Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer

Chenglong Yin,Wei Zhang,Xunli Jiang,Zhiyi Huang

doi:10.3390/ma11101933

Abstract

Initial water content significantly affects the efficiency of soil stabilization. In this study, the effects of initial water content on the compressibility, strength, microstructure, and composition of a lean clay soil stabilized by compound calcium-based stabilizer were investigated by static compaction test, unconfined compression test, optical microscope observations, environment scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results indicate that as the initial water content increases in the range studied, both the compaction energy and the maximum compaction force decrease linearly and there are less soil aggregates or agglomerations, and a smaller proportion of large pores in the compacted mixture structure. In addition, for specimens cured with or without external water supply and under different compaction degrees, the variation law of the unconfined compressive strength with initial water content is different and the highest strength value is obtained at various initial water contents. With the increase of initial water content, the percentage of the oxygen element tends to increase in the reaction products of the calcium-based stabilizer, whereas the primary mineral composition of the soil-stabilizer mixture did not change notably.

Highlights

From a historical perspective, clayey soil, derived from the rock weathering process of the geological cycle [1,2], already existed long before humankind
The results show that as the increases, the number of large aggregates agglomerations reduces while show that as the increases, the number of large and agglomerations reduces show that as the initial water content (IWC) increases, the number of large aggregates and agglomerations reduces while while the quantity of individual particles increases; and the number of large inter-aggregate pores the quantity of individual particles in turn the number of large inter-aggregate pores the quantity of individual particles increases; and in turn the number of large inter-aggregate pores decreases, leading to the soil structure becoming decreases, 15a–d)
The results of optical microscope observation identify the foundational effect of the molding water: it breaks down the soil aggregates and agglomerations into individual particles and makes the water: it breaks down the soil aggregates and agglomerations into individual particles and makes the soil structure more able to be changed

Summary

Introduction

Clayey soil, derived from the rock weathering process of the geological cycle [1,2], already existed long before humankind. In order to control or constrain the deflections and movement of clayey soils and enhance its compressibility, strength, stiffness, the resistance to water and cracking, and other engineering properties, a variety of inorganic, organic, and biological materials such as lime [8,9,10,11], Portland cement [12,13,14,15], fly ash [16,17], granulated blast furnace slag [18,19,20], cement kiln dust [21,22], rice husk ash [23,24], polyacrylamide copolymers [25,26], bioenergy coproduct [27,28], and so on, in the form of powder or liquid, was mixed with this problematic material with or without extra water before compaction. Soil stabilization is a traditional but cost-effective technique in civil engineering, and finds its prevailing applications in pavement base, subbase, or embankment, canal or reservoir lining, shallow building foundations, and stabilized rammed earth constructions among others, especially for locations where relatively high-cost materials such as gravel and crushed stone are unavailable or have a long transportation distance while the budget of the construction project is probably limited [7,29,30].

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