volume changes of lightweight aggregate concrete due to the combined usage of micro- and nano-silica

Concrete's considerable density, which makes concrete constructions more seismically vulnerable, isone of its key drawbacks. Replacing lightweight aggregates with normal ones in concrete buildings is oneof the conventional techniques for lighting concrete constructions. Inadequate rigidity and excessiveporosity of lightweight aggregates result in a rise in the expansion and shrinkage of the concrete andcorrespond to a loss in the durability of the concrete. In this research, it is anticipated that concrete wouldexpand and contract more owing to the entire substitution of ۴–۱۰ mm LECA with gravel. Due to the provensynergistic impact of combining micro- and nano-silica in the optimum percentage, Utilizing the methodabove, the decrease of volume changes in lightweight aggregate concrete was studied. The quantity ofmicro-silica was set at ۱۰ % by weight of cement, whereas the levels of nano-silica were regarded to be۰.۵%, ۱, ۱.۵%, and ۲%. Tests of expansion and shrinkage were conducted on days ۳, ۷, ۲۸, and ۹۰. Theresults of the tests reveal that the mixing design of ۱۰%Ms+۱%Ns is the optimal design for expansion andshrinkage tests, with volume changes of ۵۸% and ۷۱%, respectively, at the age of ۹۰ days.

Keywords:

Lightweight aggregate concrete , Micro-silica , Nano-silica , synergic effect , expansion , shrinkage