A simplified mix proportioning method for structural grade lightweight concrete using sintered flyash lightweight aggregate

Abstract

Structural concrete of a designed strength can be produced for specific requirements by using the accepted methods of mix design but the present Indian standards on mix design does not takes into account the procedure for mix design of sintered flyash lightweight coarse aggregate based concrete. The sintered flyash lightweight aggregate mainly produced from ash generated from coal based thermal power plants has higher water absorption and lower specific gravity. The mix proportioning of sintered flyash lightweight coarse aggregate based concrete is reported to be cumbersome and less accurate than normal weight concrete as the water absorption characteristics of these aggregates is a main concern. The current study has been done to develop a simplified mix design procedure for production of structural grade lightweight concrete using commercially available sintered flyash lightweight aggregate. The study also highlights the procedure for corrections need to be done with respect to higher water absorption characteristics of sintered flyash lightweight aggregate taking into account effect of cement paste during concrete mix proportioning. Based on the developed mix design method, a trend of 28-day cube compressive strength versus w/c for sintered flyash lightweight aggregate based concrete has been plotted for wide range of w/c from 0.3 to 0.7 and compared with curve given in IS: 10262-2019 for normal weight concrete.