Constitutive Model of Uniaxial Compressive Behavior for Roller-Compacted Concrete Using Coal Bottom Ash Entirely as Fine Aggregate

Coal bottom ash (CBA) is one of the by-products that can be employed as fine aggregate to replace natural sand in concrete. Owing to the very low water demand, roller-compacted concrete (RCC) has the potential to use CBA as fine aggregate at a high proportion. However, little research about RCC using CBA entirely as fine aggregate has been conducted. In this study, the uniaxial compressive strength, deformation, stress–strain curves, and splitting tensile strength of CBA-containing RCC (CBA RCC) were studied to bridge this gap. The compressive strength, elasticity modulus, and splitting tensile strength of all mixtures decreased with increasing CBA content. The relationship between compressive strength and splitting tensile strength of CBA RCC was proposed, which is very close to that recommended by the CEB-FIP code. The uniaxial compressive constitutive model based on the continuum damage theory can well illustrate the stress–strain relationship of CBA RCC. The growth process of damage variable demonstrates the hybrid effect of coarse aggregate, cement, and compacting load on delaying damage under uniaxial compression. The theoretical formula can also accurately illustrate the stress–strain curves of RCC presented in the literature studies.

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