Low-Carbon Foamed Concrete Based on Alkali Residue and GGBS versus Conventional Foamed Concrete: Comparative Experimental Research

Abstract

This study advocates a low-carbon foamed concrete (FC), termed alkali residue (AR) ground granulated blast furnace slag (GGBS)-based FC (AG-FC). A comprehensive assessment of the macro-micro properties of AG-FC and conventional FC (C-FC) was performed through a series of tests, including a compression test, triaxial test, dry–wet cycle test, freeze–thaw cycle test, scanning electron microscope examination, X-ray diffraction analysis, and thermogravimetric analysis. The findings reveal that AG-FC exhibits excellent mechanical performance, with a 28-day compressive strength exceeding 1.0 MPa. AG-FC is primarily composed of CaCO3, C─ S─ H, Ca(OH)2, and Friedel’s salt (Fs), whereas C-FC is dominated by C─ S─ H, Ca(OH)2, and CaCO3. AG-FC exhibits excellent durability, with a durability coefficient of 0.798–0.87. During dry–wet cycles, the deterioration primarily arises from pore water pressure, pore gas pressure, and temperature stress. During freeze–thaw cycles, the deterioration effects stem from the pore water pressure and frost heaving force. AG-FC exhibits a noteworthy capability to significantly reduce CO2 emissions, accounting for approximately 35%–40% of the emissions produced by C-FC. AG-FC exhibits noteworthy attributes, including cost-effectiveness, low carbon emissions, environmental friendliness, superior mechanical performance, and exceptional durability, making it highly promising for a wide range of applications.