Effects on Compressive Strenght of Accelerated Curing Methods in Alkali Activated Mortars

Abstract

The production of ordinary Portland cement (OPC) requires large amounts of fuel and raw materials and responsible about 7% total CO2 emissions in the earth's atmosphere. The handicaps of the production of OPCs can extinguish with a new type of green and eco-friendly material, namely, geopolymer. The aim of the study is to investigate compressive strength properties at accelerated curing conditions of alkali-activated slag/bottom ash mortars and different rates of rice husk ash. The ratio of blast furnace slag (YFC) / fly ash (UK) was chosen 100/0, 72.5 / 27.5, 45/55 and 7.5 / 92.5, and also the ratios of alkali (YFC + UK) / rice husk ash (PK) 0%, 2.5%, 5% and 7.5% were used. As the activator used Na2SiO4 (SS) and NaOH (SH) used was used at four different dosages, varying between 0/100%, 70/30%, 40/60% and 100/0%. Prepared using Taguchi L16 test design matrix for experimental study, and also the UK and PK to be used in the work were firstly grounded with sufficient fineness through a ball mill. The samples were poured into prismatic samples prepared in dimensions of 40 x 40 x 160 mm and thermal curing was applied at different temperatures and times. Compressive strength tests were applied on prepared 2, 7, 28 and 90 day samples. As a result of the study; it has been observed that the use of PK up to 7.5% gives favorable results in terms of compressive strength. The maximum compressive strength was obtained in 27.5% ratio of UK and 7.5% in SH and 30% in SH. However, in terms of the compressive strength, it is more appropriate to use 27.5% of the UK ratio.

Keywords: Geopolymer, Fly Ash, Slag, Sodium Silicate, Sodium Hydroxide, Compressive Strength