The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cemen...The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cement, as well as the texture of dehydrated bodies of PVA, MC, and the potyblend solutions, were investigated with SEM. The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC. The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz. The key factor of forming the coherent interface is not the neutralization reaction between H + from hydrolysis of quarts: and OH- from hydration of cement, but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and onions from hydrolysis of quartz and hydration of cement, respectively. The model of the coherent interface formation is that excessive [HSiO3]- and [SiO3]2- onions are bonded with the hydrated cations such as Ca2+ and Al3+ , which is confirmed by the gel containing Ca and Si on the quartz surface.展开更多
The cement mixing (CM) pile is a common method of improving soft offshore ground. The strength growth of CM piles under complex conditions is affected by many factors, especially the cement and moisture contents, and ...The cement mixing (CM) pile is a common method of improving soft offshore ground. The strength growth of CM piles under complex conditions is affected by many factors, especially the cement and moisture contents, and shows significant uncertainty. To investigate the stochasticity of the early strength of CM piles and its impact on the displacement and stability of a seawall, a series of laboratory tests and numerical analyses were carried out in this study. Vane shear tests were conducted on the cement-solidified soil to determine the relationships between the undrained shear strength s_(u) of the cement soil curing in the seawater and the cement content a_(c), as well as the in situ soil moisture content w. It can be inferred that the 24 h undrained shear strength follows a normal distribution. A numerical model considering the random CM pile strength was established to investigate the deformation of the seawall. Due to the uncertainty of CM pile strength, the displacement of the seawall demonstrates a certain discreteness. The decrease of the mean undrained shear strength of CM piles causes a corresponding increase in the average displacement of the seawall. When the mean strength of CM piles is lower than a certain threshold, there is a risk of instability. Furthermore, the heterogeneity of the strength within an individual CM pile also has an impact on seawall displacement. Attention should be paid to the uncertainty of CM pile strength to control displacement and stability.展开更多
基金Funded by Natural Science Foundation of China (No. 49802004)
文摘The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cement, as well as the texture of dehydrated bodies of PVA, MC, and the potyblend solutions, were investigated with SEM. The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC. The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz. The key factor of forming the coherent interface is not the neutralization reaction between H + from hydrolysis of quarts: and OH- from hydration of cement, but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and onions from hydrolysis of quartz and hydration of cement, respectively. The model of the coherent interface formation is that excessive [HSiO3]- and [SiO3]2- onions are bonded with the hydrated cations such as Ca2+ and Al3+ , which is confirmed by the gel containing Ca and Si on the quartz surface.
基金supported by the Finance Science and Technology Project of Hainan Province(No.ZDKJ202019)the Key Research and Development Program of Zhejiang Province(No.2021C03014)the Natural Science Foundation of Zhejiang Province(No.LR22E080005),China.
文摘The cement mixing (CM) pile is a common method of improving soft offshore ground. The strength growth of CM piles under complex conditions is affected by many factors, especially the cement and moisture contents, and shows significant uncertainty. To investigate the stochasticity of the early strength of CM piles and its impact on the displacement and stability of a seawall, a series of laboratory tests and numerical analyses were carried out in this study. Vane shear tests were conducted on the cement-solidified soil to determine the relationships between the undrained shear strength s_(u) of the cement soil curing in the seawater and the cement content a_(c), as well as the in situ soil moisture content w. It can be inferred that the 24 h undrained shear strength follows a normal distribution. A numerical model considering the random CM pile strength was established to investigate the deformation of the seawall. Due to the uncertainty of CM pile strength, the displacement of the seawall demonstrates a certain discreteness. The decrease of the mean undrained shear strength of CM piles causes a corresponding increase in the average displacement of the seawall. When the mean strength of CM piles is lower than a certain threshold, there is a risk of instability. Furthermore, the heterogeneity of the strength within an individual CM pile also has an impact on seawall displacement. Attention should be paid to the uncertainty of CM pile strength to control displacement and stability.
