Effect of Fuller-fine sand on rheological, drying shrinkage, and microstructural properties of metakaolin-based geopolymer grouting materials

While metakaolin (MK)-based geopolymer grouting materials (MGGMs) are new type of grouting materials, the poor rheological properties and high drying shrinkage hinder their practical applications. In this work, Fuller-fine sand powders (Fuller-FS) (10, 20, 30 and 40 wt%) were used as a fine inorganic admixture to investigate effects of this addition on the rheological properties, drying shrinkage and mechanical strength of MGGMs. The results indicated that pure MGGMs or MGGMs containing Fuller-FS were more consistent with the Herschel-Bulkley rheological model. Incorporating Fuller-FS into MGGMs can improve their rheological and compressive strength properties, and reduce their drying shrinkage. The initial shear stress value of geopolymer with Fuller-FS was 80% lower or more than that of pure metakaolin-based geopolymer at a constant shear rate (100 s−1), and the MGGM containing 30 wt% Fuller-FS presented satisfactory yield stress (about 1 Pa). The replacement of different content of metakaolin by Fuller-FS improved particles packing and compactness of MGGMs, thus resulting in lower 91-day drying shrinkage ( by 65 %), and higher 28-day compressive strength ( by 35 %) (curing at 20 °C and 50 ± 10% RH).