Preparation and Properties of a Sulphoaluminate Magnesium-Potassium Phosphate Green Cementitious Composite Material from Industrial Solid Wastes.

Changzai Ren,Dongliang Hua,Wenlong Wang,Yonggang Yao,Shuang Wu

doi:10.3390/ma14237340

Changzai Ren, Dongliang Hua + Show 3 more

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https://doi.org/10.3390/ma14237340

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Abstract

The preparation of high-performance green cementitious material from industrial solid waste is a feasible large-scale utilization approach for industrial solid waste. This work investigates the feasibility of using industrial solid wastes in a sulphoaluminate–magnesium–potassium–phosphate cementitious composite material (SAC-MKPC) clinker preparation and the influence of the calcination temperature and clinker ingredients on the hydration behavior and mechanisms of the SAC-MKPC with a Mg/P ratio of 5. The results show that the novel SAC-MKPC that was prepared from aluminum slag, carbide slag, coal gangue, and magnesium desulfurization slag was composed mainly of mineral MgO, , and C2S and the calcination temperature of the main mineral phases was 1250–1350 °C. The solid-waste-based SAC-MKPC had better mechanical properties and excellent water resistance compared with the MKPC. The optimal compressive strength reached 35.2, 70.9, 84.1, 87.7, and 101.6 MPa at 2 h, 1 d, 3 d, 7 d, and 28 d of hydration, respectively. The X-ray diffraction spectra and scanning electron micrographs of the hydration products of the SAC-MKPC clinker showed that AFt and K-struvite crystals coexisted and adhered to form a dense structure. This work provides an innovative idea to produce green cementitious material using industrial solid wastes and may promote the sustainable development of the power and mining industries.

Highlights

The electrolytic aluminum, power, and mining industries produce large volumes of solid waste [1]
We investigated the possibility of producing SAC-MKPC clinker from magnesium sulphate, calcium oxide, and aluminium oxide in different proportions, at low calcination temperatures, and using chemical reagents as raw materials [15]
When the calcination temperature was lower than 1250 ◦ C, periclase (MgO), dicalcium silicate (Ca2 SiO4 ), residual anhydrite (CaSO4 ), less mineral-phase magnesia alumina spinel (MgAl2 O4 ), and merwinite (Ca3 MgSi2 O8 ) were produced in the SAC-MKPC clinker system, but ye’elimite was not produced

Summary

Introduction

The electrolytic aluminum, power, and mining industries produce large volumes of solid waste [1]. The preparation of eco-friendly construction materials from industrial solid waste is a feasible large-scale utilization method using current technologies [3]. Magnesium-potassium phosphate cement (MKPC) is an excellent air-hardening cementitious material with a wide range of applications, including urgent construction and repair, nuclear waste encapsulation, and three-dimensional printing building materials; the high energy consumption and poor water resistance of MKPC have constrained its application in engineering [4,5,6]. In filling experiments and theoretical research, fly ash, nickel slag, and silica fume have been used as filling materials owing to their beneficial effects on improving the fresh mixture’s workability and reducing the development of heat in MKPC-based blends, which led to a more compact microstructure of hardened

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