An investigation of the durability of ultra-lightweight high-strength geopolymeric composites

Abstract

As promising and sustainable construction materials, ultra-lightweight high-strength geopolymeric composites (ULHSGCs) may be exposed to harsh corrosive environments. This study is designed to examine the durability of a new ULHSGC with a compressive strength ≥70 MPa and a density ≤1500 kg/m3. In preparing the ULHSGC, ground granulated blast furnace slag (GGBS) and silica fume (SF) were used as the binder, and fly ash cenospheres (FACs) and hollow glass microspheres (HGMs) were used as aggregates. A series of measurements, including accelerated carbonation, rapid chloride migration (RCM), sulfate resistance, X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP) tests, was conducted to determine the effects of the SF content, Na2O content, SiO2/Na2O ratio and fibre type on the durability of the ULHSGC. The results indicated that the proposed ULHSGC with 10–15 % SF content and 6–7% Na2O content exhibited excellent compressive strength, resistance to carbonation, and resistance to chlorine penetration as well as suitable resistance to sulfate attack. Versions of the ULHSGC with lower SiO2/Na2O ratios had better compressive strengths, resistances to chloride penetration and resistances to sulfate attack but lower resistance to carbonation. The addition of polypropylene (PP) fibres and polyethylene (PE) fibres increased the porosity, which reduced the durability of the ULHSGC. However, given the significant contribution of the fibres to the compressive strength, the negative effect of adding 0.5 vol% fibres on the durability was acceptable.