Journal articles: 'Mechanical carbonation'

1

Wang, Jia Bin, Di Tao Niu, Rui Ma, and Ze Long Mi. "Influence the Carbonation Resistance and Mechanical Properties of Shotcrete by Accelerated Carbonation Test." Advanced Materials Research 1065-1069 (December 2014): 1985–89. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1985.

Full text

Abstract:

In order to investigate the carbonation resistance of shotcrete and the mechanical properties after carbonation, the accelerated carbonation test was carried out. The results indicate that the carbonation resistance of shotcrete is superior to that of normal concrete. With the increasing of carbonation depth, compressive strength and splitting tensile strength of shotcrete grew rapidly. The admixing of steel fiber can further improve the carbonation resistance, reduce the carbonation rate, and increase the splitting tensile strength of shotcrete greatly. Besides, based on analyzing the effects of construction technology and steel fiber of concrete for the carbonation resistance, a carbonation depth model for shotcrete was established. Key words: shotcrete; carbonation; steel fiber; mechanical properties

APA, Harvard, Vancouver, ISO, and other styles

2

Wu, Qi Sheng, Hong Xia Gu, Tao Yang, Chang Sen Zhang, Zhi An Min, and Yang Wu. "Analysis of Mechanical Performance and Microstructure of Steel Slag Processed with Accelerated Carbonation." Materials Science Forum 944 (January 2019): 1240–51. http://dx.doi.org/10.4028/www.scientific.net/msf.944.1240.

Full text

Abstract:

The accelerated carbonation with different pressure steaming conditions was used to process the steel slag, so the slag could turn into a primary cementitious product with carbonation activity. XRD, FTIR, TG, N2 absorption BET surface area analyzer and SEM were used to characterize the mineral and chemical compositions and microstructure of each sample before and after the carbonation. The results show that: the carbonation products with different morphologies are formed under different temperature conditions. The optimum temperature for the accelerated carbonation for processing the steel slag is selected to be 90 °C, which results in the compressive strength of 32.8 MPa. The BET specific surface area of the steel slag reduces after carbonation, the sample density increased after carbonation.

APA, Harvard, Vancouver, ISO, and other styles

3

Wang, Weikang, Xuanchun Wei, Xinhua Cai, Hongyang Deng, and Bokang Li. "Mechanical and Microstructural Characteristics of Calcium Sulfoaluminate Cement Exposed to Early-Age Carbonation Curing." Materials 14, no. 13 (June 24, 2021): 3515. http://dx.doi.org/10.3390/ma14133515.

Full text

Abstract:

The early-age carbonation curing technique is an effective way to improve the performance of cement-based materials and reduce their carbon footprint. This work investigates the early mechanical properties and microstructure of calcium sulfoaluminate (CSA) cement specimens under early-age carbonation curing, considering five factors: briquetting pressure, water–binder (w/b) ratio, starting point of carbonation curing, carbonation curing time, and carbonation curing pressure. The carbonization process and performance enhancement mechanism of CSA cement are analyzed by mercury intrusion porosimetry (MIP), thermogravimetry and derivative thermogravimetry (TG-DTG) analysis, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that early-age carbonation curing can accelerate the hardening speed of CSA cement paste, reduce the cumulative porosity of the cement paste, refine the pore diameter distribution, and make the pore diameter distribution more uniform, thus greatly improving the early compressive strength of the paste. The most favorable w/b ratio for the carbonization reaction of CSA cement paste is between 0.15 and 0.2; the most suitable carbonation curing starting time point is 4 h after initial hydration; the carbonation curing pressure should be between 3 and 4 bar; and the most appropriate time for carbonation curing is between 6 and 12 h.

APA, Harvard, Vancouver, ISO, and other styles

4

Babalola, O. E., Paul O. Awoyera, D. H. Le, Oladimeji B. Olalusi, and S. K. Bhagat. "Anthropogenic Carbon Aerosol Induced Carbonation in Reinforced Concrete: Deterioration Effects on Mechanical Properties." International Journal of Engineering Research in Africa 57 (November 9, 2021): 139–48. http://dx.doi.org/10.4028/www.scientific.net/jera.57.139.

Full text

Abstract:

The effects of corrosion on the reinforced concrete structure due to carbonation affect its operation life. The research work considers a major critical component causing global warming as it studies the links between reinforced concrete deterioration mechanisms and anthropogenic carbon aerosol (black carbon soot) emissions in the atmosphere. Experimental tests were carried out to study the effect of carbonation caused by the emission of black carbon soot on mechanical properties and durability of reinforced concrete. Mass concrete and reinforced concrete prepared with Ordinary Portland cement (OPC) in water/cement ratios ranging from 0.45 to 0.65 were used to produce concrete samples. Compressive strength tests, tensile strength test, and carbonation depth tests were carried out on concrete to determine its level of deterioration following the carbonation effect. The carbonation chamber was prepared with carbon soot of different concentrations to simulate different levels of black carbon soot in the atmosphere. Results showed that concrete compressive strength was not totally affected by carbonation, but there was reduction in the tensile strength of reinforcing steel. The carbonation depth was observed to progress deeper into the concrete with a longer duration of exposure to carbonation agents in the chamber. The result of this study will serve as a guide during concrete installations.

APA, Harvard, Vancouver, ISO, and other styles

5

Unluer, Cise. "Investigating the Carbonation and Mechanical Performance of Reactive MgO Cement Based Concrete Mixes." Nano Hybrids and Composites 19 (February 2018): 23–33. http://dx.doi.org/10.4028/www.scientific.net/nhc.19.23.

Full text

Abstract:

Carbonation governs the microstructure and the overall mechanical performance of mixes involving MgO cements as the main binder. Aggregate grading has a significant influence on the carbonation process due to the different particle arrangements that determine the porosity and permeability of the resulting formulations. This work investigates the effect of aggregate particle size distribution on the carbonation of blocks containing reactive MgO. Samples containing four different aggregate profiles were subjected to accelerated carbonation at 20% CO2 concentration for up to 28 days. While the influence of gap grading on strength development was not very pronounced, mixes with the lowest initial porosity indicated the greatest increase in density at the end of 28 days. This also translated into the highest strength results obtained due to the formation of hydrated magnesium carbonates, reaching 10 MPa only after 1 day of carbonation. The porosity values measured before carbonation were inversely correlated with the corresponding densities and final strengths of each mix. An inverse correlation between porosity and permeability values before carbonation led to the conclusion that the connectivity of pores rather than the total pore volume controls the carbonation reaction. Mixes with higher initial permeabilities achieved the highest strengths, proving that the extent of CO2 diffusivity is mainly dependent on pore connectivity.

APA, Harvard, Vancouver, ISO, and other styles

6

Kim, Hayeon, and Hyeongmin Son. "Utilization of Bio-Mineral Carbonation for Enhancing CO2 Sequestration and Mechanical Properties in Cementitious Materials." Buildings 12, no. 6 (May 30, 2022): 744. http://dx.doi.org/10.3390/buildings12060744.

Full text

Abstract:

Microorganisms can perform mineral carbonation in various metabolic pathways, and this process can be utilized in the field of construction materials. The present study investigated the role of bio-mediated mineral carbonation in carbon sequestration performance and mechanical properties of cementitious materials. Bacterial-mediated ureolysis and CO2 hydration metabolism were selected as the main mechanisms for the mineral carbonation, and a microorganism, generating both urease and carbonic anhydrase, was incorporated into cementitious materials in the form of a bacterial culture solution. Four paste specimens were cured in water or carbonation conditions for 28 days, and a compressive strength test and a mercury intrusion porosimetry analysis were performed to investigate the changes in mechanical properties and microstructures. The obtained results showed that the pore size of the specimens incorporating bacteria was reduced by the precipitation of CaCO3 through the mineral carbonation process, thereby improving the mechanical properties of the paste specimens, regardless of the curing conditions. In addition, in the case of the paste specimens cured in carbonation conditions, more amorphous CaCO3 was observed and a larger amount of CaCO3 in the specimens incorporating the bacteria was measured than in the specimens without bacteria. This is attributed to promotion of the inflow and diffusion of CO2 via mineral carbonation through bacterial CO2 hydration metabolism.

APA, Harvard, Vancouver, ISO, and other styles

7

Kim, Jung J., Kwang-Soo Youm, and Jiho Moon. "A Study on Conversion Fraction and Carbonation of Pozzolan Blended Concrete through 29Si MAS NMR Analysis." Applied Sciences 10, no. 19 (September 29, 2020): 6855. http://dx.doi.org/10.3390/app10196855.

Full text

Abstract:

The object of this paper is to investigate the carbonation resistance of concretes containing different pozzolanic materials. Three concrete mixtures that included fly ash, silica fume, and nanosilica were prepared, and the mixtures were designed to have similar mechanical properties to exclude the effect of mechanical properties on the carbonation. These pozzolanic materials in concretes have different silicate contents and grain size distributions. Rapid carbonation tests were conducted to investigate the durability of pozzolan blended concretes for carbonation, and the carbonation depth was measured at one, two, four, and eight weeks after 28-day water curing. 29Si NMR (nuclear magnetic resonance) experiments were performed, and the conversion fractions for each pozzolan blended concrete were extracted. The degree of carbonation was also assessed based on the Nuclear magnetic resonance (NMR) results.

APA, Harvard, Vancouver, ISO, and other styles

8

Liu, Zhiyuan, Philip Van den Heede, and Nele De Belie. "Effect of the Mechanical Load on the Carbonation of Concrete: A Review of the Underlying Mechanisms, Test Methods, and Results." Materials 14, no. 16 (August 6, 2021): 4407. http://dx.doi.org/10.3390/ma14164407.

Full text

Abstract:

As one of the major causes of concrete deterioration, the carbonation of concrete has been widely investigated over recent decades. In recent years, the effect of mechanical load on carbonation has started to attract more attention. The load-induced variations in crack pattern and pore structure have a significant influence on CO2 transport which determines the carbonation rate. With different types of load, the number, orientation, and position of the induced cracks can be different, which will lead to different carbonation patterns. In this review paper, the carbonation in cracked and stress-damaged concrete is discussed first. Then, literature about the effect of sustained load during carbonation is compared in terms of load type and load level. Finally, the advantages and disadvantages of possible test methods for investigating the effect of sustained load on carbonation are discussed with respect to loading devices, load compensation, and specimen size.

APA, Harvard, Vancouver, ISO, and other styles

9

C. M., Ikumapayi, Adeniji A. A., Obisesan A. A., Odeyemi O., and Ajayi J. A. "Effects of Carbonation on the Properties of Concrete." Scientific Review, no. 512 (December 5, 2019): 205–14. http://dx.doi.org/10.32861/sr.512.205.214.

Full text

Abstract:

Concrete is one of the reliable, durable, economical and acceptable construction materials among the building and construction stakeholders worldwide. Performance of concrete could be threatened especially reinforced concrete by some processes such as corrosion, sulfate attack among others. Corrosion of reinforcement in reinforced concrete can be induced by carbonation process. Even though carbonation initiates corrosion, it has been gathered that carbonation could still be of immense benefits to building and construction industries if its mechanism of operation is understudied. This research work has therefore investigated the effect of carbonation on some selected mechanical properties of concrete such as compressive strength, flexural strength, water absorption and weight changes. Concrete cubes and beams of M15 grade with 0.5 % water-cement ratio were prepared and subjected to accelerated carbonation. Their compressive strength, flexural strength, water absorption and weight changes were determined in accordance with the relevant standards. The outcomes show that carbonation improves all the mechanical properties investigated. The use of carbonation can be positively explored in reinforced concrete provided there is adequate nominal cover.

APA, Harvard, Vancouver, ISO, and other styles

10

Li, Zhen, Zhen He, and Xiaorun Chen. "The Performance of Carbonation-Cured Concrete." Materials 12, no. 22 (November 12, 2019): 3729. http://dx.doi.org/10.3390/ma12223729.

Full text

Abstract:

The research shows that carbonation-cured concrete has several mechanical and durability properties that are better than those of moisture-cured concrete. However, many properties of carbonation-cured concrete have not yet been studied. In this research, carbonation-cured concrete was prepared by pre-curing, carbonation curing, and then moisture curing. The compressive strength, CO2 uptake, pH value, chloride ion permeability and abrasion resistance of the carbonation-cured concrete were investigated. Results showed that the compressive strength of carbonation-cured concrete was more than 10% higher than that of moisture-cured concrete at the same age; a steel bar is stable in carbonation-cured concrete; and carbonation-cured concrete exhibited better abrasion resistance and chloride ion permeability than that of moisture-cured concrete. The optimization of pore structure and improvement in the micro-hardness are the reasons for the improved chloride ion permeability and abrasion resistance of carbonation-cured concrete.

APA, Harvard, Vancouver, ISO, and other styles

11

Arizzi, Anna, Javier Martínez Martínez, Giuseppe Cultrone, and David Benavente. "Mechanical Evolution of Lime Mortars during the Carbonation Process." Key Engineering Materials 465 (January 2011): 483–86. http://dx.doi.org/10.4028/www.scientific.net/kem.465.483.

Full text

Abstract:

Lime mortar is one of the most ancient and durable building materials. It is characterized by a slow carbonation during which Ca(OH)2 reacts with CO2 present in air and forms calcite, giving rise to a stronger and more compact material. This process takes place from the surface to the interior of the material and it is strongly affected by the reaction conditions. The aim of this study is to quantify the increase in strength and elasticity of different lime mortars according to their carbonation degree. For that, six types of mortars were elaborated, with different lime/aggregate proportions and aggregate mineralogy and grading. Mineralogical and textural studies were carried out to follow the carbonation process. Each mortar was tested in a uniaxial compression press after 15, 28, 60 days from the elaboration. In order to differentiate the mechanical behaviour of the external and internal parts of the mortars, two micro-samples (10×10×10 mm) were obtained from the first 10 mm and from the core of each prism. Results show that an increase in strength and especially in the elastic modulus is associated to the carbonation process, but it is different depending on the composition and compactness of the mortars.

APA, Harvard, Vancouver, ISO, and other styles

12

Wang, Qing Long, and Jun Chao Bao. "Effect of Silica Fume on Mechanical Properties and Carbonation Resistance of Concrete." Applied Mechanics and Materials 238 (November 2012): 161–64. http://dx.doi.org/10.4028/www.scientific.net/amm.238.161.

Full text

Abstract:

A designed experimental study has been conducted to investigate the effect of silica fume on mechanical properties and carbonation resistance of concrete, a large number of experiments have been carried out in this study. The results indicate that the addition of silica fume has improved the compression strength and elastic modulus of concrete. A considerable increase for the compression strength and elastic modulus of the concrete was observed by increasing the dosage of silica fume. Besides, the addition of silica fume can improve the carbonation resistance of the concrete composite evidently, and the carbonation resistance is becoming better and better as the silica fume content is increasing gradually.

APA, Harvard, Vancouver, ISO, and other styles

13

Wang, Xiao Yong. "Evaluation Carbonation Service Life of Mortar-Coated Concrete Considering Global Warming." Materials Science Forum 1041 (August 4, 2021): 95–100. http://dx.doi.org/10.4028/www.scientific.net/msf.1041.95.

Full text

Abstract:

Mortar finishing is frequently used to improve the carbonation service life of structural concrete. Moreover, carbonation is aggravated due to global warmings, such as the increase of CO2 concentration and temperature. This study shows a probability-based approach for evaluating the carbonation service life of coated concrete considering global warming. First, a carbonation model is proposed for assessing the carbonation depth of concrete with mortar finishing. The effect of global warming on carbonation is considered in the carbonation model. Second, a probability-based method is employed to determine the carbonation service life considering the thickness and mixtures of mortar finishing and substrate concrete. Based on the statistical analysis of calculation results, we find that for a concrete structural with 50 years’ service life, 15% service life will be reduced due to global warming.

APA, Harvard, Vancouver, ISO, and other styles

14

Zhang, Lan Fang, Liu Yang, Bin Hong Fu, and Yu Yue. "Research Progress on Carbonation Resistance of Alkali-Activated Slag Cement Concrete." Materials Science Forum 1036 (June 29, 2021): 347–57. http://dx.doi.org/10.4028/www.scientific.net/msf.1036.347.

Full text

Abstract:

The carbonation process in alkali-activated slag cement concrete is more complicated. This paper reviews the research progress of carbonation resistance of alkali-activated slag cement concrete at home and abroad and summarizes the existing research on carbonation. The focus is on the carbonation mechanism, test methods, influencing factors and the effect of carbonation on the performance of alkali-activated slag cement concrete. The problems existing in the current research on the anti-carbonation property of alkali-activated slag cement concrete and the issues for further research are proposed.

APA, Harvard, Vancouver, ISO, and other styles

15

Chen, Tian-Wen, Jin Wu, and Guo-Qing Dong. "Mechanical Properties and Uniaxial Compression Stress—Strain Relation of Recycled Coarse Aggregate Concrete after Carbonation." Materials 14, no. 9 (April 26, 2021): 2215. http://dx.doi.org/10.3390/ma14092215.

Full text

Abstract:

The application of recycled coarse aggregate (RCA) made from waste concrete to replace natural coarse aggregate (NCA) in concrete structures can essentially reduce the excessive consumption of natural resources and environmental pollution. Similar to normal concrete structures, recycled concrete structures would also suffer from the damage of carbonation, which leads to the deterioration of durability and the reduction of service life. This paper presents the experimental results of the cubic compressive strength, the static elastic modulus and the stress–strain relation of recycled coarse aggregate concrete (RAC) after carbonation. The results show that the cubic compressive strength and the static elastic modulus of carbonated RAC gradually increased with the carbonation depth. The uncarbonated and fully carbonated RAC show smaller static elastic modulus than natural aggregate concrete (NAC). As the carbonation depth increased, the peak stress increased, while the peak strain decreased and the descending part of the curves gradually became steeper. As the content of RCA became larger, the peak stress decreased, while the peak strain increased and the descending part of the curves gradually became steeper. An equation for stress–strain curves of RAC after carbonation was proposed, and it was in good agreement with the test results.

APA, Harvard, Vancouver, ISO, and other styles

16

Kim, Yoo Taek, and Jun Young Park. "Additional Aging Effect after Carbonation Process of Fly Ash Based Eco-Materials." Applied Mechanics and Materials 302 (February 2013): 61–65. http://dx.doi.org/10.4028/www.scientific.net/amm.302.61.

Full text

Abstract:

The purpose of this study is to enhance the mechanical strength of specimens containing fly ash from fluidized bed type boiler, which the recycling rate will be eventually increased. Specimens containing fly ash in a certain portion were made and aged for 3, 14, and 21 days. The carbonation process under the super critical condition was performed to enhance the mechanical property of specimens by filling the voids and cracks existing inside cement specimen with CaCO3 reactants. The additional aging effect after the supercritical carbonation process on mechanical strength of specimens was also investigated by comparing the compressive strength with and without 7 day extra aging. Carbonation under the supercritical condition and additional 7 day aging was very effective for enhancement of mechanical strength and compressive strength increased by 44%, which reached up to 88MPa.

APA, Harvard, Vancouver, ISO, and other styles

17

Xie, Xiao Ying, Hao Wei, Xiao Bao Zuo, and Dong Cui. "Effect of Carbonation on Microstructure Evolution of Alkali-Activated Slag Pastes." Key Engineering Materials 929 (August 24, 2022): 201–12. http://dx.doi.org/10.4028/p-hp6t1t.

Full text

Abstract:

In order to reveal the carbonation mechanism of alkali-activated concrete, the accelerated carbonation tests based on alkali-activated slag pastes were carried out. The evolution of microstructure and chemical composition for alkali-activated slag pastes subjected to carbonation was analyzed combining thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP) and a recently developed extended X-ray attenuation method (XRAM). The results showed that, the microstructure of alkali-activated slag pastes deteriorated gradually. Based on MIP and XRAM, the porosity of S4 (sample with a water-binder ratio of 0.4) increased by 8.24% and 11% after carbonation, and that of S6 (sample with a water-binder ratio of 0.6) increased by 7.45% and 10%, respectively. Besides, thermal analysis showed that, after carbonation, 11.45 mol / L and 19.57 mol /L CaCO3 were produced separately by S4 and S6. The main carbonation product for S6 was calcite, but for S4 vaterite and disorderly stacked calcite were also presented.

APA, Harvard, Vancouver, ISO, and other styles

18

Stavař, Tomáš, and Michal Stehlík. "Carbonation Depth vs. Physical-Mechanical Properties of Concretes with Alternative Additions of Concrete Recyclate and Silicate Admixtures." Advanced Materials Research 897 (February 2014): 290–96. http://dx.doi.org/10.4028/www.scientific.net/amr.897.290.

Full text

Abstract:

The paper focuses on exploring the correlation dependence between the physical-mechanical properties of concretes and alternatively concretes with concrete recyclate and silicate admixtures and the susceptibility of concretes to carbonation. Determining the susceptibility of concretes to carbonation by testing the permeability of their surface layer using the TORRENT, ISAT, or GWT methods is relatively lengthy and requires expensive instrumentation. The first estimate of durability or susceptibility of concretes to carbonation can be easily made on the basis of standard physical-mechanical tests. It seems that the values of volume masses and tensile splitting strengths of concretes could be a good basis for the estimate of their durability.

APA, Harvard, Vancouver, ISO, and other styles

19

Pokorný, Jaroslav, Milena Pavlíková, and Zbyšek Pavlík. "Effect of CO₂ Exposure on Mechanical Resistivity of Cement Pastes with Incorporated Ceramic Waste Powder." Materials Science Forum 824 (July 2015): 133–37. http://dx.doi.org/10.4028/www.scientific.net/msf.824.133.

Full text

Abstract:

Carbonation is chemical process associated with CO2penetration into the material porous structure causing subsequent chemical changes in the structure of cement pastes. In this work, carbonation of several pastes containing varying amount of cement replacement by three waste ceramic powders is studied. Chemical composition of particular tested materials is accessed using XRF analysis. Matrix density, bulk density, total open porosity, compressive and bending strength are measured for all developed pastes with incorporated ceramic materials. Simultaneously, the effect of carbonation on these material properties is researched. The obtained results show significant improvement of materials mechanical strength due to the carbonation. Here, the measured compressive strength is typically about ~ 60% higher for materials exposed to CO2rich environment compared to the materials cured in laboratory conditions.

APA, Harvard, Vancouver, ISO, and other styles

20

Tao, Ren Guang, Qian Zhang, Hai Feng Liu, He Jiao Ma, and Shu Ing Doh. "Influence of Fly Ash Dosage and Desert Sand Replacement Ratio (DSRR) on the Carbonation Resistance of Concrete." Key Engineering Materials 912 (March 4, 2022): 77–92. http://dx.doi.org/10.4028/p-41d428.

Full text

Abstract:

Carbonation of concrete causes corrosion of the steel reinforcement and reduces the service life of the structure. Based on the reality that fly ash discharge is increasing year by year and construction sand is becoming increasingly limited, it is of practical importance to study the effect of fly ash dosage and desert sand replacement rate on the carbonation resistance of concrete. Orthogonal test L9(34) with four factors and three levels was designed to study the influence of water-binder ratio, fly ash dosage, sand ratio and DSRR on carbonation resistance of desert sand concrete (DSC). The results of the orthogonal tests were analysed by range analysis and ANOVA and a comparatively better concrete mix ratio was given. Next, single-factor tests were designed to investigate the effects of fly ash and desert sand replacement rates on the carbonation resistance of DSC respectively. The regression model among carbonation depth, fly ash dosage and DSRR was established. The experimental results show that the carbonation depth of concrete with fly ash as a single variable increases with the amount of fly ash, increasing more rapidly in the early stages than in the later stages. As the DSRR increases, the carbonation depth of concrete with desert sand as a single variable first decreases and then increases and reaches its lowest value when DSRR equals 20%. When fly ash and desert sand are mixed into concrete simultaneously, the carbonation depth reaches minimum value on the condition that fly ash dosage is 10% and DSRR is 20%.

APA, Harvard, Vancouver, ISO, and other styles

21

Huang, Guoping, Hui Wang, and Feiting Shi. "Coupling Effect of Salt Freeze-Thaw Cycles and Carbonation on the Mechanical Performance of Quick Hardening Sulphoaluminate Cement-Based Reactive Powder Concrete with Basalt Fibers." Coatings 11, no. 9 (September 20, 2021): 1142. http://dx.doi.org/10.3390/coatings11091142.

Full text

Abstract:

The effect of salt freeze-thaw cycles coupled with carbonation on the mechanical performance of quick hardening sulphoaluminate cement-based reactive powder concrete combined with basalt fibers was investigated. The ratios of basalt fibers in sulphoaluminate cement-based reactive powder concrete (SAC-RPC) were 1%, 2%, 3% and 4% by the volume of concrete. The mechanical strengths (compressive strength, flexural strength and bonding strength) of SAC-RPC were investigated after curing for 5 h, 1 d, 14 d and 28 d, respectively. Meanwhile, the mechanical strengths of resultant concrete were detected, when different NaCl freeze-thaw cycles and carbonation were adopted. Results showed that the addition of basalt fibers could effectively improve the mechanical strengths, especially the flexural strength of SAC-RPC. The dosage of 3.0% was the threshold value affected mechanical strengths. The flexural, compressive and bonding strengths of SAC-RPC were higher than 8.53 MPa, 34 MPa and 3.21 MPa, respectively. The mass loss and mechanical strengths loss of SAC-RPC increased in the form of quadratic function with the increasing number of NaCl freeze-thaw cycles and varied in the form of quadratic decreasing function. Meanwhile, the effect of carbonation on the mechanical strengths of SAC-RPC can be ignored. Additionally, the coupling effect of salt freeze-thaw cycles and carbonation could accelerate the attenuation of concrete strength. The mechanical strengths loss demonstrated a decreased quadratic function with the increasing volume of basalt fibers.

APA, Harvard, Vancouver, ISO, and other styles

22

Neves Junior, Alex, Romildo Dias Toledo Filho, Jo Dweck, and Eduardo de Moraes Rego Fairbairn. "Mechanical and Physical Properties of Early Carbonated High Initial Strength Portland Cement Pastes." Key Engineering Materials 634 (December 2014): 467–72. http://dx.doi.org/10.4028/www.scientific.net/kem.634.467.

Full text

Abstract:

After submitted to early age carbonation curing, mechanical and physical properties of high initial strength sulfate resistant Portland cement (HS SR PC) pastes were investigated, which were compared to those of non-carbonated reference pastes. Carbonation was performed for 1 and 24 hours, at the best conditions of CO2capturing, previously determined by the authors. Despite the compressive strength and elastic modulus of the 1h carbonated pastes were slightly higher than those of the reference pastes, their absorbed water content and porosity was slightly higher than that of the reference. In the case of 24h carbonation, its compressive strength decreases significantly because of its much higher porosity, although the new solid carbonated calcium silicate phase presents a much higher specific mass than those of the solid phases of the 1 hour and non-carbonated pastes.

APA, Harvard, Vancouver, ISO, and other styles

23

Wang, Jing, Dong Cui, and Xiao Bao Zuo. "A Review of Characterizing Methods for Carbonation in Cement-Based Materials." Key Engineering Materials 929 (August 24, 2022): 105–15. http://dx.doi.org/10.4028/p-4911du.

Full text

Abstract:

Concrete carbonation serves as one common durability issues in reinforced concrete structures at present. In order to understand the carbonation mechanism, many methods were developed by previous researchers for the characterization of concrete carbonation. For example, Phenolphthalein spraying method, Thermo-gravimetric analysis (TGA), X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), Mercury intrusion porosimetry (MIP), etc.. In this paper, all existed carbonation methods were summarized, and, based on the parameter (pH value inside pores, microstructure, chemical composition, etc. ) each method focuses, the function behind method was elaborated. Finally, this paper discussed the pros and cons of current methods, and further developing directions were proposed.

APA, Harvard, Vancouver, ISO, and other styles

24

Yao, Wu, Yu Kun Yang, and Meng Xue Wu. "Greenhouse Effect Reduction through Sustainable Magnesium Oxide Eco-Cement Products." Key Engineering Materials 680 (February 2016): 472–76. http://dx.doi.org/10.4028/www.scientific.net/kem.680.472.

Full text

Abstract:

Portland cement production leads to significant carbon dioxide emission and greenhouse effect. Magnesium oxide eco-cement, which is a mixture of Portland cement, magnesium oxide and fly ash, may be an alternative production. In this paper, the issue is focused on the carbon dioxide absorption ability and mechanical performance of this eco-cement. Several mix proportions of eco-cement were designed to conduct forced carbonation, strength and expansion tests. Also, microstructure analysis after carbonation was conducted. The results indicate that magnesium oxide eco-cement can efficiently absorb carbon dioxide and carbonation can improve mechanical performance substantially, also expansion of the eco-cement is found to fall within the safe limits and possesses good stability and soundness.

APA, Harvard, Vancouver, ISO, and other styles

25

Zhang, Hongzhi, Claudia Romero Rodriguez, Hua Dong, Yidong Gan, Erik Schlangen, and Branko Šavija. "Elucidating the Effect of Accelerated Carbonation on Porosity and Mechanical Properties of Hydrated Portland Cement Paste Using X-Ray Tomography and Advanced Micromechanical Testing." Micromachines 11, no. 5 (April 29, 2020): 471. http://dx.doi.org/10.3390/mi11050471.

Full text

Abstract:

Carbonation of hydrated cement paste (HCP) causes numerous chemo–mechanical changes in the microstructure, e.g., porosity, strength, elastic modulus, and permeability, which have a significant influence on the durability of concrete structures. Due to its complexity, much is still not understood about the process of carbonation of HCP. The current study aims to reveal the changes in porosity and micromechanical properties caused by carbonation using micro-beam specimens with a cross-section of 500 μm × 500 μm. X-ray computed tomography and micro-beam bending tests were performed on both noncarbonated and carbonated HCP micro-beams for porosity characterization and micromechanical property measurements, respectively. The experimental results show that the carbonation decreases the total porosity and increases micromechanical properties of the HCP micro-beams under the accelerated carbonation. The correlation study revealed that both the flexural strength and elastic modulus increase linearly with decreasing porosity.

APA, Harvard, Vancouver, ISO, and other styles

26

Zhao, Jun, Eskinder Desta Shumuye, Zike Wang, and Gashaw Assefa Bezabih. "Performance of GGBS Cement Concrete under Natural Carbonation and Accelerated Carbonation Exposure." Journal of Engineering 2021 (March 27, 2021): 1–16. http://dx.doi.org/10.1155/2021/6659768.

Full text

Abstract:

One of the primary problems related to reinforced concrete structures is carbonation of concrete. In many cases, depth of carbonation on reinforced concrete structures is used to evaluate concrete service life. Factors that can substantially affect carbonation resistance of concrete are temperature, relative humidity, cement composition, concentration of external aggressive agents, quality of concrete, and depth of concrete cover. This paper investigates the effect of varying the proportions of blended Portland cement (ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBS)) on mechanical and microstructural properties of concrete exposed to two different CO2 exposure conditions. Concrete cubes cast with OPC, and various percentages of GGBS (0%, 30%, 50%, and 70%) were subjected to natural (indoor) and accelerated carbonation exposure. The aim of this paper is to present the research findings and authenticate the literature results of carbonation by using GGBS cement in partial replacement of OPC. The concretes with OPC are compared to concretes with various percentages of GGBS, to assess the carbonation depth as well as rate of carbonation of GGBS-based concretes, under both accelerated carbonation and natural carbonation exposure conditions. Even though GGBS cement increases the carbonation depth, the results are not the same with different GGBS replacement percentages. A correlation is made between concrete samples exposed to 15 ± 2% carbon dioxide (CO2) concentration and those exposed to natural CO2 concentration. The results reveal that the products formed by carbonation are similar under both exposure conditions. The experimental tests also revealed that GGBS cement concrete has a lower carbonation resistance than OPC concrete, due to the consumption of portlandite by the pozzolanic reaction. The combination of 70% OPC and 30% GGBS behaved well enough with respect to accelerated carbonation exposure, the depth of carbonation being roughly equivalent to that of control group (100% OPC). The results also show that rate of carbonation becomes more sensitive as the percentage of GGBS replacement increases (binder ratio), rather than duration of curing. Concretes exposed to natural carbonation (indoor) achieved lower carbonation rates than those exposed to accelerated carbonation.

APA, Harvard, Vancouver, ISO, and other styles

27

Tu, Kun, Jin Wu, Yiyuan Wang, Huachao Deng, and Rui Zhang. "Uniaxial Compressive Stress–Strain Relation of Recycled Coarse Aggregate Concrete with Different Carbonation Depths." Materials 15, no. 15 (August 7, 2022): 5429. http://dx.doi.org/10.3390/ma15155429.

Full text

Abstract:

The stress–strain relation of recycled aggregate concrete (RAC) after carbonation is very important to the assessment of the durability of RAC. The objective of this study is to investigate the uniaxial compressive stress–strain curves of RAC after carbonation. In this study, the specimens were prepared with 70-mm diameter and 140-mm height cylinders, and the carbonation of the specimens was accelerated after curing 28 days. Then a uniaxial compressive loading test on the specimens was performed by using a mechanical testing machine. The results show that the peak stress (σ0) and elastic modulus (Ec) of all specimens increase with the increase of carbonation depth. The ratio of ultimate strain to peak strain (εu/ε0) and relative toughness of the specimens decrease with the increase of carbonation depth. Furthermore, carbonation has a stronger effect on natural coarse aggregate concrete (NAC) than the 50% replacement rate of RAC with similar compressive strength. Stress–strain models of recycled aggregate concrete with different carbonation depths were established according to experimental results.

APA, Harvard, Vancouver, ISO, and other styles

28

Goñi, S., M. T. Gaztañaga, and A. Guerrero. "Role of Cement Type on Carbonation Attack." Journal of Materials Research 17, no. 7 (July 2002): 1834–42. http://dx.doi.org/10.1557/jmr.2002.0271.

Full text

Abstract:

The carbonation of two hydrated ordinary portland cements of alkali content 1.03% or 0.43% Na2O equivalent and hydrated calcium aluminate cement (0.1% Na2O equivalent) was studied in a semi-dynamic atmosphere of 100% CO2, and 65% relative humidity at 20 ± 1 °C, for a period of 100 days. The changes of the microstructure before and during the carbonation were characterized by x-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. The kinetics of the process was evaluated from the total CaCO3 content by means of thermogravimetric analysis. The changes of the mechanical flexural strength were also studied. The pore solution was collected and analyzed before and after different periods of time. The results were compared with those obtained under natural carbonation conditions. The results showed that the alkali content of cement does not influence the kinetics of the process when the carbonation is accelerated. In the case of natural carbonation, an induction period is produced in the ordinary portland cement of low alkali content and calcium aluminate cement. The carbonation rate of calcium aluminate cement is the slowest for accelerated and natural carbonation.

APA, Harvard, Vancouver, ISO, and other styles

29

Schmidt, M. "Mechanical and thermal carbonation of strontium ferrite SrFeOx." Materials Research Bulletin 37, no. 13 (October 2002): 2093–105. http://dx.doi.org/10.1016/s0025-5408(02)00898-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

MIZUTANI, Yoshikatsu, Yoshinori KITSUTAKA, Koichi MATSUZAWA, and Yoshiyuki IEDA. "INFLUENCE OF CARBONATION ON MECHANICAL PROPERTIES OF ALC." Journal of Structural and Construction Engineering (Transactions of AIJ) 81, no. 728 (2016): 1619–25. http://dx.doi.org/10.3130/aijs.81.1619.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Cizer, Özlem, Koen Van Balen, and Dionys Van Gemert. "Competition between Hydration and Carbonation in Hydraulic Lime and Lime-Pozzolana Mortars." Advanced Materials Research 133-134 (October 2010): 241–46. http://dx.doi.org/10.4028/www.scientific.net/amr.133-134.241.

Full text

Abstract:

A combined reaction of hydration and carbonation takes place in hydraulic lime and lime-pozzolana mortars. Hydration reactions are the first reaction and carbonation of lime is the complementary reaction in the strength gain. Competition between these two reactions can occur in lime-pozzolana mortars if the pozzolanic material has low reactivity with lime, leading to the consumption of lime by carbonation reaction. The degree and the order of these reactions are strongly influenced by the moisture content. Hydration reactions are enhanced under moist conditions while carbonation is delayed. Curing under dry conditions does not sufficiently increase their strength because the hydration reactions are slowed down or even terminated by the full carbonation of lime in lime-pozzolana mortars. The consequence of this on the mechanical properties of the mortars is remarkable while the same impact is not observed in their porosity. Such mortars require moist conditions to ensure sufficient strength development.

APA, Harvard, Vancouver, ISO, and other styles

32

Wang, Kai, Liang Ren, and Luqing Yang. "Excellent Carbonation Behavior of Rankinite Prepared by Calcining the C-S-H: Potential Recycling of Waste Concrete Powders for Prefabricated Building Products." Materials 11, no. 8 (August 19, 2018): 1474. http://dx.doi.org/10.3390/ma11081474.

Full text

Abstract:

Pure rankinite (C3S2) was prepared by calcining a C-S-H gel precursor at a temperature of 1300 °C. The carbonation hardening behavior of the resulting rankinite was revealed by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetry and differential thermal analysis (TG/DTA), and scanning electron microscope (SEM) coupled with energy dispersive spectrum (EDS). The results indicate that the pure rankinite can be easily prepared at a lower temperature. The cubic compressive strengths of the resulting rankinite samples reach a value of 62.5 MPa after 24 h of carbonation curing. The main carbonation products formed during the carbonation process are crystalline calcite, vaterite and highly polymerized amorphous silica gels. The formed carbonation products fill the pores and bind to each other, creating a dense microstructure, which contributes to the excellent mechanical strength. These results provide a novel insight into potential recycling of waste concrete powders for prefabricated building products with lower CO2 emissions.

APA, Harvard, Vancouver, ISO, and other styles

33

Almeida, Filipe, Nuno Cristelo, Tiago Miranda, Castorina S. Vieira, Maria De Lurdes Lopes, and Fernando Castro. "Alkali-Activated Fly Ashes: Influence of Curing Conditions on Mechanical Strength." U.Porto Journal of Engineering 3, no. 2 (March 27, 2018): 57–67. http://dx.doi.org/10.24840/2183-6493_003.002_0006.

Full text

Abstract:

Alkaline activation of fly ashes is a procedure that enables an alternative binder which has been receiving much interest by several research groups particularly on the manufacturing of mortars and concretes. The properties of the materials that are developed during the alkaline activation are influenced by the curing conditions (temperature and relative humidity). Another relevant facet related to the curing procedures is the possibility of carbonation occur, which may have an impact on the mechanical strength of the alkaline cements. In this research, several sets of curing conditions were tested to understand which one results in a higher strength and reveals carbonation. Uniaxial compressive strength tests were conducted to assess mechanical behavior. The outcome suggests that higher temperature and low relative humidity yields higher mechanical strength.

APA, Harvard, Vancouver, ISO, and other styles

34

Zhang, Yingzi, Yanze Wang, Mingqian Yang, Huatao Wang, Guofang Chen, and Song Zheng. "Effect of Graphene Nanoplatelet on the Carbonation Depth of Concrete under Changing Climate Conditions." Applied Sciences 11, no. 19 (October 6, 2021): 9265. http://dx.doi.org/10.3390/app11199265.

Full text

Abstract:

Climate change has been unprecedented in the past decades or even thousands of years, which has had an adverse impact on the mechanical properties of concrete structures. Many researchers have begun to study new concrete materials. Graphene nanoplatelet (GNP) is an attractive nanomaterial that can change the crystal structure of concrete and improve durability. The aim of the present study was to investigate the effect of GNP (0.05%wt) on the carbonation depth of concrete under simulated changing climate conditions (varying temperature, relative humidity, and carbon dioxide (CO2) concentration), and compare it with ordinary concrete. When the concentration of CO2 is variable, the carbonation depth of graphene concrete is 10% to 20% lower than that of ordinary concrete. When the temperature is lower than 33 °C, the carbonation depth of graphene concrete is less than that of the control sample; however, above 33 °C, the thermal conductivity of GNP increases the carbonation reaction rate of concrete. When the humidity is a variable, the carbonation depth of graphene concrete is less than 15% to 30% of ordinary concrete, and when the humidity is higher than 78%, the difference in the carbonation depth between the ordinary concrete and the graphene concrete decreases gradually. The overall results indicated that GNP has a favorable effect on anti-carbonation performance under changing climate conditions.

APA, Harvard, Vancouver, ISO, and other styles

35

Chen, Cheng Chung, Chao Shi Chen, Jyun Yong Jhan, and Ming Sheng Ko. "The Improve of Accelerated Carbonation on Engineering Properties of Basic Oxygen Furnace Slag." Key Engineering Materials 709 (September 2016): 42–45. http://dx.doi.org/10.4028/www.scientific.net/kem.709.42.

Full text

Abstract:

Basic oxygen furnace (BOF) slag is characterized by high hardness, low abrasion, and high roughness. It is suitable as graded aggregate for engineering applications. However, the conversion process generated a great amount of unreacted free CaO, resulting in expansion and thus making the slag inconvenient for use in engineering applications. Accelerated carbonation of BOF slag is equivalent to natural weathering. Moreover, it can effectively shorten the weathering time. This study found that accelerated carbonation not only reduce expansion behaviors but also strengthen physical and mechanical properties. According to test results, the abrasion resistant, soundness, California bearing ratio, shear strength, and compressive strength have increased after carbonation.

APA, Harvard, Vancouver, ISO, and other styles

36

Yi, Yaolin, Kaiwen Lu, Songyu Liu, and Abir Al-Tabbaa. "Property changes of reactive magnesia–stabilized soil subjected to forced carbonation." Canadian Geotechnical Journal 53, no. 2 (February 2016): 314–25. http://dx.doi.org/10.1139/cgj-2015-0135.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

37

Kapetanaki, Kali, Chrysi Kapridaki, and Pagona-Noni Maravelaki. "Nano-TiO2 in Hydraulic Lime–Metakaolin Mortars for Restoration Projects: Physicochemical and Mechanical Assessment." Buildings 9, no. 11 (November 19, 2019): 236. http://dx.doi.org/10.3390/buildings9110236.

Full text

Abstract:

In recent years, lime mortars mixed with artificial or natural pozzolans are commonly used in restoration applications. The aim of this work is the assessment of carbonation, pozzolanic reaction, setting time, and mechanical properties of metakaolin–lime mortars mixed with crystalline nano-titania (nT) as additive. The studied mortars consist of hydrated lime and metakaolin in 60/40 ratio (wt%) and fine aggregates of either carbonate or silicate sand. The concentration of the nano-titania is equal to 6 (wt%) of the binder. For comparison purposes, three types of mortars and pastes are designed: Without the addition of nano-titania, with nT activated or not under UV irradiation. The evaluation of the carbonation and pozzolanic reaction over a 1.5-year curing period is carried out through thermal analysis (DTA/TG), infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). The uniaxial compression and the three-point bending tests at 28 days, 3 months, and 6 months were carried out to evaluate mechanical properties. The addition of activated nano-titania, due to an increased photocatalytic activity, accelerated the setting of the mortars, improving at the same time the mechanical properties. The plastic behavior of the lime–metakaolin mortars with activated nT was attributed to the evolution of carbonation and pozzolanic reaction.

APA, Harvard, Vancouver, ISO, and other styles

38

SANTOS, B. S., D. D. M. ALBUQUERQUE, and D. V. RIBEIRO. "Effect of the addition of metakaolin on the carbonation of Portland cement concretes." Revista IBRACON de Estruturas e Materiais 13, no. 1 (February 2020): 1–18. http://dx.doi.org/10.1590/s1983-41952020000100002.

Full text

Abstract:

Abstract Carbonation has been a concern of constructors and researchers because, by lowering the pH of the interstitial solution of the concrete, it can favor the post-deposition and subsequent corrosion of reinforced concrete reinforcement. Among the factors that influence carbonation is the use of pozzolanic materials, such as metakaolin. However, there is no consensus as to the positive or negative contribution of these additions. This work evaluated the influence of metakaolin on the mechanical properties, porosity and in particular on the carbonation of concrete, from the addition of 0%, 5%, 10% and 15% of metakaolin, in relation to the cement mass. From the results, it was observed that the addition of metakaolin, while not significantly influencing the porosity, gave the concrete a greater resistance to axial compression, a decrease in the capillary absorption and delayed the advance of the carbonation front in the concrete.

APA, Harvard, Vancouver, ISO, and other styles

39

Tam, Vivian WY, Anthony Butera, and Khoa N. Le. "Mechanical properties of CO2 concrete utilising practical carbonation variables." Journal of Cleaner Production 294 (April 2021): 126307. http://dx.doi.org/10.1016/j.jclepro.2021.126307.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Liu, Kaiwei, Wanyu Xu, Daosheng Sun, Jinhui Tang, Aiguo Wang, and Dong Chen. "Carbonation of recycled aggregate and its effect on properties of recycled aggregate concrete: A review." Materials Express 11, no. 9 (September 1, 2021): 1439–52. http://dx.doi.org/10.1166/mex.2021.2045.

Full text

Abstract:

The over exploitation of stone quarries, the generation of construction and demolition (C&D) waste, and the steady increase in the cost of preparing additional landfill space have caused great challenges to the environment and economy. Recycled aggregate concrete (RAC), as one of the sustainable construction material, has become a research hotspot and has received widespread attention. However, the formation of weak interface transition zone (ITZ) which caused by the existence of residual old mortar will exert a negative impact on the performance of RAC. Therefore, various treatments have been proposed to enhance the properties of the residual old mortar, including mechanical treatment, soaking, carbonation and so on. And it has been proved that carbonation is an effective and sustainable way to both improve the water absorption of RA and strengthen the ITZ of RAC. So, firstly, this article is devoted to reviewing the current research on the application of carbonized RA to RAC, focusing on two parts: (1) RA: the changes of physical properties under different conditions; (2) RAC: the microstructure, workability, mechanical properties and durability of the concrete with carbonized RA. Thereafter, it is known from the summarized literatures that carbonation can improve physical properties of RA and the optimal effect can be achieved by adjusting carbonation conditions. RAC with carbonized RA has denser both new and old ITZs, the microstructure, performance of it are also improved. Finally, this work may provide a reference for the research of carbonation and the application of RA in engineering in the future.

APA, Harvard, Vancouver, ISO, and other styles

41

Cao, Su Qing, Xiao Fei Xin, and Mei Yang. "The Analysis on the Mechanical Property and Durability of Carbon Fiber Reinforced Concrete." Advanced Materials Research 194-196 (February 2011): 869–72. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.869.

Full text

Abstract:

This paper mainly studies the influence pattern of mechanical properties and anti-permeability and carbonation etc durability after adding the carbon fiber into the concrete. Results show that appropriate amount fiber seep into concrete can improve its mechanical properties and durability.

APA, Harvard, Vancouver, ISO, and other styles

42

Duc Van, Nguyen, Emika Kuroiwa, Jihoon Kim, Hyeonggil Choi, and Yukio Hama. "Influence of Restrained Condition on Mechanical Properties, Frost Resistance, and Carbonation Resistance of Expansive Concrete." Materials 13, no. 9 (May 5, 2020): 2136. http://dx.doi.org/10.3390/ma13092136.

Full text

Abstract:

This paper presents the results of an experimental investigation of the effect of the restrained condition on the mechanical properties, frost resistance, and carbonation resistance of expansive concrete with different water–binder ratios. In this study, length change ratio test, expansion strain test, compressive strength test, mercury intrusion porosimetry test, underwater weighing test, freezing–thawing test, and accelerated carbonation test were performed to evaluate the mechanical properties, pore size distribution, total porosity, and durability of expansive concrete under both restrained and unrestrained conditions. The test results indicate that the length change ratio and expansion strain of the expansive concrete were controlled by the restrained condition. The compressive strength of expansive concrete was enhanced by the triaxial restraining when the amount of expansive additive was 40 kg/m3 of concrete. Two hypotheses were described to explain the change of pore structure change expansive mortar. The results also indicate that the carbonation resistance and frost resistance were improved by the uniaxial restrained condition. Furthermore, the effect of the restrained condition must be considered to evaluate not only the experimental results of the expansive concrete with a high EX replacement level but also the expansive concrete combining other cement replacement materials.

APA, Harvard, Vancouver, ISO, and other styles

43

Na, Hao, Yajun Wang, Xi Zhang, Junguo Li, Yanan Zeng, and Pengyao Liu. "Hydration Activity and Carbonation Characteristics of Dicalcium Silicate in Steel Slag: A Review." Metals 11, no. 10 (October 4, 2021): 1580. http://dx.doi.org/10.3390/met11101580.

Full text

Abstract:

Dicalcium silicate is one of the main mineral phases of steel slag. Ascribed to the characteristics of hydration and carbonation, the application of slag in cement production and carbon dioxide sequestration has been confirmed as feasible. In the current study, the precipitation process of the dicalcium silicate phase in steel slag was discussed. Meanwhile, the study put emphasis on the influence of different crystal forms of dicalcium silicate on the hydration activity and carbonation characteristics of steel slag. It indicates that most of the dicalcium silicate phase in steel slag is the γ phase with the weakest hydration activity. The hydration activity of γ-C2S is improved to a certain extent by means of mechanical, high temperature, and chemical activation. However, the carbonation activity of γ-C2S is about two times higher than that of β-C2S. Direct and indirect carbonation can effectively capture carbon dioxide. This paper also summarizes the research status of the application of steel slag in cement production and carbon dioxide sequestration. Further development of the potential of dicalcium silicate hydration activity and simplifying the carbonation process are important focuses for the future.

APA, Harvard, Vancouver, ISO, and other styles

44

Huang, Ying, Zhi Heng Deng, Yue Feng Hu, and Hui Xu. "Influence of Incorporating Recycled Aggregate on Carbonation Performance of Recycled Concrete." Applied Mechanics and Materials 193-194 (August 2012): 882–86. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.882.

Full text

Abstract:

Recycled concrete is a kind of green and new material. With the application of construction, more research should be carried on its carbonization performance, not only focusing on its mechanical properties. Recycled concretes with different W/C (0.45、0.55 and 0.65) and recycled aggregate mix proportions (0、30%、50%、70%and 100%) are made to test their carbonation depth. The results show that water-cement ratio and recycled aggregate mix proportions have interactive influence on carbonization performance of recycled concrete. Influence of recycled aggregate on carbonation depth depends on two conflicting aspects: one is beneficial effect due to high water absorption; another is harmful effect caused by damage structure. A new model of RAC carbonation depth is suggested based on the study.

APA, Harvard, Vancouver, ISO, and other styles

45

Li, Gang Lin, Zong Hui Zhou, and Xin Cheng. "Green Manufacture of Building Bricks by Carbonating Steel Slags." Advanced Materials Research 1073-1076 (December 2014): 1313–16. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.1313.

Full text

Abstract:

Carbon dioxide emission and industrial waste recycling have become hot spots of the world's scientific research, and the preparation of brick in CO2 mineral carbonation of steel slag increased gradually. However, there still exists some questions, such as low strength, low carbonization efficiency. Combined with these problems and according to the previous experimental basis, this study aims to further improve the carbonation efficiency and mechanical properties of building materials. In this paper, it studied the influence of carbonization pressure in the preparation of steel slag bricks as building materials by CO2 mineral carbonation. The results show that the optimal carbonization pressure is about 0.25MPa. Under the process parameters, the carbonization efficiency and the compressive strength is 16.6% and 65.1MPa respectively.

APA, Harvard, Vancouver, ISO, and other styles

46

Merta, Ildiko, Bojan Poletanovic, Jelena Dragas, Vedran Carevic, Ivan Ignjatovic, and Miroslav Komljenovic. "The Influence of Accelerated Carbonation on Physical and Mechanical Properties of Hemp-Fibre-Reinforced Alkali-Activated Fly Ash and Fly Ash/Slag Mortars." Polymers 14, no. 9 (April 28, 2022): 1799. http://dx.doi.org/10.3390/polym14091799.

Full text

Abstract:

The physical and mechanical properties of hemp-fibre-reinforced alkali-activated (AA) mortars under accelerated carbonation were evaluated. Two matrices of different physical and chemical properties, i.e., a low Ca-containing and less dense one with fly ash (FA) and a high Ca-containing and denser one with FA and granulated blast furnace slag (GBFS), were reinforced with fibres (10 mm, 0.5 vol% and 1.0 vol%). Under accelerated carbonation, due to the pore refinement resulting from alkali and alkaline earth salt precipitation, AA hemp fibre mortars markedly (20%) decreased their water absorption. FA-based hemp mortars increased significantly their compressive and flexural strength (40% and 34%, respectively), whereas in the denser FA/GBFS matrix (due to the hindered CO2 penetration, i.e., lower chemical reaction between CO2 and pore solution and gel products), only a slight variation (±10%) occurred. Under accelerated carbonation, embrittlement of the fibre/matrix interface and of the whole composite occurred, accompanied by increased stiffness, decreased deformation capacity and loss of the energy absorption capacity under flexure. FA-based matrices exhibited more pronounced embrittlement than the denser FA/GBFS matrices. A combination of FA/GBFS-based mortar reinforced with 0.5 vol% fibre dosage ensured an optimal fibre/matrix interface and stress transfer, mitigating the embrittlement of the material under accelerated carbonation.

APA, Harvard, Vancouver, ISO, and other styles

47

Kamaitis, Zenonas. "DAMAGE TO CONCRETE BRIDGES DUE TO REINFORCEMENT CORROSION." TRANSPORT 17, no. 5 (October 31, 2002): 163–70. http://dx.doi.org/10.3846/16483840.2002.10414037.

Full text

Abstract:

The mechanisms of reinforcement corrosion in concrete are the subject of extensive research. Although reliable methods for predicting the corrosive deterioration of concrete structures do not yet exist. This paper describes the durability problem of reinforced concrete bridges based on the mechanisms of carbonation depth or chloride profile. The deterioration model considering concrete carbonation, chloride penetration and concrete cover cracking is adopted to describe the service life of concrete structures. The corrosion models include environmental conditions, concrete carbonation or chloride diffusion rates, quality of concrete cover, steel corrosion rates and many other factors that make the predicting of service life of structures extremely difficult. Finally, the author gives the details of the methods of durabilio/ verification and the proposals for its including in the national standards and practical guides.

APA, Harvard, Vancouver, ISO, and other styles

48

Romero-Hermida, María Isabel, Antonio María Borrero-López, Vicente Flores-Alés, Francisco Javier Alejandre, José María Franco, Alberto Santos, and Luis Esquivias. "Characterization and Analysis of the Carbonation Process of a Lime Mortar Obtained from Phosphogypsum Waste." International Journal of Environmental Research and Public Health 18, no. 12 (June 21, 2021): 6664. http://dx.doi.org/10.3390/ijerph18126664.

Full text

Abstract:

This work addresses the reuse of waste products as a raw material for lime putties, which are one of the components of mortar. 1:3 Lime/sand mortars very similar to conventional construction mortars were prepared using a lime putty obtained from the treatment of phosphogypsum with sodium hydroxide. The physical, rheological and mechanical properties of this phosphogypsum-derived mortar have been studied, as well as the mineralogical composition, microstructure by scanning electron microscope (SEM) and curing process by monitoring carbonation and ultrasonic propagation velocity. Considering the negative influence of sulphates on the hardened material, the behaviour of the material after sulphates precipitation by adding barium sulphate was additionally tested. Carbonation progressed from the outside to the inside of the specimen through the porous system by Liesegang rings patterns for mortars with soluble sulphates, while the carbonation with precipitated sulphates was controlled by diffusion-precipitation. Overall, the negative influence of low-sulphate contents on the mechanical properties of mortars was verified. It must be highlighted the importance of their precipitation to obtain adequate performance.

APA, Harvard, Vancouver, ISO, and other styles

49

Bauerová, Pavla, Pavel Reiterman, Magdalena Kracík Štorkánová, and Martin Keppert. "Mechanical Properties of Reproduced Historic Mosaic Mortar." Solid State Phenomena 325 (October 11, 2021): 86–91. http://dx.doi.org/10.4028/www.scientific.net/ssp.325.86.

Full text

Abstract:

Mortars containing linseed oil as admixture to lime were identified in several mosaics found in Czech Republic. These mosaics were made around 1900 and the composition of their bedding mortar was likely influenced by publication La Mosaïque by E. Gerspach [1], published in Paris, 1880. The recipe for lime mortar with linseed oil and stand oil has been reproduced within the present paper. Four mixes were prepared with varying oil/stand oil content (below, above and according to Gerspach’s recommendation). The primary motivation of mosaic artists to use oil admixture was to keep the mortar’s plasticity for longer time, what is beneficial for the mosaic tesseraes (stones) adjustment. This effect was quantified by help of Vicat apparatus. The influence of oils on mechanical properties and carbonation was evaluated at 28 days. It was found by XRD, that the rate of carbonation is reduced due to the oil presence. It is caused by fact that the oil acts also as water-repealing admixture what reduces the ability of aerial CO2 to dissolve in pore solution and react with lime. The deformation behavior of material has been modified by oil toward the higher toughness, but lower compressive strength, due to polymeration of oil in mortar.

APA, Harvard, Vancouver, ISO, and other styles

50

Jain, Neeraj, Mridul Garg, and A. K. Minocha. "Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties." Journal of Waste Management 2015 (February 2, 2015): 1–8. http://dx.doi.org/10.1155/2015/281043.

Full text

Abstract:

Present investigations deal with the development of green concrete (M 30 grade) using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100%) with recycled coarse aggregate on various mechanical and durability properties of hardened concrete were discussed and compared with controls at different w/c ratio. Improvements in all the engineering properties of hardened concrete were observed using washed recycled coarse aggregates. The compressive strength of 28-day hardened concrete containing 100% washed recycled aggregate was slightly lower (7%) than concrete prepared with natural aggregates. Water absorption, carbonation, and rapid chloride penetration test were conducted to assess the durability of the concrete. Concrete was found moderately permeable for chloride ions penetration and no carbonation was observed in all the concrete mixes studied.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Mechanical carbonation'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles