Rice husk ash blended self-consolidating concrete for application in rigid pavements: transforming agro-industrial waste into environment-friendly and sustainable material

The production of industrial wastes, including those generated from agro-industry, and their improper disposal cause environmental concern. On the other hand, the construction of large road networks demands a huge amount of construction materials. Synergetic relationships encourage a closed system approach that involves the reuse of waste from one industry as a raw material for another, which is a vital tool for industrial revamp. Thus, in this study, energy-saving semi-flowable self-consolidating concrete (SF-SCC), using an agro-industrial waste rice husk ash (RHA) as a substitution for cement, is evaluated for its utilisation in slip-form construction of pavements. The study involved mix design, testing of fresh properties (including rheology using direct shear test) and strength and durability properties of SF-SCC with RHA at 10–50% by weight of cement. Furthermore, microstructural analysis was also carried out for the optimum mixes. The results indicate that RHA up to 20% is found to be the optimum level of replacement for cement. The compressive strength (CS) corresponding to 7 and 28 days of curing in respect of all the mixes is observed to be above 7 and 40 MPa, respectively, and the flexural strength (FS) at 28 days of curing is above 4.5 MPa. The water absorption (WA) with respect to all the mixes is found to be less than 5%; the chloride penetration is found to be in the range of ‘low’ to ‘very low’. Thus, in accordance with the norms contained in Indian Roads Congress (IRC) specifications, all six SF-SCC mixes can be efficiently used as a green material for pavement construction either in village areas or urban areas. Moreover, analytical studies to correlate the strength results and Technique of Order Preference by Similarity to Ideal Solution (TOPSIS) to rank the performance of mixes are also reported.