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 fly ash (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 Na 2 SiO 3-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.

Synergic effect of metakaolin and groundnut shell ash on the behavior of fly ash-based self-compacting geopolymer concrete

“…Besides, 1.60 tons of raw materials [1] and about 6.50 million British thermal unit (BTU) of energy are needed for the making of one ton of PC and during its production, one ton of carbon dioxide is discharged into the environment, which destroys the atmosphere [2]. Hence, in order to protect the worldwide atmosphere from the influence of PC production, new opportunities must be found and explored to develop further ecologically friendly materials which possess the pozzolanic property and these types of materials can be utilized as replacements for PC in concrete [2][3][4][5]. To tackle the problem of global warming, the world has made tremendous efforts to decrease the use of PC.…”

“…In this regard, geopolymer concrete (GC) is one of the revolutionary developments associated with new materials, leading to inexpensive and environmentally friendly materials as alternatives to PC [3,34]. GC is an aluminosilicate-based inorganic polymer concrete that can be synthesized from geological materials or by-products rich in silicon and aluminium and having a strong alkaline solution [35].…”

“…Generally, a combination of sodium silicate and sodium hydroxide is taken as the alkaline activator. Sodium hydroxide (98-99% purity) and sodium silicate solution (Na2O = 14.26%, SiO2 = 29.43%, water = 56.31%) by weight [3,35]. However, the use of geopolymer technology is not only considerably decreases CO 2 releases in the cement industry, but also allows the use of industrial waste by-products of aluminosilicate compositions to produce value-added building materials [3,[36][37][38].…”

“…Sodium hydroxide (98-99% purity) and sodium silicate solution (Na2O = 14.26%, SiO2 = 29.43%, water = 56.31%) by weight [3,35]. However, the use of geopolymer technology is not only considerably decreases CO 2 releases in the cement industry, but also allows the use of industrial waste by-products of aluminosilicate compositions to produce value-added building materials [3,[36][37][38]. Geopolymers have excellent physical, chemical and mechanical properties which depend on the choice of raw materials and processing conditions.…”

“…Earlier, most of the research focused on the synthesis of geopolymers from MK [47][48][49]. However, FA is rich in silica and alumina and its use in the production of geopolymers is an important strategy for making concrete more environmentally friendly [3,50]. In fact, concrete depends on complete compaction especially for large and complex structures.…”