A study on development of pavement quality geopolymer concrete for low volume roads

Abstract

The world's rural roads are extensively interconnected with all conventional OPC (Ordinary Portland cement) concrete roads and with little traffic. The main ingredient in concrete pavements is ordinary Portland cement which has serious environmental issues like CO2 emissions during the production. A replacement for traditional cement-based concrete is available in the form of geo-polymer concrete (GPC). The current work mainly emphasis on the mix development of Fly Ash (FA)-Ground Granulated Blast Furnace Slag (GGBFS) based GPC for rigid pavements application in low volume concrete roads (LVCR). The study consists of preparing GPC mixes with total of 8 combinations comprising GGBFS and fly-ash as binders (GGBFS-40% and 50% replacement to FA), two different alkaline solution/binder ratio (As/Bi = 0.45 and 0.50) and sodium hydroxide (NaOH) solutions of 8 and 10 Molarities with a constant proportion of sodium silicate (Na2SiO3) by sodium hydroxide (NaOH) is 2.5 by 1. All the specimens were kept under outdoor curing only. The guidelines by IRC:SP:62-2014 recommended that the characteristic compressive strength of concrete at 28 days used to pave ruralcountry roads be at least 30 MPa, while the 28 days flexural strength should not be less than 3.8 MPa. From the experimental study it was noticed that, when the GGBFS content and NaOH molarity increases, the mix’s workability is getting reduced and mechanical properties were improved significantly whereas when the As/Bi increases from 0.45 to 0.50, the mix workability increases and also mechanical properties too. And also concluded that, the FA-GGBFS based GPC mix for low volume concrete roads is attained with GGBFS content 40% to 50% replacement for fly ash and NaOH Concentration of 10 M with a binder content of 400 kg/m3 at an As/Bi ratio of 0.45 and 0.50 are adequate to meet the requirements for low volume concrete road standards.