Characteristics of Fresh and Hardened Sustainable Foamed Concrete for Structural Applications

In light of the trends towards producing sustainable lightweight concrete and utilizing local resources and recycled materials, this study explored these possibilities. Foamed concrete is considered ecofriendly because of its lightweight, excellent thermal and acoustic insulation properties, and low environmental impact. Most previous research focused on the properties of foam concrete, whose compressive strength does not exceed 10–15 MPa and is used for nonstructural purposes. However, through this work, foam concrete mixtures were produced with a compressive strength of about 23 MPa, which opens the way for their application in structural members. In this work, foamed concrete was produced to examine the possibility of meeting structural and sustainability requirements with foamed concrete. The properties of this produced concrete were investigated through four sets of tests: tests in the fresh state, including a flow test; tests related to the durability of concrete, or what is called permeation properties, including water absorption, sorptivity, and porosity tests; tests for hardened concrete related to strength, including compressive and indirect tensile tests; and finally, a microstructure test, including a scanning electron microscopy (SEM) test. As a means of improving strength and reducing the use of cement, cement was partially replaced with waste glass powder (WGP), and fly ash was used as cementing material, in addition to the use of superplasticizer and silica sand to produce concrete foam with structural strength. The fresh mix densities all fell within the range for lightweight concrete. The 28‐day compressive strength of the mix with the superplasticizer and WGP was moderate, approximately 37.6% greater than that of the control mix, and that of the mix with the superplasticizer alone was approximately 35.9% greater. WGP had a marginal effect on compressive strength. Adding superplasticizer alone reduced the porosity and sorptivity by 32.3% and 63.9%, respectively. Adding WGP alone or with a superplasticizer reduced porosity and sorptivity, but the differences remained insignificant relative to the mix without any additions. The superplasticizer reduced water absorption by approximately 35.9% compared to WGP alone, which only slightly reduced water absorption, or with WGP and the superplasticizer together. The superplasticizer increased the 28‐day tensile and flexural strengths by up to 40.5% and 32.1%, respectively, relative to the control mix. Silica sand proved to be a good alternative to normal sand in foamed concrete mixes. For all mixes, the foamed concrete produced exhibited a foamed structure with numerous pores.