Experimental Study on Mechanical Properties of Fly Ash Stabilized with Cement

Abstract

Cement-fly ash mixture has been commonly used for the foundation treatment projects in the fly ash stratum, as it is effective in improving foundation bearing capacity and reducing settlement of stratum. In order to figure out the effect of dynamic and static load on the mechanical properties exhibited by the cement-fly ash and the reaction mechanism of cement-fly ash, a combination of the unconfined compressive test, impact test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) method was adopted in this study to investigate the cement-fly ash test samples. As demonstrated by the results, the observed growth rate of 0–60 days (d) is higher than that in the later stages and the typical stress-strain curve can be divided into six sections under the unconfined compressive test. At the gas pressure of 0.2 MPa, the cement-fly ash samples exhibited obvious plastic properties in early curing time (0–60 d), and brittle failure was observed in the final stage (90 d). It is obvious that the value of dynamic compressive strength (DCS) is higher than that of unconfined compressive strength (UCS). The analysis of XRD has revealed that the hydration products are primarily derived from the hydration reaction of cement in the early stage and the pozzolanic reaction in the late stage. The pores of cement-fly ash are found to be filled with the hydration products, despite the presence of a mass of pores in the interior.

Improvement of Strength Parameters of Cement Matrix with the Addition of Siliceous Fly Ash by Using Nanometric C-S-H Seeds

“…Additionally, it is planned to assess the phase composition of the pastes using XRF and SEM-EDS methods. Analyses of this type would allow us to determine the degree of hydration of individual reaction products, which occur during the formation of the modified cement paste structure-e.g., [64].…”

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

“…However, although only a small amount of silica fume is needed to improve the strength of cement-stabilised soil, its cost is higher than that of cement. Furthermore, 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. This is difficult to apply in real-world engineering situations from the perspective of curing time.…”

Model Test of Bearing Characteristics of Fly Ash Foundation under Cyclic Loading

“…As a fundamental part of the CFMP composite foundation, changes in the model pile strength will cast an impact on the bearing capacity of the composite foundation. Therefore, according to the research results of the fly ash strength by Zhou et al [33,34], this was discovered after blending, according to 20% cement, 80% fly ash, and 35% water (Cement 42.5 general cement), which was poured into a customized PVC tube with a length of 50 cm, an inner diameter of 4 cm, and a wall thickness of 0.5 cm. The tube was placed in a curing room for 5 days, and then the PVC tube was cut with a miniature cutting machine.…”

“…In recent years, the research on the characteristics of soil-cement mixing piles have provided fresh insights into the treatment of fly ash foundation [10][11][12][13]. At present, many achievements have been made in the research on fly ash composite foundation under a static load at home and abroad [14][15][16].…”