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Rice husk ash (RHA) has been considered as a suitable cement mineral additive. A key issue in the study of RHA blended cement is to evaluate the contribution of RHA to hydration kinetics. Although numerous methods have been given to assess the hydration degree of blended cement, there are still some controversial aspects, such as the effect of temperature is not well considered. Therefore, this study aims at developing a method for evaluating the hydration degree of blended cement which can consider the influence of temperature. The key of this method is to adopt a hydration kinetic model of nonevaporable water (NEW) to determine the ultimate NEW content of blended cement when it is completely hydrated. In the hydration kinetic model, the Arrhenius equation is introduced to reflect the relationship between hydration rate and temperature, and the inversion phenomenon between ultimate NEW and temperature is considered simultaneously. Furthermore, the hydration process of portland cement pastes containing RHA (two types of RHA: RHA-1 from the factory and RHA-2 by controlled combustion) is analyzed by this assessment method. It is found that the effect of temperature on RHA cement is similar to that of ordinary Portland cement (OPC), which has an inversion phenomenon between hydration degree and temperature. Under the same temperature, the hydration degree of RHA cements is lower than that of OPC, while the difference in hydration degree gradually decreases with the progress of hydration. Moreover, according to the fitting results of the model when m = 3, the addition of RHA could reduce the apparent activation energy (Ea) of blended cement, the Ea values of OPC, RHA-1 cement and RHA-2 cement are 37.64 kJ/mol, 35.39 kJ/mol and 34.18 kJ/mol, respectively.
Xue Luo; Xunli Jiang; Qi Chen; Zhiyi Huang. An assessment method of hydration degree of Rice husk ash blended cement considering temperature effect. Construction and Building Materials 2021, 304, 124534 .
AMA StyleXue Luo, Xunli Jiang, Qi Chen, Zhiyi Huang. An assessment method of hydration degree of Rice husk ash blended cement considering temperature effect. Construction and Building Materials. 2021; 304 ():124534.
Chicago/Turabian StyleXue Luo; Xunli Jiang; Qi Chen; Zhiyi Huang. 2021. "An assessment method of hydration degree of Rice husk ash blended cement considering temperature effect." Construction and Building Materials 304, no. : 124534.
Soft soils are usually treated to mitigate their engineering problems, such as excessive deformation, and stabilization is one of most popular treatments. Although there are many creep models to characterize the deformation behaviors of soil, there still exist demands for a balance between model accuracy and practical application. Therefore, this paper aims at developing a Mechanistic-Empirical creep model (MEC) for unsaturated soft and stabilized soils. The model considers the stress dependence and incorporates moisture sensitivity using matric suction and shear strength parameters. This formulation is intended to predict the soil creep deformation under arbitrary water content and arbitrary stress conditions. The results show that the MEC model is in good agreement with the experimental data with very high R-squared values. In addition, the model is compared with the other classical creep models for unsaturated soils. While the classical creep models require a different set of parameters when the water content is changed, the MEC model only needs one set of parameters for different stress levels and moisture conditions, which provides significant facilitation for implementation. Finally, a finite element simulation analysis of subgrade soil foundation is performed for different loading levels and moisture conditions. The MEC model is utilized to predict the creep behavior of subgrade soils. Under the same load and moisture level, the deformation of soft soil is largest, followed by lime soil and RHA–lime-stabilized soil, respectively.
Xunli Jiang; Zhiyi Huang; Xue Luo. An Improved Mechanistic-Empirical Creep Model for Unsaturated Soft and Stabilized Soils. Materials 2021, 14, 4146 .
AMA StyleXunli Jiang, Zhiyi Huang, Xue Luo. An Improved Mechanistic-Empirical Creep Model for Unsaturated Soft and Stabilized Soils. Materials. 2021; 14 (15):4146.
Chicago/Turabian StyleXunli Jiang; Zhiyi Huang; Xue Luo. 2021. "An Improved Mechanistic-Empirical Creep Model for Unsaturated Soft and Stabilized Soils." Materials 14, no. 15: 4146.
With increased awareness of environmental protection, the output of traditional curing agents such as cement and lime is less and less, so it is urgent to develop new curing agents with high efficiency and environmental benefits. Thus, this study aims at investigating the application of rice husk ash (RHA) from agricultural waste to the soft soil stabilization. A series of tests are conducted to analyze the strength development process and soil–water characteristics of rice husk ash–lime (RHA–lime) stabilized soils. The results of the strength tests showed that by increasing the content of RHA, the unconfined compressive strength (UCS) and splitting strength of stabilized soils increased first and then decreased. The effective shear strength indexes of the three soil types (soft soil, lime-stabilized soil, and RHA–lime soil) are measured and compared. It is found that RHA can effectively improve the shear resistance and water resistance of stabilized soil. The results of methylene blue test demonstrated that RHA can also promote the reduction of the specific surface area and swelling potential energy of lime-stabilized soil. In addition, the influence of RHA on mineral composition and morphology change in stabilized soils is studied at the microscopic level. The X-ray diffraction tests and scanning electron microscope (SEM) tests showed that strength development and change of soil–water properties of RHA–lime stabilized soil are attributed to enhanced cohesion by cementation and pores filling with agglomerated mineral.
Xunli Jiang; Zhiyi Huang; Fuquan Ma; Xue Luo; Ma; Luo. Analysis of Strength Development and Soil–Water Characteristics of Rice Husk Ash–Lime Stabilized Soft Soil. Materials 2019, 12, 3873 .
AMA StyleXunli Jiang, Zhiyi Huang, Fuquan Ma, Xue Luo, Ma, Luo. Analysis of Strength Development and Soil–Water Characteristics of Rice Husk Ash–Lime Stabilized Soft Soil. Materials. 2019; 12 (23):3873.
Chicago/Turabian StyleXunli Jiang; Zhiyi Huang; Fuquan Ma; Xue Luo; Ma; Luo. 2019. "Analysis of Strength Development and Soil–Water Characteristics of Rice Husk Ash–Lime Stabilized Soft Soil." Materials 12, no. 23: 3873.