Formation of C-S-H in calcium hydroxide–blast furnace slag–quartz–water system in autoclaving conditions

Abstract

In masonry, the most commonly used materials are concrete blocks or burnt clay brick. Owing to energy costs, there is a need to explore alternative raw materials and energy-efficient technologies for making building materials. This paper deals with the incorporation of blast furnace granulated slag in sand-lime materials as a replacement for hydrated lime during autoclaving conditions. The slag grain-size grinding and the heat treatment in saturated vapour pressure autoclave conditions were investigated to study the compressive strength behaviour of the new material.This substitution induces a decrease in compressive strength. The reaction products consist mainly of 11 nm tobermorite and xonotlite. The X-ray diffractions of these phases are difficult to see. The slag seems more reactive with lime than quartz. Observations with the scanning electron microscope allow better appreciation of these crystallites. With its composition and amorphous structure, the granulated slag does not release new distinct phases of hydrates.

Mechanical and microstructure characteristics development of hardened oil well cement pastes incorporating fly ash and silica fume at elevated temperatures

“…And so, more stable hardened OWC matrices (OWC-FA and OWC-SF) with enhanced mechanical characteristics under severe conditions of pressures and temperatures are attained [30]. Evidently, as previously reported by many researchers that CSH gel has an average value of C/S ratio equals to 1.5 [8] and to avoid the unsatisfactory phase transformation (amorphous CSH into crystalline α-C 2 SH or jaffeite) under the effect of high temperatures and pressures, CaO/SiO 2 (C/S) ratio has to be diminished to about 1 [9][10][11]. In our study, using SF or FA as supplements motivates the development of stable and desirable hydration products that possess lower C/S ratio (like tobermorite, Ca 5 Si 6 (OH) 2 .4H 2 O) through calcium hydroxide consumption [12,13].…”

“…It has been disclosed that CSH gel has an average value of the C/S ratio equals to 1.5 [8]. And so, the key role to hinder the unsatisfactory phase transformation (amorphous CSH into crystalline α-C 2 SH or jaffeite) was through diminishing CaO/SiO 2 (C/S) ratio to about 1 [9][10][11]. Many researches proved that various supplements as SF [12], fly ash [13], silica flour [14] and other silica-based ingredients [15][16][17][18][19][20][21][22][23][24] motivate the advancement of stable and desirable hydration products that possess lower C/S ratio (like tobermorite) through calcium hydroxide (CH) consumption.…”

Application of an Acrylic Polymer and Epoxy Emulsion to Red Clay and Sand

“…A tobermorite crystal is formed by providing lime (Ca 2+ ); it is one of calcium silicate hydrate [ 36 ], which reacted at a low temperature. There are many formations of calcium silicate hydrate; a formation is affected by the temperature and mole ratio [ 37 ]. Figure 13 illustrates various formations of calcium silicate hydrate, according to the temperature and mole ratio.…”

A First-Principles Study on Electronic, Thermodynamic, and Dielectric Properties of Monolayer Ca(OH)2 and Mg(OH)2

“…In contrast to SiO 2 , due to the positive heat of solution in M(OH) 2 materials, their solubility decreases with increasing temperature [81]. Although at room temperature the solubility of Ca(OH) 2 (∼ 1.09 × 10 −1 g/ml) is significantly higher than the solubility of amorphous SiO 2 (∼ 1.2 × 10 −4 g/ml), the solubility of both in water is the same at around 400 K [81,83].…”