The spatial variations of the soil hydraulic properties were mainly considered in vertical direction. The objectives of this study were to measure water-retention curves, θ（ψ）, and unsaturated hydraulic conductivi...The spatial variations of the soil hydraulic properties were mainly considered in vertical direction. The objectives of this study were to measure water-retention curves, θ（ψ）, and unsaturated hydraulic conductivity functions, K（ψ）, of the soils sampled at different slope positions in three directions, namely, in vertical direction, along the slope and along the contour, and to determine the effects of sampling direction and slope position of two soil catenas. At the upper slope positions, the surface soils （0-10 cm） sampled in the vertical direction had a lower soil water content, 0, at a certain soil water potential （-1 500 kPa 〈 ψ 〈 -10 kPa） and had the greatest unsaturated hydraulic conductivity, K, at ψ 〉 -10 kPa. At the lower slope positions, K at ψ〉 -10 kPa was smaller in the vertical direction than in the direction along the slope. The deep soils （100 110 cm） had similar soil hydraulic properties in all the three directions. The anisotropic variations of the hydraulic properties of the surface soils were ascribed to the effects of natural wetting and drying cycles on the structural heterogeneity. These results suggested that the anisotropy of soil hydraulic properties might be significant in influencing soil water movement along the slope and need to be considered in modeling.展开更多
研究添加聚丙烯酸钠(PAAS)对堆肥产品的吸水保水性能的影响.研究显示,PAAS能明显改善污泥结构;添加PAAS的堆肥产品吸水倍率可达到5.97 m L·g-1,吸水保水性能都优于未添加PAAS的堆肥产品;将PAAS堆肥产品与田土按堆肥施用比例混合后...研究添加聚丙烯酸钠(PAAS)对堆肥产品的吸水保水性能的影响.研究显示,PAAS能明显改善污泥结构;添加PAAS的堆肥产品吸水倍率可达到5.97 m L·g-1,吸水保水性能都优于未添加PAAS的堆肥产品;将PAAS堆肥产品与田土按堆肥施用比例混合后,其保水反应符合零级反应动力学规律,且模型计算结果与蒸发实验能较好吻合.展开更多
This paper aimed to improve the water-retention performance and basic physical properties of sulfoaluminate cement（SAC）-based planting cementitious material. The effect of natural zeolite on the performance of SAC-b...This paper aimed to improve the water-retention performance and basic physical properties of sulfoaluminate cement（SAC）-based planting cementitious material. The effect of natural zeolite on the performance of SAC-based planting material was investigated. The water-retention performance, porosity, compressive strength, and alkalinity had been tested and TG-DSC analysis had been adopted in this paper. Experimental results showed that zeolite was effective to improve the water-retention capacity and 10%, 20% and 30% natural zeolite increased the pore volume of the hardened pastes by 10.6%, 26.0%, and 38.6%, especially pore size below 0.1 μm was increased by 9.7%, 26.2% and 17.5%. And 10% zeolite was beneficial to the compressive strengths of cementitious material and 1, 3, and 28 d compressive strength reached up to 35.9, 55.0, 80.3 MPa. Furthermore zeolite decreased the alkalinity of pore fluid of hardened cementitious material, while the addition of zeolite reached up to 30%, the alkalinity of pore fluid of hardened cementitious material decreased by 8.9%. Therefore zeolite was suitable for improving the performance of SAC-based planting cementitious material.展开更多
Carboxyl methyl cellulose （CMC） was mixed into mortar to improve the waterretention performance of mortar, the quality of floated coat of aerated concrete became better. The consistency and compression strength of m...Carboxyl methyl cellulose （CMC） was mixed into mortar to improve the waterretention performance of mortar, the quality of floated coat of aerated concrete became better. The consistency and compression strength of mortar with CMC were studied. The water absorption was studied with the method of filter paper. The micro mechanism was researched with X-ray diffraction and scanning electron microscopy（SEM）. The experimental results show the water-holding performance of mortar with CMC is largely improved and it is better when the mixed amount is about 1.5%; the compression strength had a descending trend with the increase of CMC; CMC reacted with calcium hydroxide（CH） into the deposition of calcium carboxyl methyl cellulose.展开更多
This study investigates the evolution of the structural,volumetric and water retention behaviors of a compacted clay during soaking and desiccation considering the influences of freeze-thaw(FT)cycles and saline intrus...This study investigates the evolution of the structural,volumetric and water retention behaviors of a compacted clay during soaking and desiccation considering the influences of freeze-thaw(FT)cycles and saline intrusion.Compacted specimens were subjected to different FT cycles and then submerged in NaCl solution with different concentrations to facilitate the saline intrusion and measure the swelling behaviors.Shrinkage curve and filter paper tests were thereafter performed to reveal the clay’s volumetric and water-retention characteristics during desiccation.Mercury intrusion porosimetry and field emission scanning electron microscopy tests were conducted to observe the evolution of the clay’s microstructure.Experimental results show that the clay’s micropores decrease and macropores increase after FT cycles,which is associated with the migration of water,growth of ice crystals,and development of FT-induced cracks during FT cycles.Similar observations were obtained from specimens after the saline intrusion,which is attributed to the osmotic and osmotically-induced consolidation.FT-induced cracks significantly reduce the clay’s swelling and shrinkage potentials.FT cycles result in the shrinkage of micropores which leads to a reduction in the water retention capacity in the low suction range(capillary regime).The salinization suppresses the swelling of the clay and prolongs its primary and secondary swelling stages.The shrinkage potential initially increases and then decreases with increasing saline concentration.Salinization has significant influences on the osmotic suction and thus alters the clay’s water-retention curves in terms of total suction.It demonstrates little impact on the clay’s water-retention curves in terms of matric suction.展开更多
基金the National Natural Science Foundation of China (NSFC) (No40071044)the Deutsche Forschungsgemeinschaft (DFG) (NoZE 254/4)
文摘The spatial variations of the soil hydraulic properties were mainly considered in vertical direction. The objectives of this study were to measure water-retention curves, θ（ψ）, and unsaturated hydraulic conductivity functions, K（ψ）, of the soils sampled at different slope positions in three directions, namely, in vertical direction, along the slope and along the contour, and to determine the effects of sampling direction and slope position of two soil catenas. At the upper slope positions, the surface soils （0-10 cm） sampled in the vertical direction had a lower soil water content, 0, at a certain soil water potential （-1 500 kPa 〈 ψ 〈 -10 kPa） and had the greatest unsaturated hydraulic conductivity, K, at ψ 〉 -10 kPa. At the lower slope positions, K at ψ〉 -10 kPa was smaller in the vertical direction than in the direction along the slope. The deep soils （100 110 cm） had similar soil hydraulic properties in all the three directions. The anisotropic variations of the hydraulic properties of the surface soils were ascribed to the effects of natural wetting and drying cycles on the structural heterogeneity. These results suggested that the anisotropy of soil hydraulic properties might be significant in influencing soil water movement along the slope and need to be considered in modeling.
文摘研究添加聚丙烯酸钠(PAAS)对堆肥产品的吸水保水性能的影响.研究显示,PAAS能明显改善污泥结构;添加PAAS的堆肥产品吸水倍率可达到5.97 m L·g-1,吸水保水性能都优于未添加PAAS的堆肥产品;将PAAS堆肥产品与田土按堆肥施用比例混合后,其保水反应符合零级反应动力学规律,且模型计算结果与蒸发实验能较好吻合.
基金Funded by the National Natural Science Foundation of China(Nos.51302104,51472109)Science and Technology Development Plan of Shandong Province(No.2014G-ZX208001)the Program for Scientific Research Innovation Team in Colleges and Universities of Shandong Province
文摘This paper aimed to improve the water-retention performance and basic physical properties of sulfoaluminate cement（SAC）-based planting cementitious material. The effect of natural zeolite on the performance of SAC-based planting material was investigated. The water-retention performance, porosity, compressive strength, and alkalinity had been tested and TG-DSC analysis had been adopted in this paper. Experimental results showed that zeolite was effective to improve the water-retention capacity and 10%, 20% and 30% natural zeolite increased the pore volume of the hardened pastes by 10.6%, 26.0%, and 38.6%, especially pore size below 0.1 μm was increased by 9.7%, 26.2% and 17.5%. And 10% zeolite was beneficial to the compressive strengths of cementitious material and 1, 3, and 28 d compressive strength reached up to 35.9, 55.0, 80.3 MPa. Furthermore zeolite decreased the alkalinity of pore fluid of hardened cementitious material, while the addition of zeolite reached up to 30%, the alkalinity of pore fluid of hardened cementitious material decreased by 8.9%. Therefore zeolite was suitable for improving the performance of SAC-based planting cementitious material.
文摘Carboxyl methyl cellulose （CMC） was mixed into mortar to improve the waterretention performance of mortar, the quality of floated coat of aerated concrete became better. The consistency and compression strength of mortar with CMC were studied. The water absorption was studied with the method of filter paper. The micro mechanism was researched with X-ray diffraction and scanning electron microscopy（SEM）. The experimental results show the water-holding performance of mortar with CMC is largely improved and it is better when the mixed amount is about 1.5%; the compression strength had a descending trend with the increase of CMC; CMC reacted with calcium hydroxide（CH） into the deposition of calcium carboxyl methyl cellulose.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51779191 and 51809199)
文摘This study investigates the evolution of the structural,volumetric and water retention behaviors of a compacted clay during soaking and desiccation considering the influences of freeze-thaw(FT)cycles and saline intrusion.Compacted specimens were subjected to different FT cycles and then submerged in NaCl solution with different concentrations to facilitate the saline intrusion and measure the swelling behaviors.Shrinkage curve and filter paper tests were thereafter performed to reveal the clay’s volumetric and water-retention characteristics during desiccation.Mercury intrusion porosimetry and field emission scanning electron microscopy tests were conducted to observe the evolution of the clay’s microstructure.Experimental results show that the clay’s micropores decrease and macropores increase after FT cycles,which is associated with the migration of water,growth of ice crystals,and development of FT-induced cracks during FT cycles.Similar observations were obtained from specimens after the saline intrusion,which is attributed to the osmotic and osmotically-induced consolidation.FT-induced cracks significantly reduce the clay’s swelling and shrinkage potentials.FT cycles result in the shrinkage of micropores which leads to a reduction in the water retention capacity in the low suction range(capillary regime).The salinization suppresses the swelling of the clay and prolongs its primary and secondary swelling stages.The shrinkage potential initially increases and then decreases with increasing saline concentration.Salinization has significant influences on the osmotic suction and thus alters the clay’s water-retention curves in terms of total suction.It demonstrates little impact on the clay’s water-retention curves in terms of matric suction.
