alkaline activation of industrial waste to create cementitious products inside treated soils, increasing the clayey soils’ mechanical and physical qualities. This paper aims to review the utilization of fly ash and ground granulated blast furnace slag (GGBFS)-based geopolymers for soil stabilization by enhancing strength. Previous research only used one type of precursor: fly ash or GGBFS, but the strength value obtained did not meet the ASTM D 4609 (<0.8 Mpa) standard required for soil-stabilizing criteria of road construction applications. This current research focused on the combination of two types of precursors, which are fly ash and GGBFS. The findings of an unconfined compressive strength (UCS) test on stabilized soil samples were discussed. Finally, the paper concludes that GGBFS and fly-ash-based geo-polymers for soil stabilization techniques can be successfully used as a binder for soil stabilization. However, additional research is required to meet the requirement of ASTM D 4609 standard in road construction applications, particularly in subgrade layers.
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Ji, Enyue, Fei Xu, Hua Wei, Wenxun Qian, Yang He i Pengfei Zhu. "An Investigation on Mineral Dissolution and Precipitation in Cement-Stabilized Soils: Thermodynamic Modeling and Experimental Analysis". Applied Sciences 12, nr 14 (6.07.2022): 6843. http://dx.doi.org/10.3390/app12146843.
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Thermodynamic modeling helps to reveal insights into the basic chemical kinetics of dissolution and precipitation in cementitious materials, but relevant applications to cement-stabilized soils have seldom been reported. Based on the thermodynamic database of Cemdata18 and the pore solution composition of cement-stabilized soils, this study formulated a specialized thermodynamic model, using essential thermodynamic constants for soil minerals that were calculated to ensure the model’s accuracy. Two commercial admixtures of alkaline activator and polynaphthalene sulfonate were selected for the different modification mechanisms and plain and modified cement-stabilized soils were prepared. Compressive strength was tested to determine the specimens for pore solution analysis and the influences of the admixture type and dose on dissolution and precipitation were investigated by modeling the ionic activity products and saturation indexes. An X-ray diffraction (XRD) analysis was performed to verify and complement the thermodynamic results. The major research findings were that (1) thermodynamic modeling can be reliably applied to cement-stabilized soils by providing the essential thermodynamic data and an appropriate product model, (2) the pozzolanic reaction is accelerated by increasing the OH− concentration in the pore solution, while the cement hydration is highly dependent on the dissolution of Ca(OH)2 and the relevant complexes and (3) the dissolution equilibrium of Ca(OH)2 is directly affected by the alkaline activator dissolution and is indirectly affected by the polynaphthalene sulfonate adsorption of the reactants.
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Santos de Oliveira, Leandro, Normando Perazzo Barbosa, Fabiana Silva Santos i Carlos Maviael de Carvalho. "Stabilization of Raw Earth through Alkaline Activation". Key Engineering Materials 600 (marzec 2014): 215–24. http://dx.doi.org/10.4028/www.scientific.net/kem.600.215.
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Stabilization is important in earthen construction in order to improve mechanical strength, volumetric stability, workability and even ductility. Currently, the products used to stabilize the earth are lime, Portland cement and bitumen emulsions. Due to the environmental problems that the mankind faces nowadays, the use of earthen construction is increasing. Adobe is the most traditional type of block used in masonry. To improve strength against water, a new way to stabilize this kind of unburned earth block is proposed by the alkaline activation of earth. This paper presents the first results about the experimentation made in the stabilization of soil with alkali activator. Two cure temperatures were tested: room temperature and oven at 50°C. The amounts of stabilizer used were 3% and 6% activator by mass of earth. Results show that it is possible for adobe blocks to be resistant to water action using the alkaline activation.
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Du, Yan-Jun, Ning-Jun Jiang, Song-Yu Liu, Fei Jin, Devendra Narain Singh i Anand J. Puppala. "Engineering properties and microstructural characteristics of cement-stabilized zinc-contaminated kaolin". Canadian Geotechnical Journal 51, nr 3 (marzec 2014): 289–302. http://dx.doi.org/10.1139/cgj-2013-0177.
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This paper presents details of a study that deals with determination of engineering properties, identification of phases of major hydration products, and microstructural characteristics of a zinc-contaminated (referred to as Zn-contaminated in this paper) kaolin clay when it is stabilized by a cement additive. Investigations were carried out with respect to the effect of the level of zinc (Zn) concentration on the overall soil properties including Atterberg limits, water content, pH, stress–strain characteristics, unconfined compressive strength, and secant modulus. In addition, X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry studies were conducted to understand the mechanisms controlling the changes in engineering properties of the stabilized kaolin clay. The study reveals that the level of Zn concentration has a considerable influence on the engineering properties, phases of hydration products formed, and microstructural characteristics of the stabilized kaolin clay. These changes are attributed to the retardant effect of Zn on the hydration and pozzolanic reactions, which in turn alters the phases of hydration products and cementation structure – bonding of the soils. Theoretical simulation of the pore-size distribution curves demonstrates that the cement-stabilized kaolin exhibits bimodal type when the Zn concentration is less than 2%, whereas it displays unimodal type when the Zn concentration is 2%. With an increase in the Zn concentration, the characteristics of the interaggregate pores in terms of volume and mean diameter change considerably, whereas those of intra-aggregate pores remain nearly unchanged.