Early shrinkage characteristics of high performance geopolymer concrete

In order to study the early shrinkage performance of high performance geopolymer concrete, a series of experimental research and analysis were carried out. The results show that the influence of silica fume content and water glass modulus on the early drying shrinkage of high performance geopolymer concrete is consistent within the range of test content, which decreases first and then increases. The influence of silica fume content and steel fiber content on the early autogenous shrinkage of high performance geopolymer concrete is consistent, which increases first and then decreases, and then increases. In the range of water glass modulus, the water glass modulus has a negative effect on the early autogenous shrinkage of high performance geopolymer concrete. Increasing the water glass modulus, the early autogenous shrinkage of high performance geopolymer concrete increases in turn. In the range of steel fiber content in the test, the steel fiber content has a positive effect on the early drying shrinkage of high performance geopolymer concrete. With the increase of steel fiber content, the early drying shrinkage of high performance geopolymer concrete decreases in turn. The early drying shrinkage of high performance geopolymer concrete specimens is between 1411×10⁻⁶-4387×10⁻⁶, and the early autogenous shrinkage is between 856×10⁻⁶-1188×10⁻⁶. With the increase of age, the drying shrinkage of high performance geopolymer concrete increases rapidly in the early stage, and the autogenous shrinkage decreases slightly first and then increases rapidly, and then gradually tends to be gentle. The early shrinkage curve can be divided into three stages (rapid growth stage, slow growth stage and stable stage). Based on the measured values of early drying shrinkage, the applicability of GL2000 model to the early drying shrinkage curve of high performance geopolymer concrete was verified.