Drying shrinkage and creep performance of geopolymer concrete

The creep behavior and drying shrinkage performance of fly ash geopolymer (GP) concrete mixtures have been investigated using equivalent grade 40-MPa ordinary Portland cement (OPC) concrete as the reference system. Drying shrinkage values, measured in accordance with AS 1012.13-1992, up to one year fell well below the nominal 700 μstrain limit, with GP concrete values typically less than 400 μstrain at 1 year. Variations in basic mean creep coefficient of concrete (Фcc.b), measured as the ratio of the creep strain to elastic strain for a specimen loaded at 28 days under constant stress of 0.4f c (f c – 28 day compressive strength) was monitored for up to 52 weeks. Values of Фcc.b obtained for steam-cured GP concrete was found to be of the order of 45% lower than corresponding OPC concrete. Based on these results, the effects of GP concrete mixtures on load-dependent (creep) deformations appear to be negligible. The paper further discusses factors that contribute to observed GP concrete creep deformation and drying shrinkage performance.