Compression, Unloading-reloading, and tension mechanical behaviors of Silt-based foamed concrete under uniaxial loading

Abstract

• The strength and deformation characteristics under uniaxial loading were researched in detail. • The relationship between uniaxial compression, unloading–reloading, and tension conditions was established. • Micro-structure and XRD results under different silt contents were displayed. The present study describes the comprehensive mechanical properties of silt-based foamed concrete under uniaxial loading conditions and the effect of wet density and silt content on mechanical performance. The uniaxial compression, unloading–reloading, and tension experiments were conducted to examine the strength and deformation characteristics, along with the failure mechanism, under different loading conditions. The test results indicated that, under uniaxial compression loading, the stress–strain curves present obvious elastoplastic characteristics, featuring four stages. A damage constitutive model with a fitting degree of 0.95 was employed to describe the overall compression stress–strain relationship. Under the uniaxial unloading–reloading condition, the unloading–reloading process did not produce extra plastic strain, nor did it change its original compression path. Foamed concretes possessed well resilient ability even at a large strain of 9%. The resilient modulus may be considered as basically constant with the increasing strain, and was on average 41.1% greater than the compressive modulus. Under uniaxial tension loading, the stress increased linearly with strain until peak value and then decrease rapidly to 0. Additionally, density contributed greatly to the formation of the strength, yet silt content diversely affected the strength parameters of foamed concrete. The primary reason for this is that the addition of silt transformed the pore structures from uniformly distributed sphericity into irregular combined bubbles with larger diameters, thereby decreasing the strength of the foamed concrete.