Effects of Pozzolans and Nano Bentonite on Properties of Grout

Cement grouts have extensive use in the repairing of cracks in structural and non-structural concrete and masonry, soil stabilization, etc. but for some applications, they need some modification in properties. Laboratory studies on the properties of cement grouts and the modification of these properties can pave the way for the greater use of these materials in applications such as the sealing of leachates of dangerous wastes buried at low depths, filling cracks in concrete bodies, etc. This study investigated the effect of silica fume, nano silica, nano bentonite, and superplasticizer on the physical and chemical properties of cement grout. For this purpose, 36 mixed designs in two separate groups for silica fume and nano silica were created. Then, the properties of fresh and hardened grout including flowability, bleeding, and 7, 28, and 90-day compressive strength were measured. The results showed that while nano bentonite and nano silica are effective in reducing bleeding, silica fume has a greater effect on this phenomenon. The greatest strength improvement was observed in the design containing silica fume and nano bentonite (CSB). While nano bentonite alone does not significantly improve the compressive strength of the grout, its combination with silica fume and nano silica has a notable positive impact on the compressive strength and bleeding of this mixture.