Influence of SCMs on Flow Properties of Self-compacting Mortar Made with Recycled Fine Aggregate

Abstract

The economic growth in India has led to the unprecedented infrastructure development, and as a result, the consumption of raw materials for the construction industry has grown at a very fast pace. Thus, they account for the significant contribution toward greenhouse emissions. In the current global scenario, the faster construction process has become the only mandate to fulfill the demand for infrastructure. However, the construction industry must follow the sustainability paramount to manage its environmental impact. Hence, this study has aimed to address these concerns by using recycled materials such as fly ash (FA), silica fume(SF), and recycled fine aggregate (RFA). The main aim of this paper is to investigate the effect of supplementary cementitious materials (SCMs) with recycled fine aggregate on the flow/rheological properties of fresh self-compacting mortar. Self-compacting mortar is made with cement and fine aggregate in which the cement was replaced with various proportions of FA and SF and the natural fine aggregate with RFA. The mortar mix composition has been finalized as per EFNARC guidelines. A total of twenty mixes is prepared by using different proportions of mineral admixtures and different types of sand for this experimental investigation. The flow properties of mortar are assessed in terms of slump flow through flow cone and in terms of V-funnel efflux time through V-funnel test. The flow tests are performed at varying water/powder (w/p) ratio and varying the dosage of superplasticizer (SP). The cube specimens of mortar are also tested at various ages to determine the strength. The influence of RFA on the flow properties of mortar was observed. It is noted that mortar made with RFA has shown a gradual decrease in the flowability due to its high water absorption and it demanded more SP dosage to maintain the flowability. For a better understanding of the effect of morphology of SCMs on the flow properties, the mortar flow properties were investigated with binary and ternary combination of SCMs. From the result, it is observed that the self-compacting mortar can be prepared with RFA at ternary combination of binder (cement + SCMs) to achieve the desired flow characteristics at its 100% replacement level.