Synthesis of ternary binders and sand-binder ratio on the mechanical and microstructural properties of geopolymer foamed concrete

Abstract

The development of sustainable construction building materials with a lower environmental impact throughout both the manufacturing and operation phases of the material lifecycle is capturing the attention of the global housing and construction sectors. Recent advancements have resulted in the development of geopolymer foam concrete, which combines the performance and energy savings associated with lightweight foam concrete with the cradle-to-grave emissions reductions associated with the use of a geopolymer binder composed of supplementary cementitious materials (by-products). The purpose of this study is to determine the influence of sand to binder ratio and by-product materials, fly ash, ground granulated blast furnace slag, palm oil fuel ash, palm oil clinker powder and bottom ash on structural grade geopolymer foamed concrete with a density of 1700 kg/m3. The mechanical properties such as compressive strength, splitting tensile strength, rupture modules, and static and dynamic modules of elasticity were investigated; microstructure investigations using X-ray Diffraction (XRD) and Field-Emission Scanning Electron Microscope (FESEM) were also reported. The results show that geopolymer foamed concrete (GFC) with a structural grade concrete of compressive strengths ranging from 27 to 39 MPa could be produced. The use of fine sand improved the geopolymer foamed concrete's mechanical and microstructural characteristics. The tensile strength, modulus of rupture, and elasticity modulus were found in the ranges of 0.9 – 2.53 MPa, 1.35 – 4.28 MPa, and 3.54 – 6.86 GPa, respectively. The non-uniform distribution of the voids of ternary composites geopolymer foamed concrete and the formation of calcium aluminosilicate hydrates C-(N-) A-S-H gel are found.