Artykuły w czasopismach: „Self desiccation”

1

Jensen, O. Mejlhede. "Thermodynamic limitation of self-desiccation". Cement and Concrete Research 25, nr 1 (styczeń 1995): 157–64. http://dx.doi.org/10.1016/0008-8846(94)00123-g.

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Yu, Wei Wei, Qing Xiong, Yun Yu i Hang Lin. "Research on Self-Desiccation at early Age of High Performance Concrete with Polypropylene Fiber". Advanced Materials Research 374-377 (październik 2011): 1827–30. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.1827.

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This paper focuses on the impact which polypropylene fiber (PF) has on the self-desiccation effect at early age of high performance concrete (HPC). The experimental results indicate that PF has little influence on the Internal Relative Humidity (IRH) caused by self-desiccation effect of concrete, but can reduce early aged self-desiccation shrinkage of concrete. With the PF dosage increasing, the values of early self-desiccation shrinkage of HPC decrease first and then increase. In the experimental conditions, the value of self-desiccation shrinkage of concrete with 0.6Kg/m3 PF is the lowest one.

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Yang, Quan-bing, i Shu-qing Zhang. "Self-desiccation mechanism of high-performance concrete". Journal of Zhejiang University-SCIENCE A 5, nr 12 (grudzień 2004): 1517–23. http://dx.doi.org/10.1631/jzus.2004.1517.

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Zheng-wu, Jiang, Sun Zhen-ping i Wang Pei-ming. "Self-desiccation effect of high performance concrete". Journal of Wuhan University of Technology-Mater. Sci. Ed. 19, nr 4 (grudzień 2004): 82–86. http://dx.doi.org/10.1007/bf02841377.

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Wilson, Cameron, i W. Jason Weiss. "Improving the Durability of High Early Strength (HES) Concrete Patching Materials for Concrete Pavements". Transportation Research Record: Journal of the Transportation Research Board 2674, nr 8 (1.07.2020): 12–23. http://dx.doi.org/10.1177/0361198120917374.

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High early strength (HES) concrete patching materials are increasingly used to repair damaged pavements. The use of HES concrete enables the repaired pavement to be opened to traffic shortly after the repair has been installed; for example, opening pavements to traffic 4–6 h after the concrete is placed is becoming more common. HES concrete mixtures are typically designed with a low water-to-cement ratio and a high cement content; they contain accelerating admixtures and limited supplementary cementitious materials. As a result, these HES patches may be susceptible to self-desiccation, causing autogenous shrinkage and early age cracking. Self-desiccation can lead to reduced hydration, limited strength gain, and overestimation of strength development in maturity-based predictions. The objectives of this study are threefold. First, the paper will illustrate how self-desiccation can lead to the premature cessation of hydration and increased potential for shrinkage cracking. Second, the paper will illustrate how maturity-based predictions can be modified to account for self-desiccation. Third, internal curing is discussed as a way to mitigate self-desiccation and shrinkage ultimately improving the performance of HES concrete patching materials.

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6

Persson, Bertil. "Self-desiccation and its importance in concrete technology". Materials and Structures 30, nr 5 (czerwiec 1997): 293–305. http://dx.doi.org/10.1007/bf02486354.

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Zhang, Yong, Xiaowei Ouyang i Zhengxian Yang. "Microstructure-Based Relative Humidity in Cementitious System Due to Self-Desiccation". Materials 12, nr 8 (13.04.2019): 1214. http://dx.doi.org/10.3390/ma12081214.

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The internal relative humidity (RH) plays a crucial role in most of the concrete properties. Self-desiccation caused by continuous cement hydration is a major factor affecting the RH of concrete. This paper investigates the relationship between RH and microstructure for cementitious systems in the case of self-desiccation. A series of paste specimens prepared with different binder and water-binder-ratio (w/b) were cured under sealed conditions from 1 day to 1.5 years. The RH and microstructure of the paste specimens were measured. The microstructure characteristics under study include porosity, pore size, evaporable and non-evaporable water content. The results reveal that the RH of cementitious system drops to a great extent in the first 105 days’ hydration and decreases slowly afterwards. The blended materials such as fly ash, slag or limestone powder have different influences on the RH. A mathematical model between RH and the average pore diameter is proposed for cementitious systems under self-desiccation, regardless of age, w/b or cement type.

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Cui, Liang, i Mamadou Fall. "Modeling of self-desiccation in a cemented backfill structure". International Journal for Numerical and Analytical Methods in Geomechanics 42, nr 3 (3.11.2017): 558–83. http://dx.doi.org/10.1002/nag.2756.

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Persson, Bertil. "A NORDTEST method for verification of self-desiccation in concrete". Cement and Concrete Research 31, nr 2 (luty 2001): 199–203. http://dx.doi.org/10.1016/s0008-8846(00)00364-1.

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Kim, Jin-Keun, i Chil-Sung Lee. "Moisture diffusion of concrete considering self-desiccation at early ages". Cement and Concrete Research 29, nr 12 (grudzień 1999): 1921–27. http://dx.doi.org/10.1016/s0008-8846(99)00192-1.

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Helinski, Matthew, Andy Fourie, Martin Fahey i Mostafa Ismail. "Assessment of the self-desiccation process in cemented mine backfills". Canadian Geotechnical Journal 44, nr 10 (październik 2007): 1148–56. http://dx.doi.org/10.1139/t07-051.

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During the placement of fine-grained cemented mine backfill, the high placement rates and low permeability often result in undrained self-weight loading conditions, when assessed in the conventional manner. However, hydration of the cement in the backfill results in a net volume reduction—the volume of the hydrated cement is less than the combined volume of the cement and water prior to hydration. Though the volume change is small, it occurs in conjunction with the increasing stiffness of the cementing soil matrix, and the result in certain circumstances can be a significant reduction in pore-water pressure as hydration proceeds. In this paper, the implications of this phenomenon in the area of cemented mine backfill are explored. An analytical model is developed to quantify this behaviour under undrained boundary conditions. This model illustrates that the pore-water pressure change is dependent on the amount of volume change associated with the cement hydration, the incremental stiffness change of the soil, and the porosity of the material. Experimental techniques for estimating key characteristics associated with this mechanism are presented. Testing undertaken on two different cement–minefill combinations indicated that the rate of hydration and volumes of water consumed during hydration were unique for each cement–tailings combination, regardless of mix proportions.

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Chang, Hong-lei, i Zu-quan Jin. "Relation between humidity and chemically combined water under self-desiccation condition". Magazine of Concrete Research 69, nr 12 (czerwiec 2017): 641–48. http://dx.doi.org/10.1680/jmacr.16.00510.

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Barcelo, Laurent, Micheline Moranville i Bernard Clavaud. "Autogenous shrinkage of concrete: a balance between autogenous swelling and self-desiccation". Cement and Concrete Research 35, nr 1 (styczeń 2005): 177–83. http://dx.doi.org/10.1016/j.cemconres.2004.05.050.

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Utsumi, Hideyuki, Takehiro Misaka i Wataru Moteki. "Prediction Model of Internal Relative Humidity During Self-desiccation in Hardened Cement Pastes". Concrete Research and Technology 26 (2015): 11–19. http://dx.doi.org/10.3151/crt.26.11.

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Persson, B. "Consequence of cement constituents, mix composition and curing conditions for self-desiccation in concrete". Materials and Structures 33, nr 6 (lipiec 2000): 352–62. http://dx.doi.org/10.1007/bf02479644.

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Li, Wenchen, i Mamadou Fall. "Sulphate effect on the early age strength and self-desiccation of cemented paste backfill". Construction and Building Materials 106 (marzec 2016): 296–304. http://dx.doi.org/10.1016/j.conbuildmat.2015.12.124.

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Zhang, Xiao, i Hongduo Zhao. "Characterization of Moisture Diffusion in Cured Concrete Slabs at Early Ages". Advances in Materials Science and Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/154394.

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The objective of this paper is to investigate the characterization of moisture diffusion inside early-age concrete slabs subjected to curing. Time-dependent relative humidity (RH) distributions of three mixture proportions subjected to three different curing methods (i.e., air curing, water curing, and membrane-forming compounds curing) and sealed condition were measured for 28 days. A one-dimensional nonlinear moisture diffusion partial differential equation (PDE) based on Fick’s second law, which incorporates the effect of curing in the Dirichlet boundary condition using a concept of curing factor, is developed to simulate the diffusion process. Model parameters are calibrated by a genetic algorithm (GA). Experimental results show that the RH reducing rate inside concrete under air curing is greater than the rates under membrane-forming compound curing and water curing. It is shown that the effect of water-to-cement (w/c) ratio on self-desiccation is significant. Lower w/c ratio tends to result in larger RH reduction. RH reduction considering both effect of diffusion and self-desiccation in early-age concrete is not sensitive to w/c ratio, but to curing method. Comparison between model simulation and experimental results indicates that the improved model is able to reflect the effect of curing on moisture diffusion in early-age concrete slabs.

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18

El-Zein, Abbas, Bowei Yu i Ali Ghavam-Nasiri. "Insights into Desiccation and Self-Healing of Bentonite in Geosynthetic Clay Liners under Thermal Loads". E3S Web of Conferences 92 (2019): 03006. http://dx.doi.org/10.1051/e3sconf/20199203006.

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Geosynthetic Clay Liners (GCLs) are widely used for protecting groundwater from pollution sources at the surface, including applications in which they are subject to significant thermal gradients. Hence, sodium bentonite in the GCL may undergo significant dehydration and cracking, and the GCL might fail as a result. The paper presents outcomes of a set of recent experimental and numerical investigations exploring the propensity of bentonite to desiccate and self-heal, as well as means of mitigating the effect of thermal gradients on the hydraulic conductivity of GCLs. An elasto-plastic thermo-hydro-mechanical model was found to yield reasonable predictions of experimental behaviour, except for the transient phase of pre-heating hydration. Introducing an airgap between the GCL and the heat source can reduce the extent of desiccation and its effects on hydraulic conductivity. However, the effectiveness of the solution will depend on other factors including subgrade, magnitude of thermal and mechanical loads and type of GCL.

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Wyrzykowski, Mateusz, i Pietro Lura. "Effect of relative humidity decrease due to self-desiccation on the hydration kinetics of cement". Cement and Concrete Research 85 (lipiec 2016): 75–81. http://dx.doi.org/10.1016/j.cemconres.2016.04.003.

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Li, Kefei, Qiang Zeng, Mingyong Luo i Xiaoyun Pang. "Effect of self-desiccation on the pore structure of paste and mortar incorporating 70% GGBS". Construction and Building Materials 51 (styczeń 2014): 329–37. http://dx.doi.org/10.1016/j.conbuildmat.2013.10.063.

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Tian, Xichun, i Mamadou Fall. "Non-isothermal evolution of mechanical properties, pore structure and self-desiccation of cemented paste backfill". Construction and Building Materials 297 (sierpień 2021): 123657. http://dx.doi.org/10.1016/j.conbuildmat.2021.123657.

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22

Aili, Abudushalamu, Matthieu Vandamme, Jean-Michel Torrenti i Benoit Masson. "Is long-term autogenous shrinkage a creep phenomenon induced by capillary effects due to self-desiccation?" Cement and Concrete Research 108 (czerwiec 2018): 186–200. http://dx.doi.org/10.1016/j.cemconres.2018.02.023.

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Masoero, Enrico, Gianluca Cusatis i Giovanni Di Luzio. "C–S–H gel densification: The impact of the nanoscale on self-desiccation and sorption isotherms". Cement and Concrete Research 109 (lipiec 2018): 103–19. http://dx.doi.org/10.1016/j.cemconres.2018.04.014.

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Ding, Xiaoping, Jun Zhang i Jiahe Wang. "Integrative modeling on self-desiccation and moisture diffusion in concrete based on variation of water content". Cement and Concrete Composites 97 (marzec 2019): 322–40. http://dx.doi.org/10.1016/j.cemconcomp.2019.01.008.

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Pathirage, M., D. P. Bentz, G. Di Luzio, E. Masoero i G. Cusatis. "The ONIX model: a parameter-free multiscale framework for the prediction of self-desiccation in concrete". Cement and Concrete Composites 103 (październik 2019): 36–48. http://dx.doi.org/10.1016/j.cemconcomp.2019.04.011.

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26

Jiang, Zhengwu, Zhenping Sun i Peiming Wang. "Internal relative humidity distribution in high-performance cement paste due to moisture diffusion and self-desiccation". Cement and Concrete Research 36, nr 2 (luty 2006): 320–25. http://dx.doi.org/10.1016/j.cemconres.2005.07.006.

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Chen, Hui, Mateusz Wyrzykowski, Karen Scrivener i Pietro Lura. "Prediction of self-desiccation in low water-to-cement ratio pastes based on pore structure evolution". Cement and Concrete Research 49 (lipiec 2013): 38–47. http://dx.doi.org/10.1016/j.cemconres.2013.03.013.

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Rayhani, M. HT, E. K. Yanful i A. Fakher. "Desiccation-induced cracking and its effect on the hydraulic conductivity of clayey soils from Iran". Canadian Geotechnical Journal 44, nr 3 (1.03.2007): 276–83. http://dx.doi.org/10.1139/t06-125.

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Clay materials have many environmental applications, especially in situations where a hydraulic barrier is desired. However, as the plasticity of clay increases, cracks tend to develop during cycles of long dry spells. This is particularly a concern in the construction of covers or installation of landfill liners prior to waste filling. In the present study, specimens prepared from three natural clayey soils from Iran used for clay barrier construction, and one artificial clayey soil, were subjected to cycles of wetting and drying. Surface cracks of different dimensions formed as a result of drying. Specimens with the largest volumetric shrinkage strains typically contained the highest number of cracks. Specimens that developed cracks were subjected to hydraulic conductivity testing. The results showed that the dimension of cracks increased with increasing plasticity index and clay content and, so, the initial hydraulic conductivity increased with increasing plasticity index and cycles of drying and wetting. Cracking increased the hydraulic conductivity by 12–34 times, depending on the plasticity of the soil. After a long saturation time, the hydraulic conductivity of the soils decreased with an increase in saturation time, which could be associated with a self-healing process that affects the soils by different degrees.Key words: desiccation, cracking, plasticity, hydraulic conductivity, clay barriers, self-healing, volumetric shrinkage.

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Wang, Yong, Mamadou Fall i Aixiang Wu. "Initial temperature-dependence of strength development and self-desiccation in cemented paste backfill that contains sodium silicate". Cement and Concrete Composites 67 (marzec 2016): 101–10. http://dx.doi.org/10.1016/j.cemconcomp.2016.01.005.

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Li, Wenchen, i Mamadou Fall. "Strength and self-desiccation of slag-cemented paste backfill at early ages: Link to initial sulphate concentration". Cement and Concrete Composites 89 (maj 2018): 160–68. http://dx.doi.org/10.1016/j.cemconcomp.2017.09.019.

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Chang-wen, Miao, Tian Qian, Sun Wei i Liu Jia-ping. "Water consumption of the early-age paste and the determination of “time-zero” of self-desiccation shrinkage". Cement and Concrete Research 37, nr 11 (listopad 2007): 1496–501. http://dx.doi.org/10.1016/j.cemconres.2007.08.005.

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Stafford, Richard, Mark S. Davies i Gray A. Williams. "Self-Organization of Intertidal Snails Facilitates Evolution of Aggregation Behavior". Artificial Life 14, nr 4 (październik 2008): 409–23. http://dx.doi.org/10.1162/artl.2008.14.4.14401.

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Many intertidal snails form aggregations during emersion to minimize desiccation stress. Here we investigate possible mechanisms for the evolution of such behavior. Two behavioral traits (following of mucus trails, and crevice occupation), which both provide selective advantages to individuals that possess the traits over individuals that do not, result in self-organization of aggregations in crevices in the rock surface. We suggest that the existence of self-organizing aggregations provides a mechanism by which aggregation behavior can evolve. The inclusion of an explicitly coded third behavior, aggregation, in a simulated population produces patterns statistically similar to those found on real rocky shores. Allowing these three behaviors to evolve using an evolutionary algorithm, however, results in aggregation behavior being selected against on shores with high crevice density. The inclusion of broadcast spawning dispersal mechanisms in the simulation, however, results in aggregation behavior evolving as predicted on shores with both high crevice density and low crevice density (evolving in crevices first, and then both in crevices and on flat rock), indicating the importance of environmental interactions in understanding evolutionary processes. We propose that self-organization can be an important factor in the evolution of group behaviors.

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Aili, Abudushalamu, Matthieu Vandamme, Jean-Michel Torrenti i Benoit Masson. "Addendum to “Is long-term autogenous shrinkage a creep phenomenon induced by capillary effects due to self-desiccation?”". Cement and Concrete Research 115 (styczeń 2019): 568. http://dx.doi.org/10.1016/j.cemconres.2018.07.001.

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Lura, Pietro, Jon Couch, Ole Mejlhede Jensen i Jason Weiss. "Early-age acoustic emission measurements in hydrating cement paste: Evidence for cavitation during solidification due to self-desiccation". Cement and Concrete Research 39, nr 10 (październik 2009): 861–67. http://dx.doi.org/10.1016/j.cemconres.2009.06.015.

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Jin, Dan, Wu Yao i Yi Chen. "Relative Humidity of Blended Cement Pastes in Sealed during Hydration". Key Engineering Materials 539 (styczeń 2013): 60–63. http://dx.doi.org/10.4028/www.scientific.net/kem.539.60.

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As an important part of cement-based materials，water plays an important role during hydration and self-desiccation so the measurement of relative humidity or internal moisture in the research of cement-based materials is vital. In this paper, the measurement samples are blended cement pastes in sealed with different water to cement ratios and different kind of mineral admixtures. The measurement was taken at different ages during hydration to investigate the changes of relative humidity. The result showed that the water to cement ratio was the key factor of affecting the change of relative humidity, and the effect of mineral admixture kind was not very obvious in this experiment.

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Diane Knight, J. "Evaluation of Rhizobium inoculant formulations for alfalfa yield and N fixation". Canadian Journal of Plant Science 87, nr 2 (1.04.2007): 267–72. http://dx.doi.org/10.4141/p05-143.

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Because of its small seed size, alfalfa (Medicago sativa L.) typically is seeded at a shallow depth, putting Rhizobium inoculated onto the seed coat at a high risk of desiccation. Granular inoculants may provide a superior delivery formulation for Rhizobium because the inoculant can be placed deeper in the soil than the seed, where it is protected from desiccation. Sinorhizobium meliloti cv. Beaver delivered as (1) pre-inoculated alfalfa seed from the inoculant manufacturer, (2) commercial peat-based, self-sticking inoculant applied on-site, and (3) granular inoculant placed with the seed or (4) banded below and to the side of the seed was evaluated against uninoculated alfalfa controls at three field sites in Saskatchewan. Overall, alfalfa inoculated with the granular formulation placed below and to the side of the alfalfa seed was among the highest biomass producer in the establishment year, although it did not exhibit superior nodulation or biological N fixation compared with the other treatments. Any advantage conferred by the granular inoculant in the establishment year did not persist through the first and second production years. Under the conditions of this study, the delivery formulation had no long-term affect on alfalfa productivity, nodulation and biological N fixation. Furthermore, none of the inoculant treatments were consistently superior to the uninoculated controls. Key words: Alfalfa, granular inoculant, peat inoculant, pre-inoculated seed, Medicago sativa L., Sinorhizobium meliloti

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Jakhrani, Sadam Hussain, Jae Suk Ryou, Atta-ur-Rehman, In Kyu Jeon, Byeong Hun Woo i Hong Gi Kim. "Prevention of Autogenous Shrinkage in High-Strength Mortars with Saturated Tea Waste Particles". Materials 12, nr 17 (21.08.2019): 2654. http://dx.doi.org/10.3390/ma12172654.

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The purpose of this study was to prevent early age autogenous shrinkage in high-strength mortars with saturated tea waste particles. In general, high strength and high performance concretes are made with low water/binder ratios; hence, they are susceptible to shrink at early ages. This shrinkage occurs due to self-desiccation that leads to autogenous shrinkage. To overcome self-desiccation problems in high-strength cement composites, it is necessary to keep the composites moist for a long time. Pre-saturated porous lightweight aggregates and super absorbent polymers are the most commonly used materials in high-strength cement composites to keep them moist for a long time; however, in this study, porous tea waste particles were used to keep the cement mortars moist. Pre-saturated tea waste particles were used in two different size proportions, making up as much as 3% of the volume of the binder. Moreover, commonly used lightweight aggregate (perlite) was also used to compare the outcomes of specimens made with tea waste particles. Different parameters were observed, such as, flow of fresh mortars, autogenous shrinkage, mechanical strengths and microstructure of specimens. The addition of tea waste and perlite particles in mortars made with Ordinary Portland cement (OPC) as the only binder, showed a reduction in flow, autogenous shrinkage and mechanical strengths, as compared to mixes made with partial addition of silica fume. Although, the use of silica fume improved the mechanical strength of specimens. Moreover, the use of saturated tea waste and perlite particles also improved the microstructure of specimens at an age of 28 days. The results revealed that the saturated tea waste particles have the ability to prevent autogenous shrinkage but they reduce strength of high-strength mortars at early ages.

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Tian, Qian, Hang Zhang, Yu Jiang Wang, Fei Guo, Ting Yao i Ji Ping Liu. "Determining the Contact Angle of Hardened Cement Paste Using Thin Layer Wicking Method". Key Engineering Materials 539 (styczeń 2013): 184–88. http://dx.doi.org/10.4028/www.scientific.net/kem.539.184.

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Contact angle is a very important parameter to investigate the function mechanism of chemical admixtures as well as the capillary stress resulted from self-desiccation or drying. However, in most of the studies, it is only assumed to be 0 degrees. This paper studied the contact angle of hardened cement paste using thin wicking method. A serious of study was conducted on the influence of layer preparation, pre-contacting method, cement paste powder size, and suspension concentration on the measuring results. An optimized thin layer wicking method was proposed for determining the contact angle of hardened cement paste, which improves effectively the linear correlation of the penetration distance - time curve and satisfies the prerequisite of Washburn function.

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Simms, Paul, i Murray Grabinsky. "Direct measurement of matric suction in triaxial tests on early-age cemented paste backfill". Canadian Geotechnical Journal 46, nr 1 (styczeń 2009): 93–101. http://dx.doi.org/10.1139/t08-098.

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Hydration occurring in cemented paste backfill (CPB) is shown to generate matric suction through self-desiccation. This complicates determination of the water-retention curve and mechanical properties during curing, which are important in stope design, and renders problematic the use of axis-translation testing procedure to control suctions in strength testing. An alternative is to monitor suction directly during testing. To this end, a miniature tensiometer is inserted into the base of a triaxial cell. A series of unconfined and confined tests are performed on early-age (less than two weeks old) CPB. The observed behaviour is similar to that observed in weakly cemented soils, showing a distinct tendency to dilate during shearing.

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40

Miller, Don. "Lichens, wildfire, and caribou on the taiga ecosystem of northcentral Canada". Rangifer 20, nr 5 (1.04.2000): 195. http://dx.doi.org/10.7557/2.20.5.1644.

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Terrestrial lichens are unique organisms that are pioneers on bare sand and rock, survive desiccation and reproduce both sexually and asexually. They compete poorly with dense, aggressive vascular flora. Wildfires require organic matter as fuels, are the driving force in perpetuation of the Taiga Ecosystem in a heterogeneous environment and, if left alone, are self controlling. Caribou wintering on the Taiga are dependent on: (1) a terricolous lichen forage supply for most of the winter, (2) a heterogeneous environment to cope with predators and the changing nival environment, and (3) natural wildfires to supply these needs. Wildlife control on the Taiga winter range is not recommended as a management tool for barren-ground caribou.

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Dziedzic, Dilcele Silva Moreira, João Paulo Stanislovicz Prohny, Gledson Luiz Picharski i Adilson Yoshio Furuse. "Influence of curing protocols on water sorption and solubility of a self-adhesive resin-cement". Brazilian Journal of Oral Sciences 15, nr 2 (20.04.2017): 144. http://dx.doi.org/10.20396/bjos.v15i2.8648766.

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Aim: To evaluate the effect of different activation protocols on the polymerization of a self-adhesive dual cured resin-based cement. Methods: Thirty disc-shaped specimens were prepared with the resin cement RelyX U200 (3M ESPE) and divided according to three protocols: immediate light-activation for 40 s, delayed light-activation (10 min after manipulation, for 40 s) or self-curing without light-activation. The specimens were desiccated, kept in water at 37 °C for 7 days and desiccated again to calculate water sorption, solubility and mass variation. Data were analyzed by Shapiro-Wilk Test and Wilcoxon tests (α=0.05). Images after the specimens’ final desiccation were also made. Results: The Wilcoxon test revealed a significant difference for sorption and mass variation (p<0.05) and the highest value was observed in self-curing or chemical activation group (CA), followed by delayed light-activation (DL) and immediate light-activation (IL). Besides the water sorption parameters, there were also microvoids on the discs from the delayed and no light-activation groups. Conclusions: The light-activation immediately after manipulation is recommended for the evaluated resin cement.

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42

Li, Yue, i Qian Qian Yan. "Relationship between Internal Relative Humidity and Autogenous Shrinkage of Cement Paste with Supplementary Cementitious Materials (SCM)". Key Engineering Materials 539 (styczeń 2013): 35–39. http://dx.doi.org/10.4028/www.scientific.net/kem.539.35.

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The influence of water to binder (W/B), types and dosage of supplementary cementitious materials (SCM) on the internal relative humidity (IRH) and autogenous shrinkage (AS) of cement pastes caused by self-desiccation were investigated, and their relationship was discussed. The results show that, W/B is a main factor that affects IRH change and AS of cement pastes with SCM. With the decrease of W/B, IRH of cement pastes decreases, but AS of cement pastes increases. Different types and dosages of SCM affect the IRH differently; fly ash (FA) reduces AS, silica fume (SF) increases AS, and the effect of GBFS on AS is between FA and GBFS. The linear correlation between the change of IRH and AS of cement pastes with SCM is established.

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Klemm, Agnieszka J., i Fernando C. R. Almeida. "Towards more sustainable construction–application of superabsorbent polymers in cementitious matrices with reduced carbon footprint". MATEC Web of Conferences 149 (2018): 01019. http://dx.doi.org/10.1051/matecconf/201814901019.

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Construction industry is constantly searching for sustainable innovations to mitigate negative environmental impacts. Ground granulated blast-furnace slag (GGBS) is a well-known supplementary cementitious material which contributes to reduction of energy and CO2 emissions from cement industry. However, its use in cementitious systems leads to materials with high cracking susceptibility due to their greater autogenous shrinkage triggered by self-desiccation processes. This problem is even more pronounced when concrete is exposed to severe dry-hot weather conditions, such as in North Africa. In order to mitigate this negative effect of cracking, internal curing agents in the form of Superabsorbent polymers (SAP) can be successfully used. This approach leads to more durable cement based materials and in turn more sustainable constructions.

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Ferraris, C. F., E. J. Garboczi, F. L. Davis i J. R. Clifton. "The effect of stress relaxation, self-desiccation, and water absorption on the alkali-silica reaction in low watercement ratio mortars". Cement and Concrete Research 27, nr 10 (październik 1997): 1553–60. http://dx.doi.org/10.1016/s0008-8846(97)00171-3.

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Fontanelli, Marco, Michel Pirchio, Christian Frasconi, Luisa Martelloni, Michele Raffaelli, Andrea Peruzzi, Nicola Grossi i in. "Steaming and Flaming for Converting Cool-season Turfgrasses to Hybrid Bermudagrass in Untilled Soil". HortTechnology 27, nr 5 (październik 2017): 682–89. http://dx.doi.org/10.21273/horttech03773-17.

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Turfgrass species can be classified into two main groups: cool-season and warm-season species. Warm-season species are more suited to a Mediterranean climate. Transplanting is a possible method to convert a cool-season to a warm-season turfgrass in untilled soil. It generally requires the chemical desiccation of the cool-season turfgrass. However, alternative physical methods, like flaming and steaming, are also available. This paper compares flaming, steaming, and herbicide application to desiccate cool-season turfgrass, for conversion to hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) in untilled soil, using transplanting. Two prototype machines were used, a self-propelled steaming machine and a tractor-mounted liquefied petroleum gas flaming machine. Treatments compared in this work were two flaming treatments and two steaming treatments performed at four different doses together with two chemical treatments with glufosinate-ammonium herbicide applications. The cool-season turfgrass species were tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne). The desiccation effect of the various treatments on cool-season turf was assessed by photographic survey 15 days after treatment. The percentage cover of hybrid bermudagrass was visually assessed at 43 weeks after planting. Steaming and flaming effects on both parameters were described by logistic curves. The highest doses of steaming and flaming almost completely desiccated cool-season turf, and similar hybrid bermudagrass cover was established by both the methods as the chemical application (50% to 60%). Thus both flaming and steaming may be considered as valid alternatives to herbicides aimed at turf conversion.

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Aguiar, Thaiane Rodrigues, Carolina Bosso André, Gláucia Maria Boni Ambrosano i Marcelo Giannini. "The Effect of Light Exposure on Water Sorption and Solubility of Self-Adhesive Resin Cements". International Scholarly Research Notices 2014 (29.10.2014): 1–6. http://dx.doi.org/10.1155/2014/610452.

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Purpose. To investigate the effect of light activation on the water sorption (WS) and solubility (SL) of resin cements after 24 h and 7 days. Methods. Disk-shaped specimens were prepared using five dual-polymerized cements (four self-adhesive [RelyX Unicem, MaxCem, SeT and G-Cem] and one conventional [Panavia F 2.0]) and divided according to the curing mode (direct light exposure or self-cure) and water immersion period (24 h or 7 days). Specimens were dry-stored and weighed daily until a constant mass was recorded (M1). Then, specimens were stored in water for either 24 h or 7 days and immediately weighed (M2). After desiccation, specimens were weighed again until a constant mass was achieved (M3). WS and SL were calculated and statistically analyzed by Kruskal-Wallis, Dunn and Mann-Whitney U tests (α=0.05%). Results. There was a significant increase in WS for all products after one-week immersion in water. The highest water uptake was observed for autopolymerized groups. Extended water immersion significantly affected the SL for most of autopolymerized cements. Significant differences between products were observed in both tests. Conclusions. The curing mode and the water immersion period may affect the mechanical stability of the resin cements, and these differences appear to be product-dependent.

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Clements, Jeff C., Ellen Schagerström, Sam Dupont, Fredrik Jutfelt i Kirti Ramesh. "Roll, right, repeat: short-term repeatability in the self-righting behaviour of a cold-water sea cucumber". Journal of the Marine Biological Association of the United Kingdom 100, nr 1 (13.01.2020): 115–20. http://dx.doi.org/10.1017/s0025315419001218.

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AbstractFor many benthic marine invertebrates, inversion (being turned upside-down) is a common event that can increase vulnerability to predation, desiccation and unwanted spatial transport, and requires behavioural ‘self-righting’ to correct. While self-righting behaviour has been studied for more than a century, the repeatability (R) – the portion of behavioural variance due to inter-individual differences – of this trait is not well understood. Heritability and the evolution of animal behaviour rely on behavioural repeatability. Here, we examined the self-righting technique of a cold-water holothurid, Parastichopus tremulus, and assessed the repeatability of this behaviour. Under laboratory conditions, P. tremulus consistently used muscle contractions to curl its body and roll itself back to an upright position, which provided for rapid (x̅ ± SD = 96.7 ± 49.8 s) and highly repeatable (R = 0.75) self-righting in the short term that varied between individuals (range of individual average righting times = 34.8–217.0 s). Righting time tended to increase with animal size; however, substantial variation was evident at comparable sizes, as average righting time ranged from 34.8–155.5 s for animals ~20 cm in body length. Contrary to previous studies on other echinoderms, we found no evidence of improved righting times for P. tremulus over time. This study ultimately provides the first detailed documentation of self-righting behaviour for P. tremulus and suggests that this species displays a high degree of repeatability for this trait in the short term.

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Egloffstein, T. "Natural bentonitesâinfluence of the ion exchange and partial desiccation on permeability and self-healing capacity of bentonites used in GCLs". Geotextiles and Geomembranes 19, nr 7 (wrzesień 2001): 427–44. http://dx.doi.org/10.1016/s0266-1144(01)00017-6.

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Zaidi, Mohammed, Nasre-Dine Ahfir, Abdellah Alem, Said Taibi, Bouabid El Mansouri, Yongxiang Zhang i Huaqing Wang. "Use of X-ray computed tomography for studying the desiccation cracking and self-healing of fine soil during drying–wetting paths". Engineering Geology 292 (październik 2021): 106255. http://dx.doi.org/10.1016/j.enggeo.2021.106255.

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Jeong, J., P. Mounanga, Hamidreza Ramezani, Marwen Bouasker i D. Bassir. "New Approach of Multi Scale Modeling Based on the Hygro-Cosserat Theory for Self Desiccation Deformation of Cement Mortars at Early Age". Advanced Materials Research 123-125 (sierpień 2010): 563–66. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.563.

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In the present paper, we concentrate on the heterogeneous cement mortars and we treat them as Cosserat-based media. The autogenous shrinkage phenomenon at early age (from 1 up to 3 days after mixing) has been analyzed by means of Cosserat theory. The characteristic length scale parameter Lc in this theory helps us to change the size specimen from macro-scale to micro-scale using the theoretical size effect aspects. This methodology is also capable of treating cracks initiation and their appearance in the cementitious matrix surrounding the sand-inclusions, which should occurred inside of the Representative Volume Elementary (RVE) of mortar subjected to self-desiccation shrinkage during hydration at early age. By taking advantage of the Nonlinear Finite Element Analysis (NFEA), the numerical experiments have been performed. The numerical outcomes are well agreed with the experimental observations coming from Scanning Electronic Microscopy (SEM) images. It concludes that the inclusions create not only a hygro stress concentration around the grains but also the number of inclusions should influence the network in cementitous matrix.

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