Abstract
Foam concrete is a low-density controlled strength material that can potentially be used for accommodating different types of particles—recycled fine aggregate being an example. The paste matrix of this material has a cellular microstructure, and bulk performance is readily affected by the inclusion of fines. To study the effect of inclusion of fines on mechanical performance and foam structure of foam concrete, a group of 0.55 g/cm3 foam–sand composite mixtures with high-volume fly ash replacement are investigated. The elastic modulus is measured by a vibrational frequency test. The crushing mechanics are determined by the load-displacement response from a penetration test. The effect of particle inclusion on the foam concrete microstructure is characterized using micro computed tomography. The results indicate that use of fine-graded sand particles at a small dosage simultaneously reduces cement content and enhances the crushing performance, however poor material performance is observed for a high sand content. The cellular structure of the foam–sand composite, and thus its mechanical behavior, can be substantially diminished by larger sand particles, especially when the particle size is larger than the voids in foam.
Highlights
Concrete sustainability has emerged as a key theme across modern concrete studies because of the large environmental impact of cement production [1] and natural aggregate exploitation [2].All three Rs of environmental protection—reduce, reuse, recycle—can be applied in some ways to concrete infrastructure
This study focuses on investigating the effect of adding fine particles to the foam concrete crushing behavior and void structure, where the mixture is considered as a foam–particle composite
Continuous increase of the elastic modulus was seen for all samples from 7 to 21 days, where the average increase was 7.8% at 14 days and only 2.6% at 21 days
Summary
Concrete sustainability has emerged as a key theme across modern concrete studies because of the large environmental impact of cement production [1] and natural aggregate exploitation [2]. The use of fine aggregates is seen in some foam concrete studies, most of the investigated foam mixtures are denser than 0.8 g/cm3 [12,18,19] and only a few studies focused on the influence of adding sand into low-density foamed paste [2,20,21]. Based on the existing literature, the strength of low-density foam concrete mixtures is sensitive to the inclusion of particles and can be affected by the filler type. Given the promise of using recycled fines in ultra-lightweight foam concrete for low strength applications, low-density foam mixture design and processing deserve greater attention by researchers. This study focuses on investigating the effect of adding fine particles to the foam concrete crushing behavior and void structure, where the mixture is considered as a foam–particle composite. In order to clarify the influence of sand inclusion on the foam structure, micro computed tomography (micro-CT) was further used to characterize the 3D morphology of a subgroup of the samples
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