Using metakaolin-based geopolymer concrete in concrete pavement slabs

Geopolymer concrete is a new kind of environmentally friendly concrete. It gains early strength in room temperature without water curing, and by heating, strength continues to develop. This study investigates the possibility of using geopolymer concrete based on metakaolin (GPC) as a rigid pavement concrete slab material and as an efficient alternative to conventional Portland cement concrete (PCC). Different constitutes materials of GPC and PCC were tested to assure validity for use. Both GPC and PCC mixtures had 30 MPa compressive strength. GPC specimens were cured at room temperature, whereas PCC specimens were cured in water. GPC mixture was mixed at 2.5 alkaline solutions ratio, and the concentration of NaOH solution was 16 molar. The ratio of SiO2 to Na2O in Na2SiO3 solution was two. Compressive, flexural, and indirect tensile strength tests, as well as static modulus of elasticity, Poisson's ratio tests and resistance to fuel tests, were performed on both GPC and PCC specimens. To study the behavior of rigid pavement slabs, 800 x 800 x 50 mm GPC and PCC slabs were subjected to mechanical loading tests in three positions (interior, edge and corner). The slabs were supported by a set of steel springs under a 20-mm layer of recycled rubber which had the same surface dimensions of the tested slabs to simulate a subgrade with a modulus of reaction of 36 MPa/m. GPC exhibited a comparable performance with PCC in all investigated parameters in this study with higher rigidity and resistance to surface abrasion in fuel resistance test.