Effect of nano-clay on workability, mechanical, and durability properties of self-consolidating concrete containing mineral admixtures

Abstract

The effects of nano-clay (NC) addition on fresh state, mechanical, and durability properties of plain and blended cement self-consolidating concrete (SCC) incorporating mineral admixtures as supplementary cementitious materials were investigated. Mineral admixtures such as silica fume (SF), class F fly ash (FA), rice husk ash (RHA), and ground granulated blast furnace slag (GGBFS) were used as partial replacement of cement. Initially, SCC mixes with 1%, 2%, and 3% NC as cement replacement, by weight, were prepared and the workability properties (i.e. slump flow, T50 and V-funnel flow time, and passing ability ratio via L-box test), the mechanical properties (i.e. compressive strength, splitting tensile strength, the modulus of elasticity and the ultrasonic pulse velocity), and the durability properties (i.e. water absorption, water penetration depth via water permeability test, electrical resistivity, chloride migration coefficient and the time-dependent corrosion current variation via impressed voltage test) were determined for evaluating the effectiveness of NC inclusion on characteristics of SCC. According to the results, the addition of NC to plain SCC satisfied all the required specifications for SCC as per EFNARC (European Federation for Specialist Construction Chemicals and Concrete Systems). While the addition of 3% NC by weight of cement improved the durability performance significantly, its effects on mechanical properties were observed to be limited. However, NC replacement dosage of 3%, by weight of cement, can be considered as the optimal content for SCC in comparison with the NC replacement of 1% and 2%. In the second step of this experiment, the effects of 3% NC inclusion on properties of blended cement SCC containing optimum levels of SF, FA, RHA and GGBFS (15%, 30%, 15%, and 45%, respectively, based on literature) were assessed. The results indicated that by incorporating 3% NC in blended cement SCC, satisfactory workability and mechanical properties can be achieved. Remarkable enhancements were also observed in durability properties of blended cement SCC with the presence of NC compared to that of the reference concretes confirming that a small dosage of NC can effectively be used to make big improvements in the properties of environmentally friendly SCC mixes.