Optimization of fresh properties, rheological parameters and mechanical performances of grouts containing bentonite

Abstract

Grouting is widely utilized in construction, offering numerous applications such as concrete repairs and soil stabilisation. However, the workability and strength of grout heavily depend on the water-to-binder (w/b) ratio, which can present certain challenges since a suitable grout should fulfil the requirements of the intended application. As substitutes for Portland cement in various applications, pozzolanic materials such as Bentonite offer numerous benefits including reduced environmental impact and providing chemical resistance. This study aims to investigate the optimum content of the main factors affecting the properties of the grout; bentonite replacement level (BT), superplasticiser dosage (SP) and w/b ratio using factorial design. A full factorial design was carried out to mathematically model the spread, flowability, cohesion, rheological parameters and compressive strength of grouts containing BT. Prediction models were developed to describe the effect of the different proportions. The developed models can be used further to optimise the proportions of the grout. The w/b ratio varied between 0.36 and 0.58, while the bentonite content and SP dosage were in the range of 0–6% and 0–0.8%, respectively. Results show that the spread of grout increased with increasing the SP dosage and w/b ratio and decreased with increasing BT content. Conversely, cohesion decreased with increasing the SP dosage and w/b ratio and increased with increasing BT content. The yield stress of the grout was influenced by the dosage of BT, SP and W/B. Increasing BT had approximately 2.2- and 1.42-times greater influence than increasing W/B and SP respectively. The plastic viscosity was affected, in order of significance, by the dosage of BT, SP and W/B. BT led to improvement of grout strength, while w/b ratio decreased the strength. Interactive effects of the parameters on the measured properties were also observed.