Contribution to cemented body strength by crushed stone with different particle sizes and contents: insights from PFC3D simulations

Abstract

The cemented body formed by cement-based materials and crushed stone after cementing is a brittle material, and the content and particle sizes of the crushed stone cause the specimens to show different damage patterns. In order to quantitatively study the effect of crushed stone content and particle sizes on the strength of cemented bodies, in this paper, crushed stone cemented body (CSCB) were prepared using crushed stone (CS), aluminate cement (AC), fly ash (FA), alkali-activated. The real shape of crushed stone was obtained and the numerical model was constructed using 3D scanning modeling, the fine-scale parameters of the PFC numerical model were calibrated and calibrated according to the experimentally measured stress–strain curves, and a series of specimens were constructed for crushed stone content and crushed stone particle sizes. The uniaxial compressive strength, crack extension and distribution pattern, high and low stress force chain distribution, and contact force fabric characteristics of specimens with different crushed stone content and crushed stone particle sizes under the same axial loading conditions were investigated. The results show that (1) the strength of the specimen and the total number of cracks produced by the specimen show a negative correlation, the distribution of internal cracks in the specimen with high strength is concentrated and dominated by one main crack with a lower total number of cracks, and the number of cracks in the specimen with low strength is higher and the distribution is dispersed. The development and expansion of cracks is the main reason for the final destruction of the cemented body. (2) The internal contact forces are redistributed after the specimen is loaded, and the number of high stress force chains accounted for determines the compressive strength of the specimen. With the increase in crushed stone content, the strength shows a first increase and then decrease. (3) Crushed stone content in the range of 50–60% contributes the most to the strength of the specimen. The effect of crushed stone particle sizes on the strength is more complicated, the strength of crushed stone cemented body of 3–5 mm and 5–7 mm particle sizes is larger, and the effect of contact between cement and crushed stone is good, and the effect of internal cement and crushed stone cementation is poor in the specimens with particle sizes of 6–8 mm and 7–9 mm.