The Effect of Circulating Fluidised Bed Bottom Ash Content on the Mechanical Properties and Drying Shrinkage of Cement-Stabilised Soil.

Yuanlong Wang,Yongqi Zhao,Min Zhou,Yunshan Han

doi:10.3390/ma15010014

Abstract

This study aimed to determine the effect of circulating fluidised bed bottom ash (CFB-BA) content on the mechanical properties and drying shrinkage of cement-stabilised soil. Experiments were performed to study the changes in unconfined compressive strength and expansibility of cement-stabilised soil with different CFB-BA contents and the underlying mechanisms based on microscopic properties. The results show that CFB-BA can effectively increase the unconfined compressive strength of the specimen and reduce the amount of cement in the soil. When the combined content of CFB-BA and cement in the soil was 30%, the unconfined compressive strength of the specimen with C/CFB = 2 after 60 days of curing was 10.138 MPa, which is 1.4 times that of the pure cement specimen. However, the CFB-BA does not significantly improve the strength of the soil and cannot be added alone as a cementing material to the soil. Additionally, swelling tests showed that the addition of CFB-BA to cement-stabilised soil can significantly reduce the drying shrinkage. This research project provides reference values for the application of CFB-BA in cement–soil mixing piles, including compressive strength and the reduction in the shrinkage deformation of specimens.

Highlights

In construction, some types of soil pose a greater challenge to the project due to their poor engineering performance
Through unconfined compressiveratios strength (UCS) tests, swelling tests, and microscopic analysis, this project studied the influence of circulating fluidised bed bottom ash (CFB-BA) on the mechanical properties and shrinkage characteristics of cement-stabilised soil and obtained the following conclusions:
According to the unconfined compressive strength test, the increase in cement content in soil from 25% to 30% resulted in only a small increase in strength, the optimum cement content in soil is 25%

Summary

Introduction

Some types of soil pose a greater challenge to the project due to their poor engineering performance. Adding fly ash [2] and coal-measure metakaolin [3] can improve the late strength of cement-stabilised soil, but this has little effect on the early strength. Fei Xu [9] studied the modification of cement-stabilised soil using polynaphthalene sulfonate (NS) and reported that it can promote the hydration of cement and weaken the adsorption between soil minerals and water molecules, making NS preferentially adsorb soil minerals The former can delay the formation of AFt (ettringite) and AFm (monosulfate) to compensate for the volume shrinkage of the specimens and increase the strength, and the latter can increase the drying shrinkage of the specimens.

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Discussion

Conclusion