Improving the Properties of Porous Geopolymers Based on TPP Ash and Slag Waste by Adjusting Their Chemical Composition

Abstract

The possibility of improving the properties of porous geopolymer materials based on ash and slag waste from thermal power plants by adjusting their chemical composition is considered. An X-ray phase analysis of ash and slag wastes was carried out, the geopolymers’ precursor compositions were calculated, and additives to correct their chemical composition were selected. The samples were synthesized and their physical and mechanical properties (density, porosity, compressive strength, thermal conductivity) were analyzed. The micro- and macro-structure of the samples and the pore distribution of the obtained geopolymers were studied and pore-distribution histograms were obtained. The influence of Si:Al ratio on structural changes was described. The geopolymers’ phase composition was studied, consisting of an amorphous phase and high quartz and mullite. A conclusion about the applicability of this method for obtaining high-quality porous geopolymers was made.

Study on the Curing and Foaming of Surfactant-Modified Geopolymer Gels Based on Ash and Slag Waste from Coal Combustion

“…However, in the study by Xinyu Li [57], the minimum density For alkaline activation of aluminosilicate materials, a mixture of waterglass (sodium hydrosilicate mNa 2 O•nSiO 2 •pH 2 O, silicate modulus = 2, water content 53 wt.%, LONTREK, Moscow, Russia) was used as an activating agent along with a solution of NaOH. As previous studies by the authors have shown [64,65], the optimal molar concentration of NaOH solution ranges from 8 to 12 M, as further increase reduces the compressive strength of foamed geopolymer materials. This conclusion is also supported by research from other authors [66,67].…”

“…The thermal conductivity of the geopolymers was measured using a thermal conductivity meter (ITP-MG4"100/Zond", SKB StroyPribor, Chelyabinsk, Russia) employing the stationary heat flow method. The temperature of the hot and cold faces was set at 34 where λ-effective thermal conductivity, W/m•K; H-sample height, cm; q-density of stationary heat flux passing through the measured sample, W/m 2 ; T H -temperature of the sample's hot face, K; T C -temperature of the sample's cold face, K. The methodology and equipment necessary for determining the linear dimensions as well as certain physical-mechanical properties (volume, density, porosity, compressive strength) of porous geopolymers were described in the authors' previous research [26,64]. Each recorded test value is the medium of 4 measurements.…”

Current State of Coal Fly Ash Utilization: Characterization and Application

“…Yatsenko et al [6] provided an article entitled "Improving the Properties of Porous Geopolymers Based on TPP Ash and Slag Waste by Adjusting Their Chemical Composition". The possibility of improving the properties of porous geopolymer materials based on ash and slag waste from thermal power plants by adjusting their chemical composition is considered.…”

Recycling of Coal Combustion Waste through Production of Foamed Geopolymers with Improved Strength

“…Several countries have already identified limited applications for these waste materials, including their use in ceramic production and cement manufacturing, as concrete additives and ameliorants, for road and dam construction, etc. [1][2][3]. In terms of chemical composition, coal combustion wastes (CCWs) exhibit a complex matrix, containing oxides of silicon, aluminum, iron, magnesium, and others.…”