Assessing properties of alkali activated GGBS based self-compacting geopolymer concrete using nano-silica

Empirical studies were done to develop alkali activated Self-Compacting Geopolymer Concrete (SCGC) using Ground Granulated Blast furnace Slag (GGBS), incorporated with 2 % nano silica by weight, through evaluation of its fresh and hardening properties. Experimental investigation on 6 mix designs of varying molarity of 10M, 12M and 16M of alkaline solution and binder content of 450 Kg/m3 and 500 Kg/m3 were done and compared with GPC mix design composed of 16M alkaline solution concentration and 500 Kg/m3 binder content without nano silica. The Sodium Silicate to Sodium Hydroxide ratio (SS/SH), Alkaline Activator Liquid to Binder ratio (AAL/B) and Water to Binder Ratio (W/B), which significantly affect the performance and mechanical properties of GPC, were fixed at 2.5, 0.45 and 0.27 respectively. To catalyze the early stage geopolymerisation, oven curing was done maintaining the temperature at 60 ˚C. This paper also elucidates the test results for fresh Self-Compacting Concrete (SCC) done as per guidelines established in EFNARC. Mechanical tests conducted were compressive strength test after 7, 28, 56 and 90 days; split tensile strength test and flexure test after 28, 56 and 90 days; X-ray diffraction test to analyze the mechanical performance and sorptivity test for testing of permeability. The study revealed that the sample of 16M concentration of alkaline solution with 500 Kg/m3 binder content containing 2% nano silica produced the highest compressive, flexural and split tensile strength of 81.33 MPa, 7.875 MPa and 6.398 MPa respectively at 90 days.