Influence of Waste Glass Powder Addition on the Microstructure and Mechanical Properties of Autoclaved Building Materials

Lime quartz samples in which ground quartz sand was gradually substituted with waste glass powder (GP) were obtained under hydrothermal conditions to determine the influence of GP addition on the microstructure (observed by SEM), phase composition (analyzed by XRD), and compressive strength of autoclaved building materials. An additional series containing analytical grade NaOH and no GP was formed to evaluate the effect of sodium ions on tobermorite formation and its impact on the mechanical properties of the samples. GP addition hindered the formation of tobermorite during autoclaving. Instead, a higher amount of an amorphous and semi-crystalline C–S–H phase formed, leading to the densification of the composite matrix. Nevertheless, tobermorite-like structures were found during both XRD and SEM analyses, proving that the presence of small amounts of Al3+ ions allowed, to an extent, for the stabilization of the phase despite the high sodium content. The compressive strength values indicate that the presence of alkali in the system and the resulting formation of additional portions of C–S–H have a beneficial influence on the mechanical properties of autoclaved composites. However, the effect fades with increasing glass powder content which, together with a slight expansion of the samples, suggests that at high sand substitution levels, an alkali–silica reaction takes place.

Flexural Behaviour of Reinforced Geopolymer Concrete Incorporated with Hazardous Heavy Metal Waste Ash and Glass Powder

The flexural behavior of Incinerated Bio-Medical Waste Ash (IBWA) – Ground Granulated Blast Furnace Slag (GGBS) based Reinforced Geopolymer Concrete (RGPC) beams with Waste Glass Powder (WGP) as fine aggregate is explored in this research. The fine aggregate (M-Sand) is substituted by varying the waste glass powder as 0 percent, 5 percent, 10 percent, 15 percent, 20 percent, 25 percent, 30 percent, 35 percent, 40 percent, 45 percent, and 50 percent, and the mixture is cured under atmospheric curing. The impact of the WGP weight percentage on the flexural behavior of GPC beams is analyzed. The conduct of RGPC beams varies from that of ordinary Portland Concrete (OPC) beams, which is defined and examined. Deflection, ductility factor, flexural strength, and toughness index were measured as flexural properties for beams. In contrast to the reference beams, the RGPC beams containing 50% Waste Glass Powder as fine aggregate demonstrated a major increase in cracking resistance, serviceability, and ductility, according to the experimental finding. The RGPC beam without WGP ended in failure with a brittle manner whereas those beams with WGP encountered ductile failure. The RGPC beams' load ability improved by up to 50% as the weight percentage of WGP was enhanced.

Influence of Alkali Activator Type on the Hydrolytic Stability and Intumescence of Inorganic Polymers Based on Waste Glass

The main objective of this study is the synthesis and characterization of low cost alkali-activated inorganic polymers based on waste glass (G-AAIPs) using a mixture of NaOH and Ca(OH)2 as alkali activators, in order to improve their hydrolytic stability. This paper also presents detailed information about the influence of composition determined by X Ray Diffraction (XRD), microstructure determined by Scanning Electronic Microscopy (SEM) and processing parameters on the main properties of G-AAIP pastes. The main factors analyzed were the glass fineness and the composition of the alkaline activators. The influence on intumescent behavior was also studied by heat treating of specimens at 600 °C and 800 °C. The use of Ca(OH)2 in the composition of the alkaline activator determines the increase of the hydrolytic stability (evaluated by underwater evolution index) of the G-AAIP materials compared to those obtained by NaOH activation. In this case, along with sodium silicate hydrates, calcium silicates hydrates (C-S-H), with good stability in a humid environment, were also formed in the hardened pastes. The highest intumescence and an improvement of hydrolytic stability (evaluated by underwater evolution index and mass loss) was achieved for the waste glass powder activated with a solution containing 70% NaOH and 30% Ca(OH)2. The increase of the waste glass fineness and initial curing temperature of G-AAIPs have a positive effect on the intumescence of resulted materials but have a reduced influence on their mechanical properties and hydrolytic stability.