Design of Inorganic Polymer Mortar from Ferricalsialic and Calsialic Slags for Indoor Humidity Control

Abstract

Amorphous silica and alumina of metakaolin are used to adjust the bulk composition of black (BSS) and white (WSS) steel slag to prepare alkali-activated (AAS) mortars consolidated at room temperature. The mix-design also includes also the addition of semi-crystalline matrix of river sand to the metakaolin/steel powders. The results showed that high strength of the steel slag/metakaolin mortars can be achieved with the geopolymerization process which was particularly affected by the metallic iron present into the steel slag. The corrosion of the Fe particles was found to be responsible for porosity in the range between 0.1 and 10 µm. This class of porosity dominated (~31 vol %) the pore network of B compared to W samples (~16 vol %). However, W series remained with the higher cumulative pore volume (0.18 mL/g) compared to B series, with 0.12 mL/g. The maximum flexural strength was 6.89 and 8.51 MPa for the W and B series, respectively. The fracture surface ESEM observations of AAS showed large grains covered with the matrix assuming the good adhesion bonds between the gel-like geopolymer structure mixed with alkali activated steel slag and the residual unreacted portion. The correlation between the metallic iron/Fe oxides content, the pore network development, the strength and microstructure suggested the steel slag's significant action into the strengthening mechanism of consolidated products. These products also showed an interesting adsorption/desorption behavior that suggested their use as coating material to maintain the stability of the indoor relative humidity.

Role of Heat-Treated Laterite on the Strengthening of Geopolymer Designed with Laterite as Solid Precursor

“…However, the final material has still a composite microstructure with a matrix phase having a gel structure where coarse aggregates of unreacted phases are distributed. Their quantities and distribution are parameters that favor the optimization of material properties [50,51]. Since larger zones of the matrix phase are detrimental to strength, this work show that a limited fraction of a heat-treated laterite must be added (30 wt% of LN500) to attain a value of 18.25 MPa that meets the standard mechanical strength [52].…”

Characterization of red mud/metakaolin-based geopolymers as modified by Ca(OH)2

“…These absorptions have been attributed to both atmospheric and bound water in geopolymers. 10,11 The bands at 1424 cm -1 and 878 cm -1 point to carbonate presence. 12 This is probably caused by the reaction of atmospheric CO 2 with calcium hydroxide (band at »878 cm -1 ) (sample GPRM1 and sample GPRM2).…”

“…Some authors reported that geopolymers are focused on the behavior of Si-O-Si and Si-O-Al bands. [10][11][12][13] Taking a straightforward approach, the identification of the position of the main Si-O-T (T=Si or Al) asymmetric stretching vibration (the strongest band) is here defined as the point of maximum absorbance in the region 1250-950 cm -1 and at 420-500 cm -1 . These peaks will be referred to as the "main band" in the spectrum of the geopolymers.…”

Influence of red mud and waste glass on the microstructure, strength, and leaching behavior of bottom ash-based geopolymer composites

“…This might suggest the formation of some new sixfold-coordinated ferric sites most probably located at amorphous gel-like phases 40 . These amorphous iron-rich phases have different structural characteristics than the typical aluminosilicate structure of the geopolymer gel, and certainly the presence of iron into the adhesive bonds influences the overall strength of the geopolymer composite 41 . www.nature.com/scientificreports/ Leachability.…”