The Impact of Artificial Lightweight Aggregate on the Engineering Features of Geopolymer Mortar

Abstract

In this study, a research on the effectiveness of artificial lightweight aggregate (A-LWA) on the fresh and hardened properties of geopolymer mortars is presented. The main aim of this study is to propose a relatively newer means of recycling of FA through geopolymer mortar production. Therefore, firstly, artificial lightweight aggregate (A-LWA) was produced through the cold-bonding pelletization process of FA. Then, FA based geopolymer mortars were produced with this aggregate. The geopolymer mortars manufactured in this study had constant source material and alkaline activator quantities of 600 and 300 kg m-3, respectively. The proportion of Na2SiO3-to-NaOH was 2.5 and the molarity of NaOH was 12 M. The A-LWA sand was replaced partially with river sand up to 100%. The compressive strength, ultrasonic pulse velocity, fresh and dry densities of the geopolymer composites were measured at the age of 7 days and the flow table test was conducted to indicate the consistency of the geopolymer mixtures. The results indicated the A-LWA utilization enhanced the workability of the geopolymer mixtures and the highest increase of flow diameter of %20 was obtained using 100% A-LWA. Compressive strength values of geopolymer mortars varied between 4.28 and 32.3 MPa. A systematical decrease in the compressive strength and revealed with respect to the increasing level of A-LWA due to the softness and weakness of the A-LWA particles. Ultrasonic pulse velocity results of geopolymer mortars ranged from 1479 to 2596 m s-1 with related the replacement level of A-LWA.