Positive Influence of Liquid Sodium Silicate on the Setting Time, Polymerization, and Strength Development Mechanism of MSWI Bottom Ash Alkali-Activated Mortars

Abstract

Setting time and mechanical properties are key metrics needed to assess the properties of municipal solid waste incineration (MSWI) bottom ash alkali-activated samples. This study investigated the solidification law, polymerization, and strength development mechanism in response to NaOH and liquid sodium silicate addition. Scanning electron microscopy and X-ray diffraction were used to identify the formation rules of polymerization products and the mechanism of the underlying polymerization reaction under different excitation conditions. The results identify a strongly alkaline environment as the key factor for the dissolution of active substances as well as for the formation of polymerization products. The self-condensation reaction of liquid sodium silicate in the supersaturated state (caused by the loss of free water) is the major reason for the rapid coagulation of alkali-activated samples. The combination of both NaOH and liquid sodium silicate achieves the optimal effect, because they play a compatible coupling role.

Preparation and Properties of Municipal Solid Waste Incineration Alkali-Activated Lightweight Materials through Spontaneous Bubbles

“…At the same time, the water absorption of specimen LYY-8 decreased to 12.3%, which is 25.3% lower than that of specimen LYY-7 (without LSS), indicating that LSS also has a water absorption reducing function. As LSS is a viscous liquid with good sealing and isolation function, it can seal and isolate microbubbles into independent bubble units, block penetration and linkage between bubbles, effectively prevent the infiltration of free water, and reduce overall water absorption [ 25 ]. Therefore, LSS not only plays an effective role in bubble fixation but also blocks the penetration between bubbles, which further reduces density and water absorption.…”

Effect of Sodium Hydroxide, Liquid Sodium Silicate, Calcium Hydroxide, and Slag on the Mechanical Properties and Mineral Crystal Structure Evolution of Polymer Materials

“…As a result, the intensities of the tobermorite and hillebrandite peaks did not increase significantly. Therefore, the formation of calcium silicate hydrate and hydrated calcium aluminosilicate gel in sample H-8 could not be continuously increased by increasing the GS content (26.4 MPa, 28 d, only 11.4% higher than that of sample H-7) [33]. Thus, the rate at which the compressive strength increased was significantly reduced upon continuously increasing the GS content in the same proportion.…”

Morphological and mechanical studies of Al2O3–Na2SiO3 as a skin barrier coated with TiO2 for carbon fiber reinforced composite materials

“…This process arises from the evaporation of the crystal water content in the skin barrier, causing the gas phase to try to escape, appearing as a burst air bubble. 34 The specimen thermograms (Fig. 6) showed a curve with a two-step weight reduction to the heating temperature.…”