Study of Hydration and Microstructure of Mortar Containing Coral Sand Powder Blended with SCMs

Abstract

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO3 can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar.

Environmental-friendly mortar produced with treated and untreated coal wastes as cement replacement materials

“…18(a)) due to the presence of calcium silicate hydrate (gel-like ocks) and calcium hydrate ( brouslike crystals). Previously, the formation of crystals of ettringite was observed in mortars containing supplementary cementitious materials as well (Nguyen et al 2021;Li et al 2020b), especially in the cement pastes with coal waste as a supplementary binder (Afrakoti et al 2020). It should be noted that the enhancement of mechanical strength is attained by a considerably more compact microstructure where pore space between unreacted particles is completely lled with dense webs of ettringite crystallites resulted from SCMs (Nguyen et al 2021).…”

“…Using these waste materials as a partial replacement of binder in concrete is an economical, ecological, and green remedy to save natural resources (Li et al 2020b). According to the literature (Li et al 2020b;Afrakoti et al 2020;Saeidi Rashk Olia and Perić, 2020;Mejia-Ballesteros et al 2019;Hassan et al 2019;Haghani et al 2019;Modarres et al 2018;Kočí et al 2016;Hesami et al 2016;Ramezanianpour, 2014;Frías et al 2012), previous studies have examined the cement substitution by SCMs, such as y ash, rice husk ash, waste ceramic dust, coal waste, and other human-made wastes materials. It is worth mentioning that the particle size of SCMs has a direct impact on the mechanical properties of hardened mortar.…”

“…18(c) and (d)) because of more hydration products such as calcium silicate hydrate and calcium hydrate. It has been reported that ner particles like TCW could enhanse the packing density of the cement matrix by developing the number of nucleation sites, led to an increase in the hydration products (Li et al 2020b).…”

Hydration and Mechanical Properties of Calcium Sulphoaluminate Cement Containing Calcium Carbonate and Gypsum under NaCl Solutions

“…CSA mortars blending with CaCO 3 had lower compressive strength than that of pure CSA mortars, and the trend seemed to become more obvious by increasing the content of CaCO 3 . CaCO 3 is mainly used as a filler, it basically does not participate in chemical reaction [40,50]. For CC5, the loss of strength was minimal when CaCO 3 is used.…”

Effects of Wet-Dry Alternation of Ocean Tide Environments on the Bond Behaviour of CFRP-Reinforced Coral Concrete

“…Using conventional aggregate to prepare concrete will greatly increase the project cost [1]. Using coral aggregate around offshore islands and reefs to prepare coral concrete can effectively solve the problem mentioned above [2,3]. Zhou [4] derived the constitutive relations of coral aggregate concrete under uniaxial and triaxial compression.…”