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Your search keyword '"Chuiyuan Kong"' showing total 2 results
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2 results on '"Chuiyuan Kong"'

1. Effect of carbide slag and steel slag as alkali activators on the key properties of carbide slag-steel slag-slag-phosphogypsum composite cementitious materials

Author

Guihong Yang, Chao Li, Wangshan Xie, Yao Yue, Chuiyuan Kong, and Xiaolong Li

Subjects
carbide slag, steel slag, alkali activators, solid waste-based cementitious materials, mechanical properties, microstructure, Technology
Abstract

In order to enhance the utilization of alkaline carbide slag (CS) and steel slag (SS) in solid waste-based cementitious materials (SWBCM). In this study, slag (GGBS) was utilized as the primary material, phosphogypsum (PG) as the sulfat activator, and carbide slag (CS) and steel slag (SS) as the alkali activators to prepare carbide slag-steel slag-slag-phosphogypsum composite cementitious material (CS-SS-GGBS-PG). The impact of partial SS (mass fraction) substitution by CS on the flowability, mechanical properties, softening coefficient, pore solution pH value, hydration heat, and microstructure of CS-SS-GGBS-PG was studied. The hydration products, microstructure, and pore structure of CS-SS-GGBS-PG were studied via XRD, FTIR, TG-DTG, SEM, and MIP. The results show that CS replacement with SS decreases the flowability of CS-SS-GGBS-PG compared to the specimen without CS doping (A0). The addition of CS provides an abundance of Ca2+ and OH− to facilitate the hydration reaction in the system, prompting CS-SS-GGBS-PG to form more C-(A)-S-H gels and ettringite (AFt) in the early stages. This significantly enhances the 3 and 7 days strength of CS-SS-GGBS-PG. Compared to A0, the sample group with 5% CS substitution for SS showed a respective increase of 400% and 1,150% in flexural strength at 3 and 7 days, and an increase of 800% and 1,633% in compressive strength. However, if CS is substituted for SS in excess, the system’s late hydration process will be inhibited, increasing the volume of harmful pores in the specimen’s microstructure and lowering its degree of compactness. This leads to a decrease of 28 days of strength and a deterioration of the water resistance of CS-SS-GGBS-PG. It is advised that the blending ratio of SS to CS be 3:1 in order to maintain equilibrium between the early strength enhancement of CS-SS-GGBS-PG and the stability of strength and water resistance in the latter stage. This study has a positive impact on improving the utilization of CS and SS in SWBCM, reducing the dependence of SWBCM on traditional high-angstrom chemical alkali activators, and promoting the development of SWBCM.

Published
2024
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2. Preparation and Micromechanics of Red Sandstone–Phosphogypsum–Cement Composite Cementitious Materials

Author

Tang, Chuiyuan Kong, Bin Zhou, Rongxin Guo, Feng Yan, Rui Wang, and Changxi

Subjects
red sandstone, phosphogypsum, flowability, mechanical strength, micromechanics, volcanic ash activity
Abstract

Based on the physical and chemical properties of red sandstone (RS), RS is used to produce composite cementitious materials. The flowability, mechanical strength, and micromechanics of a red sandstone–cement binary cementitious material (RS-OPC) were investigated as functions of the amount of RS replacing the cement (OPC). Additionally, the feasibility of producing red sandstone–phosphogypsum–cement composite materials (RS-PG-OPC) using the phosphogypsum (PG)- enhanced volcanic ash activity of RS was investigated. The products of hydration and microstructures of RS-OPC and RS-PG-OPC were analyzed by XRD, FTIR, TG-DTG, and SEM. RS enhanced the flowability of RS-OPC relative to the unmodified cement slurry but lowered its mechanical strength, according to the experiments. When the quantity of OPC replaced was greater than 25%, the compressive strength after 28 days was substantially reduced, with a maximum reduction of 78.8% (RS-60). The microscopic mechanism of RS-OPC suggested that the active SiO2 in the RS can react with Ca(OH)2 to produce C-S-H but can only utilize small quantities of Ca(OH)2, confirming the low volcanic ash activity of RS. RS was responsible for dilution and filling. The incorporation of 5% PG into RS-PG-OPC slowed the hydration process compared with RS-OPC without PG but also increased the flowability and aided in the later development of the mechanical strength. This was primarily because the addition of PG provided the system with sufficient Ca2+ and SO42− to react with [Al(OH)6]3− to form ettringite (AFt), therefore accelerating the dissolution of Al3+ in RS to generate more AFt and C-(A)-S-H gels. To some extent, this excites the volcanic ash of RS. Therefore, if there is an abundance of waste RS in the region and a lack of other auxiliary cementitious materials, a sufficient quantity of PG and a finely powdered waste RS component can be used to replace cementitious materials prepared with OPC to reduce the mining of raw OPC materials.

Published
2023
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