Development and Characteristics of Aerated Alkali-Activated Slag Cement Mixed with Zinc Powder

Abstract

Experiments on the development and properties of aerated concrete based on alkali-activated slag cement (AASC) and using Zn powder (ZP) as a gas agent were carried out. The experiments were designed for water-binding material (w/b) ratios of 0.35 and 0.45, curing temperatures of 23 ± 2 °C and 40 ± 2 °C, and ZP of 0.25%, 0.50%, 0.75%, and 1.0%. ZP generates hydrogen (H2) gas in AASC to form pores. At a w/b of 0.35, the curing temperature had little effect on the pore size by ZP. However, a w/b of 0.45 showed a clear correlation that the pore diameter increased as the curing temperature increased. The low w/b of 0.35 showed a small change in the pore size according to the curing temperature due to the faster setting time than 0.45 and the increased viscosity of the paste. Therefore, at a termination time exceeding at least 60 min and a w/b of 0.45 or more, it was possible to increase the size and expansion force of the pores formed by the ZP through the change of the curing temperature. ZP showed applicability to the manufacture of AASC-based aerated concrete, and the characteristics of foaming according to the curing temperature, w/b ratio, and ZP concentration were confirmed.

Monitoring the Geopolymerization Reaction of Geopolymer Foams Using 29Si and 27Al MAS NMR

“…Zinc powder can act as a reducing agent, which can reduce the oxidation state of some of the cations present in the starting materials used to make the geopolymer. This reduction can affect the condensation degree of the geopolymerization reaction [55], meaning that fewer of the available chemical bonds will be used to form the geopolymer network. As a result, the resulting geopolymer may have a lower degree of polymerization, which can lead to weaker mechanical properties.…”

Mathematical Modeling and Experimental Substantiation of the Gas Release Process in the Production of Non-Autoclaved Aerated Concrete

“…In terms of cost characteristics, non-autoclaved cellular concretes significantly outperform autoclaved competitors due to the significantly reduced cost of production and manufacture of such concretes and less environmental impact. From the point of view of technological and recipe factors, there are quite a lot of studies of non-autoclaved and autoclaved aerated concrete [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. However, from the point of view of fundamental science, some gaps should be filled with additional research in the phenomenon of outgassing during the formation of the structure of non-autoclaved aerated concrete.…”

“…Several works [ 31 , 32 , 33 , 34 , 35 ] are devoted to the macrostructure formation stage, the analysis of which shows that the determining influence on the formation of the porous structure of aerated concrete is exerted by the kinetics of gas release by the gasifier and the change in the rheological properties of the interpore material. Furthermore, studies of the swelling process to improve the quality of the macrostructure and improve the physical and mechanical properties of aerated concrete are currently aimed at an in-depth study and determination of the optimal combination of these kinetic processes.…”

Special Issue: “Recent Developments in Geopolymers and Alkali-Activated Materials”

“…Ibraheem et al [ 5 ] explore the diversification of raw materials in AAMs by adding quarry rock dust and steel fiber, presenting effective ways to recycle waste resources and enhance strength. Kim et al [ 6 ] manufacture a porous alkali-activated material using zinc powder as a foaming agent, introducing a novel reaction pathway compared to commonly used aluminum powder. Rozek et al [ 7 ] report on the performance of boroaluminaosilicate geopolymers in immobilizing heavy metals, surpassing traditional cement concrete in metal fixation capabilities.…”