The effect of nano-silica on the gas permeability, durability and mechanical properties of high strength lightweight aggregate concrete

In this current study, we carried out an experimental investigation on the effect of nano-silica on the gas permeability, durability and mechanical properties of high strength lightweight concrete. The experimental analysis consists of two parts. The first part is the production of lightweight aggregate by using cold bonded method and the second part is the design of different mixes of concrete samples. The lightweight aggregate through cold bonded method is produced after three processes. The first process is started with by mixing 90% of cement replacement material fly ash class (F) with 10% Portland cement by weight. The second process is pelletization of lightweight aggregates by moisturing in pelletized machine at ambient temperature and final stage is the curing process at 28 days. Utilization of light weight aggregate has been finished off by volumetric substitution of normal coarse aggregate with 5 different percentages (0%, 10%, 20%, 30% and 40%) with and without nano-silica (SiO2). It has been used with a constant water/binder and fly ash (FA) ratios as 0.35 and 0.2, respectively. By the way, the properties of concrete has been investigated independently for each different percentages of lightweight aggregate. All mechanical properties; compressive strength and splitting tensile strength were monitored and physical properties like sorptivity and gas permeability were measured at the ages of 28 and 90 days. The results indicates that the negative results of LWAs can be remedied by addition 3% of nS particles that leads to increase the efficiency.