Effect of Calcium Carbonate on the Mechanical Properties and Microstructure of Red Clay

Lijie Chen,Pengyan Bi,Xin Yang,Xiang Huang,Xuejun Chen,Xiang Ding,He Wang

doi:10.1155/2020/5298186

Lijie Chen, Pengyan Bi + Show 5 more

Open Access

https://doi.org/10.1155/2020/5298186

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Abstract

The influence of precipitated calcium carbonate on the strength and microstructure of red clay was studied. Precipitated calcium carbonate was added to red clay at ratios of 0%, 5%, 10%, 15%, and 20%. Shear tests were carried out on the samples to observe the effect of calcium carbonate on the mechanical properties of red clay. The results showed that, with increasing calcium carbonate content, the strength of red clay first decreased and then increased. The maximum strength was obtained for the sample with 20% calcium carbonate. Scanning electron microscopy (SEM) was used to observe the changes in microstructure caused by addition of calcium carbonate. The pores and cracks analysis system (PCAS) was used to quantitatively characterize the microstructure changes detected in SEM images. The addition of calcium carbonate decreased the pore area and increased the total number of pores of red clay. The incorporation of calcium carbonate caused the red clay particles to agglomerate. The higher the calcium carbonate content, the stronger the agglomeration of red clay particles in the soil samples.

Highlights

Red clay is widely distributed in areas south of the Changjiang River in China, such as Guangxi, Guizhou, and Yunnan
Scanning electron microscopy (SEM) observation, particle size analysis, and stacking measurements are carried out to study the effect of precipitated calcium carbonate content on the microstructure of red clay
pores and cracks analysis system (PCAS) software developed by Liu et al [16], which is a commercial software for analyzing the pore structure of soil in highresolution SEM images, was used to analyze the calcium carbonate-doped red clay samples

Summary

Introduction

Red clay is widely distributed in areas south of the Changjiang River in China, such as Guangxi, Guizhou, and Yunnan. The production of ordinary Portland cement has considerable environmental effects because it is an energy-intensive industrial process, accounting for 5%–7% of global CO2 emission [5] Many innovative approaches, such as liquid stabilizers [3, 6], have been used to improve the properties of red clay. Tovey and coworkers [11, 12] conducted a quantitative analysis of electron micrographs of soil structures and combined several image processing and analysis techniques to study the porosity of clay particles. SEM observation, particle size analysis, and stacking measurements are carried out to study the effect of precipitated calcium carbonate content on the microstructure of red clay. PCAS software is used to quantitatively analyze the influence of calcium carbonate incorporation on the porosity, micropore structure, and particle size distribution of red clay

Materials and Methods

Results and Discussion

Pore Structure Analysis of Calcium Carbonate-Doped Red Clay

Influence of Calcium Carbonate Doping on the Grain Size