Microstructure of Dry Mortars without Cement: Specific Surface Area, Pore Size and Volume Distribution Analysis

Abstract

The evolution of the microstructure of the wastepaper sludge ash-based dry-mortar mixtures is characterized. Mixtures have been prepared with a large volume of wastepaper sludge ash (WSA) and ground granulated blast-furnace slag (GGBS) as a binder matrix mixed with water. Two ratios of water/binder (w/b) = 0.5 and 0.6 were selected. Both of these two industrial by-products are well-known as supplementary cementitious materials in the construction industry and they constitute a convenient replacement for cement. A series of these dry mortars for two ratios w/b were activated by three different chemical activators. They were placed in 4 × 4 × 16 cm3 molds and then compacted at the same compaction energy of 600 kN·m/m3. The influence of water quantity, compaction level and activators on the microstructure of these mortars was investigated by measuring the specific surface area, pore size and volume. Different series of samples have been compared in terms of adsorption/desorption hysteresis and pores network. The influences of water quantity and energy level were first discussed on non-activated dry mortars and this analysis led to the selection of an optimal energy for the comparative study of activated dry mortars. A significant difference in behavior was observed between the studied activators in terms of specific surface area, adsorption property and pore distribution. Then, the microstructure of the three activated dry mortars is observed and analyzed considering the two w/b ratios, the mechanical strength obtained and the type and dosage of activator used. Dry mortars show micropores regardless the quantity of water and the dosage of activator.

Utilizing Sewage Sludge Slag, a By-Product of the Circulating Fluidized Bed Combustion Process, to Efficiently Remove Copper from Aquatic Environment

“…When the copper ions have already been adsorbed at least once, the interaction of the copper ions with the slag adsorbent has a favorable influence on the adsorption of remaining copper ions. As a result, the isotherm bulges in the direction of the pressure axis [43]. The BET and BJH analyses revealed the following results: specific surface area of 1.87 m 2 /g, pore volume (Vp) of 0.0096 cm 3 /g, and mean pore diameter (Apd) of 21.2 nm.…”

“…When the copper ions have already been adsorbed at least once, the interaction of the copper ions with the slag adsorbent has a favorable influence on the adsorption of remaining copper ions. As a result, the isotherm bulges in the direction of the pressure axis [43]. The SEM and TEM photographs of the samples are shown in Figures 8 and 9, respectively, showing flocs of irregular shape and different sizes.…”

Investigation of Mechanical Properties of Ultra-High-Performance Polyethylene-Fiber-Reinforced Recycled-Brick-Aggregate Concrete

“…The hysteresis loop is a unique phenomenon during the adsorption-desorption process, reflecting the irregularity and complexity of the material's pore structure. The hysteresis loop is larger and more elongated in RA, indicating larger pores and a better connectivity [37]. This rough structure and these adsorption properties allow cement particles to penetrate the surface of RA more efficiently, with a penetration depth of approximately 120 µm [38].…”