Experimental study on segregation resistance of nanoSiO2 fly ash lightweight aggregate concrete

Lightweight aggregate concretes (LWACs) of strength grade raging from LC40 to LC50 were prepared by adding different proportions of fly ash and nanoSiO2. Segregation resistance of LWAC was studied by slump and segregation degree tests. The results indicate that adding of finer fly ash enhances the fluidity of LWAC and enlarges the slump, meanwhile, with the increase of fly ash content, segregation degree of concrete is decreased and floating of lightweight aggregate is somewhat alleviative but still exists; adding of nanoSiO2 improves the segregation resistance of LWAC to a certain extent, but deteriorates the fluidity of concrete mixture; combined admixture of nanoSiO2 and fly ash not only increases the slump of LWAC, but also improves its segregation resistance, prevents the floating of lightweight aggregate and makes concrete show better homogeneity. Mechanical property tests indicate that combined admixture of nanoSiO2 and fly ash improves the compressive strength, increases the tension-compression ratio and reduces the brittleness of concrete.