Mechanical, microstructure and reaction process of calcium carbide slag-waste red brick powder based alkali-activated materials (CWAAMs)

Cong, Peiliang; Cheng, Yaqian; Ge, Wanshuai; Zhang, Anyu

doi:10.1016/j.jclepro.2021.129845

Cited by 50 publications

(5 citation statements)

References 44 publications

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“…With the gradual prolongation of the age of curing, the absorption peak here is gradually weakened, and combined with the XRD test results, this shows that, with the prolongation of the age of curing of the cementitious systems, CCR is more involved in the pozzolanic reaction and its content is gradually reduced. The absorption peaks near 3420 cm −1 and 1650 cm −1 are mainly H-O-H bond stretching vibrations and bending vibrations [34,35], respectively, mainly caused by the hydroxyl group of crystalline water in the cementitious systems, and it can be seen from the figure that the 3442 cm −1 and 1650 cm −1 peaks decreased substantially with the increase in the age of curing, which is consistent with the literature [36]. The spectral band near 1420 cm −1 is caused by the vibration of C-O bonds in calcite [37]; it is mainly generated due to the hydration of CCR and SS in the raw material to generate Ca(OH) 2 and the carbonation reaction with air.…”

Section: Hydration Products and Chemical Structure Of Cementitious Sy...supporting

confidence: 90%

Study on the Properties and Hydration Mechanism of Calcium Carbide Residue-Based Low-Carbon Cementitious Materials

Wang,

et al. 2024

Buildings

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Alkali-activated cementitious materials, as an environmentally friendly cementitious material, can effectively reduce carbon emissions and improve the utilisation of solid wastes. However, traditional strong alkali activators have limitations such as high carbon emissions and poor safety. In order to overcome the defects of traditional strong alkaline activators and realise the high value-added use of calcium carbide residue (CCR), this paper adopts CCR as an alkaline activator to activate granulated blast furnace slag (GBFS)-steel slag (SS) cementitious systems for the preparation of alkaline-activated cementitious materials. The effects of CCR content and SS content on the compressive strength and working performance of CCR-GBFS-SS cementitious systems are analysed, along with the hydration process of CCR-GBFS-SS cementitious systems and the mechanism of action through the hydration products, their chemical structure and their microscopic morphology. The research results show that CCR-GBFS-SS cementitious systems have a 28-day compressive strength of 41.5 MPa and they can be controlled by the setting time; however, the flow performance is poor. The SS content can be increased to improve the flow performance; however, this will reduce the compressive strength. In CCR-GBFS-SS cementitious systems, CCR is the main driving force of hydration reactions, GBFS mainly provides active silica and aluminium and the amorphous C-(A)-S-H gel and ettringite formed by the synergistic action of multiple solid wastes are the main sources of compressive strength. With the extension of the curing time, the amount of hydration products in the cementitious systems gradually increases and the matrix of the cementitious systems gradually becomes denser. This study will provide a reference for the consumption of low-value solid waste such as CCR and the preparation of low-carbon cementitious materials from multi-component solid wastes.

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Section: Hydration Products and Chemical Structure Of Cementitious Sy...supporting

confidence: 90%

Study on the Properties and Hydration Mechanism of Calcium Carbide Residue-Based Low-Carbon Cementitious Materials

Wang,

et al. 2024

Buildings

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“…Therefore, the smaller volume of mesopores in SF5 is primarily due to the filling of pores at room temperature. The porosity occupied by the macropores in SF5 is also lower than that of F7M3, namely 9.26%, indicating that the stronger thermal stability of SF5 reduces the pore collapse at high temperatures [ 38 ].…”

Section: Resultsmentioning

confidence: 99%

“…Thus, it hinders the ions transport and declines the geopolymerization process, and it also results in enlarged shrinkage, deformation, microcracks, and early-stage damage [30,37]. As the silica fume content continues to rise further, there is a slight enhancement in compressive strength, probably due to the fine filler effect to refine the pore structure [38,39]. Figure 7b shows the compressive strength results of the blended precursor geopolymers from F9S1 to F5M5 after calcination temperatures between 20 °C and 800 °C.…”

Section: Compressive Strengthmentioning

confidence: 99%

Synergistic Effect of Blended Precursors and Silica Fume on Strength and High Temperature Resistance of Geopolymer

Cao,

Li,

2024

Materials

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This paper investigates the high temperature resistance performance and mechanism of potassium-activated blended precursor geopolymer with silica fume. The failure morphology, volume, and mass loss, compressive strength deterioration, hydration production, and pore structure are measured and analyzed. The results show that introducing slag into fly ash-based geopolymer could greatly improve the 28 d compressive strength but reduce the thermal stability. In contrast, the partial substitution of fly ash by metakaolin contributes to excellent high temperature resistance with slightly enhanced 28 d compressive strength. After being exposed at 800 °C, the residual compressive strength of F7M3 remains at 37 MPa, almost 114% of the initial ambient-temperature strength. An appropriately enlarged silica fume content in geopolymer results in increased compressive strength and enhanced thermal stability. However, an excessive silica fume content is detrimental to the generation of alkali-aluminosilicate gels and ceramic-like phases and thus exacerbates the high temperature damage.

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“…As both CCR and FA require no processing, the GWP (global warming potential) for this portion of CGF is considered to be zero [42,58]. Meanwhile, the GGBS is obtained through crushing and grinding, with a calculated GWP of 44 kgCO 2 e/t based on electricity consumption, while the cement's GWP is 940 kgCO 2 e/t.…”

Section: Quantitative Evaluation For Environmental and Economic Benefitsmentioning

confidence: 99%

Physical and Mechanical Properties of All-Solid-Waste-Based Binder-Modified Abandoned Marine Soft Soil

Liu,

Yang,

et al. 2024

JMSE

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Large quantities of abandoned marine soft soil are generated from coastal engineering which cannot be directly utilized for construction without modification. The utilization of traditional binders to modify abandoned marine soft soil yields materials with favorable mechanical properties and cost efficiency. However, the production of traditional binders like cement leads to environmental pollution. This study uses a CGF all-solid-waste binder (abbreviated as CGF) composed of industrial solid waste materials such as calcium carbide residue (CCR), ground granulated blast furnace slag (GGBS), and fly ash (FA), developed by our research team, for the modification of abandoned marine soft soil (referred to as modified soil). It is noteworthy that the marine soft soil utilized in this study was obtained from the coastal area of Jiaozhou Bay, Qingdao, China. Physical property tests, compaction tests, and unconfined compressive strength (UCS) tests were conducted on the modified soil. The investigation analyzed the effects of binder content, compaction delay time, and curing time on the physical, compaction, and mechanical properties of CGF-modified soil and cement-modified soil. Additionally, microscopic experimental results were integrated to elucidate the mechanical improvement mechanisms of CGF on abandoned marine soft soil. The results show that after modification with binders, the water content of abandoned marine soft soil significantly decreases due to both physical mixing and chemical reactions. With an increase in compaction delay time, the impact of chemical reactions on reducing water content gradually surpasses that of physical mixing, and the plasticity of the modified soil notably modifies. The addition of binders results in an increase in the optimum moisture content and a decrease in the maximum dry density of CGF-modified soil, while the optimum moisture content decreases and the maximum dry density increases for cement-modified soil. Moreover, with an increase in binder content, the compaction curve of CGF-modified soil gradually shifts downward and to the right, while for cement-modified soil, it shifts upward and to the left. Additionally, the maximum dry density of both CGF-modified and cement-modified soils shows a declining trend with the increase in compaction delay time, while the optimum moisture content of CGF-modified soil increases and that of cement-modified soil exhibits a slight decrease. The strength of compacted modified soil is determined by the initial moisture ratio, binder content, compaction delay time, and curing time. The process of CGF modification of marine soft soil in Jiaozhou Bay can be delineated into stages of modified soil formation, formation of compacted modified soil, and curing of compacted modified soil. The modification mechanisms primarily involve the alkali excitation reaction of CGF itself, pozzolanic reaction, ion-exchange reaction, and carbonization reaction. Through quantitative calculations, the carbon footprint and unit strength cost of CGF are both significantly lower than those of cement.

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Mechanical, microstructure and reaction process of calcium carbide slag-waste red brick powder based alkali-activated materials (CWAAMs)

Cited by 50 publications

References 44 publications

Study on the Properties and Hydration Mechanism of Calcium Carbide Residue-Based Low-Carbon Cementitious Materials

Study on the Properties and Hydration Mechanism of Calcium Carbide Residue-Based Low-Carbon Cementitious Materials

Synergistic Effect of Blended Precursors and Silica Fume on Strength and High Temperature Resistance of Geopolymer

Physical and Mechanical Properties of All-Solid-Waste-Based Binder-Modified Abandoned Marine Soft Soil

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