Modulation of the workability and Ca/Si/Al ratio of cement-metakaolin cementitious material system by using fly ash: Synergistic effect and hydration products

Wang, Shenyu; Gu, Xiaowei; Liu, Jianping; Zhu, Zhenguo; Wang, Hongyu; Ge, Xiaowei; Xu, Xiaochuan; Nehdi, Moncef L.

doi:10.1016/j.conbuildmat.2023.133300

Cited by 26 publications

(3 citation statements)

References 102 publications

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“…According to Chinese Standard GB/T 17671-2021 [47], the specimen size was determined as 40 mm × 40 mm × 40 mm; a picture of the plastic molds is shown in Figure 3. A constant-load compression testing machine was used for the 28 d age compressive strength test; the loading speed was 2.4 kN/s.…”

Section: Testing Methodsmentioning

confidence: 99%

Utilization of Copper–Molybdenum Tailings to Enhance the Compressive Strength of Alkali-Activated Slag-Fly Ash System

Wang,

Gu,

Wang

et al. 2024

Buildings

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Utilizing a variety of solid wastes to prepare alkali-activated cementitious materials is one of the principal trends in the development of cementitious materials. Commonly used alkali activation precursors such as granulated blast furnace slag (GBFS) and fly ash (FA) will be less available due to resource pressures. Supply limitation is an important reason to research alternative precursors. To realize the high value-added utilization of copper–molybdenum tailings (CMTs), this study adopted the modified sodium silicate solution as an alkaline activator to activate GBFS-FA-CMTs cementitious system to prepare alkali-activated cementitious materials. The influence of CMTs content on the compressive strength of GBFS-FA-CMTs cementitious system was analyzed, and the mechanism of GBFS-FA-CMTs cementitious system was also analyzed through hydration product types, physical phase composition, and microscopic morphology. The results indicated that a paste with the incorporation of CMTs, S50F30C20 (50% GBFS, 30% FA, 20% CMTs), achieved the highest compressive strength of 79.14 MPa, which was due to the filling effect of the CMTs and the degree of participation in the reaction. Pastes with different contents of CMTs, while maintaining a constant CBFS content, exhibited similar strength development. Excessive amounts of CMTs could result in reduced compressive strength. Microstructural analysis revealed that the hydration products were structurally altered by the addition of CMTs. In addition to ettringite, quartz, C(-N)-S-H gel, and calcite, gaylussite was also formed; moreover, the mass of chemically bound water increased, and the microstructure of reaction products became denser. An excess of CMTs may restrict the growth of the hydration gel, leading to more microstructural defects. The study suggests that CMTs could enhance the compressive strength of hardened paste within an alkali-activated slag-fly ash system, possibly due to a filling effect and participation in the chemical reaction. This research confirms the feasibility of using CMTs in alkali-activated cementitious materials.

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Section: Testing Methodsmentioning

confidence: 99%

Utilization of Copper–Molybdenum Tailings to Enhance the Compressive Strength of Alkali-Activated Slag-Fly Ash System

Wang,

Gu,

Wang

et al. 2024

Buildings

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“…Figure 2 shows that GGBS has a distinct hump, which indicates that it has a large amount of amorphous phases SiO 2 and Al 2 O 3 , whereas FA has a large amount of quartz and mullite, which makes them potentially water-hard, which is necessary for the preparation of gelling materials. In addition, FGDG particles, on the other hand, are prismatic dominated by monoclinic crystal system and have a more rough-hewn surface, whereas FA exists mostly in spherical structure [37], which not only acts as a roller ball to improve the fluidity and water retention of the gelling material [38], but also fills up the pores of the sample matrix [39,40].…”

Section: Raw Materialsmentioning

confidence: 99%

Experimental Study on the Properties and Hydration Mechanism of Gypsum-Based Composite Cementitious Materials

Liu,

Song,

et al. 2024

Buildings

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In order to achieve the resourceful, large-scale and high-value utilization of bulk industrial solid wastes such as flue gas desulfurization gypsum (FGDG), fly ash (FA) and ground blast furnace slag (GGBS), and to reduce the dosage of cementitious materials, orthogonal experimental methods were used to prepare composite cementitious materials based on the principle of synergistic coupling and reconstruction of multi-solid wastes. Through the method of extreme difference and ANOVA, the influence law of different factor levels on the performance of the cementitious materials was studied, and the maximum compressive strength of cementitious materials was reached when the ordinary Portland cement (OPC) dosage was 20%, the FGDG dosage was 56%, the FA dosage was 19.2% and the slag dosage was 4.8%, and the W/B was 0.55. The hydration products and microscopic morphology of the cementitious materials were analyzed by means of XRD, SEM and MIP techniques, so as to elucidate the complex synergistic hydration mechanism, and then to determine the more optimal group distribution ratio. The results show that the hydration reaction between FGDG and OPC can be synergistic with each other, and C-A-H further generates AFt under the action of SO42−, and at the same time, it plays the role of alkali-salt joint excitation for FA–GGBS, generates a large amount of cementitious materials, fills up the pores of the gypsum crystal structure, and forms a dense microstructure.

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“…It was found that fly ash and metakaolin improved compressive strength, reduced Ca/Si ratio, and promoted gel absorption in the Ordinary Portland cement (OPC)-Metakaolin (MK) system. The study also explored the feasibility of using fly ash to modify the OPC-MK system, examining its effects on cement properties and morphological features [29].…”

Section: Fig1 X-ray Fluorescence and Rietveld Quantitative Phase Anal...mentioning

confidence: 99%

Microstructural Analysis of Stabilized Rammed Earth Using XRD And SEM Methods

Fraz

2024

IJSREM

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The microstructure analysis of stabilized rammed earth (SRE) is crucial for understanding its mechanical properties, durability, and long-term performance. This literature review paper investigates the application of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) in analyzing the microstructural characteristics of SRE. XRD is employed to identify the crystalline phases present in the material, providing insights into the mineralogical composition and the effects of stabilization agents. SEM offers high-resolution images that reveal the surface morphology, particle distribution, and bonding mechanisms within the stabilized matrix. By synthesizing recent studies, this review highlights the advancements in microstructural analysis techniques and their implications for the optimization of SRE in construction. The findings from XRD and SEM analyses are integrated to present a comprehensive understanding of the microstructure-property relationships in SRE. The literature suggests that stabilization methods, such as the addition of cement, lime, or other additives, significantly influence the crystallinity, particle interlocking, and pore structure of the rammed earth. This review discusses the correlation between microstructural features observed through XRD and SEM and the resulting mechanical properties, such as compressive strength and durability. The paper concludes by identifying gaps in the current research and proposing directions for future studies, emphasizing the need for standardized testing protocols and the exploration of novel stabilization materials to enhance the performance of SRE. Keywords: X-Ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-Ray Analysis

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Modulation of the workability and Ca/Si/Al ratio of cement-metakaolin cementitious material system by using fly ash: Synergistic effect and hydration products

Cited by 26 publications

References 102 publications

Utilization of Copper–Molybdenum Tailings to Enhance the Compressive Strength of Alkali-Activated Slag-Fly Ash System

Utilization of Copper–Molybdenum Tailings to Enhance the Compressive Strength of Alkali-Activated Slag-Fly Ash System

Experimental Study on the Properties and Hydration Mechanism of Gypsum-Based Composite Cementitious Materials

Microstructural Analysis of Stabilized Rammed Earth Using XRD And SEM Methods

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