Orthogonal Experimental Studies on Preparation of Mine-Filling Materials from Carbide Slag, Granulated Blast-Furnace Slag, Fly Ash, and Flue-Gas Desulphurisation Gypsum

Mingyue Wu,Xiangming Hu,Zunxiang Hu,Qian Zhang,Weimin Cheng

doi:10.1155/2018/4173520

Abstract

Environmentally friendly and cheap composite green cementitious materials have been prepared from carbide slag, fly ash, flue-gas desulphurisation (FGD) gypsum, and granulated blast-furnace slag (GBFS) without using cement clinker. Orthogonal testing was used to investigate the effects of the raw materials on the amount of water required for reaching standard consistency and consistency, setting time, slump value, and strength of the produced materials after curing for 7 d and 28 d. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the analysis of the sample microstructure and hydration products as well as for the exploration of possible hydration mechanisms. We found that, among the utilised raw materials, the addition of FGD gypsum had the most significant effect on the setting time and amount of water required for reaching standard consistency and consistency, while the addition of GBFS deeply affected the slump value. The optimal activation results were obtained when the mass ratio of carbide slag : fly ash : GBFS : FGD gypsum was equal to 12.1 : 60.6 : 18.2 : 9.1.

Highlights

Owing to the increasing depletion of nonrenewable resources and effects produced by global warming, the high levels of energy consumption and pollution generated during the production of cement clinker have attracted widespread concern
Because carbide slag is rich in the alkaline calcium oxide and calcium hydroxide components, we hypothesised that it would provide a large number of OH− ions when used as an admixture of cementitious materials
The falling depth displayed on the consistometer dial corresponded to the consistency value for the cementitious material, and the measurement accuracy was 1 mm

Summary

Introduction

Owing to the increasing depletion of nonrenewable resources and effects produced by global warming, the high levels of energy consumption and pollution generated during the production of cement clinker have attracted widespread concern. The major component of FGD gypsum is calcium sulphate dihydrate At present, these industrial wastes are primarily utilised for the production of cement [1, 2], concrete [3,4,5,6,7], geopolymers [8,9,10], and cementitious materials for mine filling [11, 12]. Because carbide slag is rich in the alkaline calcium oxide and calcium hydroxide components, we hypothesised that it would provide a large number of OH− ions when used as an admixture of cementitious materials These ions can effectively destroy the acidic film formed on the surfaces of fly ash and GBFS particles, leading to the dissolution of various mineral constituents, such as silicon dioxide and aluminium oxide. In the present study, fly ash, carbide slag, GBFS, and FGD gypsum were used to prepare green cementitious materials without cement clinker. We hope that this study will contribute to the preparation and promotion of high-quality inexpensive cementitious materials for mine filling [18,19,20,21,22,23,24]

Materials and Methods

A: Ca2Al2SiO7

Testing Parameters

Results and Discussion

Amounts of Water Required for Reaching Standard

Conclusion