Low Carbon Cementitious Materials Research Articles

A Review on Research Progress of Corrosion Resistance of Alkali-Activated Slag Cement Concrete.

China is the largest producer and user of Ordinary Silicate Cement (OPC), and rapid infrastructure development requires more sustainable building materials for concrete structures. Portland cement emits large amounts of CO2 in production. Given proposals for "carbon peaking and carbon neutralization", it is extremely important to study alternative low-carbon cementitious materials to reduce emissions. Alkali-activated slag (AAS) cement, a new green cementitious material, has high application potential. The chemical corrosion resistance of AAS concrete is important for ensuring durability and prolonging service life. This paper reviews the hydration mechanism of AAS concrete and discusses the composition of hydration products on this basis, examines the corrosion mechanism of AAS concrete in acid, sulfate, and seawater environments, and reviews the impact of its performance due to the corrosion of AAS concrete in different solutions. Further in-depth understanding of its impact on the performance of concrete can provide an important theoretical basis for its use in different environments and provides an important theoretical basis for the application of AAS concrete, so that we can have a certain understanding of the durability of AAS concrete.

The influences of MSWI fly ash washing and blast furnace slag/bottom ash ratio on low-carbon cementitious materials

The heavy metal and soluble salt content in municipal solid waste incineration fly ash (MSWI FA) negatively affects the leaching safety of cementitious material, thereby impacting their corrosion resistance and durability. In this study, an MSWI FA washing pretreatment was conducted to obtain WFA1, and a low-carbon, low-cost cementitious material (FBM) was prepared in combination with bottom ash (BA). The optimal ratio parameters determined through orthogonal experiments were a mass ratio of 51% blast furnace slag (BFS), 17% BA, 20% WFA1, and 12% flue gas desulfurized gypsum (FGDG). The FBM containing WFA1 exhibited strong macroscopic performance, with a compressive strength of 37.42 MPa for FB2 at 28 days. The leaching concentrations of Pb, Zn, As, and Cd met the standards for underground Class II water quality. The leaching concentrations of Cl− and SO42− were in the ranges of 90–200 mg/L and 20–100 mg/L, respectively. The reduction in the BFS/BA ratio led to decreased polymerization degree (RBO = 0.310) and chain length (MCL = 2.627) of C–(A)–S–H gel, along with a decrease in Al [VI] content in ettringite (22.63%). Furthermore, Cl− played a stronger role than SO42− in the generation of Friedel's salt. The economic benefit of producing one ton of FB2 was calculated to be 38.60 USD, with CO2 emission of only 10.97 kg. The ultimate aim of this study was for waste-generating enterprises to achieve internal synergy in the disposal of solid and hazardous waste, thereby creating a “zero-waste company and group."

Evaluation of long-term aging of low-carbon cementitious materials under severe H2S impact in sewerage systems

The durability of cementitious materials in harsh environments, like marine or sulfate-rich soils, is influenced by various factors, with bacteria playing a significant role alongside environmental chemistry. To address sustainability concerns, research focuses on developing cement mixes that reduce emissions and withstand aggressive conditions. New standards require testing these mixes. This study developed and tested low-carbon cement mixes (CEM III, CEM V, CAC, and CSS) under real sewer conditions enriched with H2S and bacteria for four years. The specimens underwent SEM-EDS, XRD, TGA-DTA, and µRaman analysis to enhance understanding of degradation processes by conducting detailed and localized characterization of both initial and newly formed phases. Through this analysis, the work offers a precise description of the effects of bio-alteration on various cement matrices, elucidating their reactions under such conditions. The analysis of mortar specimens has revealed the presence of expansive products such as gypsum besides various polymorphs of calcium carbonate.

Hydration and microstructure formation of magnesium oxysulfate (MOS) cement regulated by sepiolite with high adsorption ability

Magnesium oxysulfate (MOS) cement is a potential low-carbon cementitious material with its characteristic depending on the reaction between light-burned magnesia (LBM) and MgSO4 solution. This work aimed to elucidate the effect of sepiolite with high adsorption ability on regulating the reaction within MOS cement. Replacement levels of LBM by sepiolite at 2 and 5 wt% were adopted. Hydration kinetics, microstructure, phase composition and compressive strength of MOS cement without and with sepiolite were studied. Results showed that adding sepiolite into MOS cement adjusted the ion distribution at the early hydration stage and promoted the reaction with an early onset of heat flow peaks. The presence of sepiolite refined the morphology of formed needle-like 5 Mg(OH)2·MgSO4·7H2O (517 phase) and strengthened the bond water within its structure. The high adsorption ability of sepiolite enabled the nucleation of 517 phase and amorphous phase onto its surface. Sepiolite also densified the poorly hydrated regions by tightly combining with the incompletely hydrated MgO grains. Consequently, compressive strength of MOS cement under air curing was improved after adding sepiolite.

Improvement of strength and microstructure of low-carbon cementitious materials with high volume of calcined coal gangue

The accumulation of coal gangue poses significant environmental challenges due to its massive volume and low reactivity. This study investigates the influence of calcium hydroxide (Ca(OH)₂) and gypsum on the mechanical properties, hydration, and pore structure of low-carbon cementitious materials incorporating high volumes of calcined coal gangue (CCG) and limestone. The results showed that the addition of Ca(OH)₂ significantly increased compressive strength, with a 19 % improvement at 28 days in LCC-40-P mix, which contained 40 % cement and 2.73 % Ca(OH)₂ by weight. The incorporation of 10 % gypsum in the LCC-40-P mix and 20 % gypsum in the LCC-70 mix (containing 70 % cement without Ca(OH)₂) effectively refined the pore structure, reduced overall porosity, and enhanced the material's density and mechanical properties, resulting in compressive strengths of 38.4 MPa (72 % of the strength of Portland cement) and 50.2 MPa (94 % of the strength of Portland cement) at 28 days, respectively. Microstructure and hydration heat tests showed that the addition of Ca(OH)₂ accelerates the hydration reaction and significantly enhanced compressive strength by ensuring sufficient Ca(OH)₂ for pozzolanic reactions, leading to the formation of additional calcium silicate hydrate, calcium aluminate silicate hydrate and carboaluminate phases. Gypsum refined the pore structure by shifting the pore size distribution towards smaller sizes, reducing overall porosity, and increasing the proportion of gel and small capillary pores. These findings highlight the potential of using CCG with optimized additives to develop sustainable, low-carbon construction materials with enhanced performance characteristics.

Resource utilization of sulfidic copper tailings in calcium aluminate cement: Mechanical property, hydration process and environmental impact

Sulfidic copper tailings (STs) is a byproduct generated from mineral processing activities. To address this environmental burden, calcium aluminate cement (CAC) was used to utilize STs as cementitious materials. The influence of STs on the hydration process, mechanical properties and life-cycle assessment of STs blended CAC were investigated. Results show that the initial setting time of the samples is significantly shortened with the presence of STs. Moreover, the addition of STs greatly accelerates cement hydration and promotes the formation of ettringite, which is caused by the dissolution of sulfidic-rich STs. Hence, the hardened cement paste containing 5 wt.% STs with dense microstructure and high elastic modulus is achieved, which enhances the compressive strength for STs blended CAC. From an environmental point of view, the utilization of STs can save energy and reduce CO2 emissions. Such work may provide new insights into the application of sulfidic copper tailings in low-carbon cementitious materials.

Insight into the performance of composite binder with high-volume steel slag, blast furnace slag and desulfurization gypsum

The performance of composite binders with high-volume steel slag (SS), granulated blast furnace slag (GBFS) and desulfurization gypsum (DG) were systematically investigated. The results show that the synergistic effects of high volume (40–60%) of SS with GBFS and less than 15% of DG could perform adequate setting time, higher strength, well volume stability and soundness as well as dense microstructure. The higher compressive strengths exceeding 70 MPa at 28 days and up to 80 MPa at 90 days could be obtained for composite pastes with high-volume SS, which exhibit tight relationships with [CaO]·[SO3]/[Al2O3]·[SiO2] and [CaO]·[Al2O3]/[SO3]2 molar ratios. More (15–19%) AFt and less (about 1%) portlandite produced during the hydration of composite binders. C–S–H gels and calcite crystals were formed. The composite binder possesses lower energy consumption, high carbon reduction and low cost compared with Portland cement in favor of the low-carbon cementitious material production and effective utilization of SS.

Study on the Effect of Water–Binder Ratio on the Carbonation Resistance of Raw Sea Sand Alkali-Activated Slag Concrete and the Distribution of Chloride Ions after Carbonation

The excessive extraction of river sand has led to significant ecological issues. Moreover, the environmental impact and resource demand of cement production have increasingly turned the spotlight on sea sand as a viable alternative due to its abundance and ease of extraction. Concurrently, alkali-activated binders, a novel type of low-carbon cementitious material, have gained attention for their low energy consumption, high durability, and effective chloride ion fixation capabilities. However, they are susceptible to carbonation. Introducing a controlled sea sand amount can raise the materials’ carbonation resistance, although carbonation may raise the concentration of free Cl− within the structure to levels that could risk the integrity of steel reinforcements by accelerating corrosion. In this context, the current study investigates sea sand alkali-activated slag (SSAS) concrete prepared with varying water–binder (W/B) ratios to evaluate its impact on flowability, mechanical strength, performances, and chloride ion distribution post-carbonation. The results demonstrate that the mechanical property of SSAS concrete diminishes as the water-to-binder ratio increases, with a more pronounced reduction observed. The depth of carbonation in mortar specimens also rises with the W/B ratio, whereas the compressive strength post-carbonation initially decreases before showing an increase as carbonation progresses. Furthermore, carbonation redistributes chloride ions in SSAS, leading to a peak Cl− concentration near the carbonation front. However, this peak amplitude does not show a clear correlation with changes in the W/B ratio. This study provides a theoretical foundation for employing sea sand and alkali-activated concrete.

Study on the design method of multi-component industrial solid waste low carbon cementitious material with cement as the activator

The relationship between microstructure and mechanical properties of multi-component solid waste low-carbon cementitious materials has been widely pay attention to. However, industrial solid waste is a complex multi-component system with many variable factors, which makes it difficult to design the formulation of cementitious materials. This paper pioneered the application of machine learning (ML) models, algorithms and error rates to analyze the compressive and flexural strength of fly ash-based pastes. Coefficient of determination (R2), mean squared error (MSE), root mean square error (RMSE), mean absolute error (MAE) and a20-index were used to evaluate robustness. X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Taylor (BET) were carried out to analyze evolution of cementitious materials. The evaluation results of ML models exhibited that the Gradient boosting regression (GBR) model had the best determination parameters and a steep normal distribution fitting curve with an a20-index of 0.861. GBR model exhibited the best robustness. The key factors of fly ash-based cementitious materials were identified by Pearson's coefficient, which was benefit to determine the formulation of multi-component solid waste low-carbon cementitious materials. Furthermore, experiments also demonstrated that the optimum ratio of multi-component solid waste low carbon cementitious material was 10 % gypsum, 10 % metakaolin, 45 % fly ash, 15 % slag and 20 % cement, respectively. It was worth noting that the compressive strength of this kind of multi-component solid waste low-carbon cementitious materials reached 35 MPa, which was superior to the mechanical properties of P·O 32.5 cement. The results of phase, SEM images and pore structure distribution showed that the synergistic effect of the multi-component solid waste materials effectively filled the material voids and also facilitated the formation of a variety of gelatinous materials through gelling reactions in the late stage (14–28 d). This work will promote the resource utilization of industrial solid waste, contribute to carbon reduction, and can accelerate the green revolution of concrete.

The research on the mechanical properties, microstructure, environmental impacts of environmentally friendly Alkali-activated ultra high performance concrete (AAUHPC) matrix with varied design parameters

Alkali-activated material prepared by the silicon aluminum solid wastes are commonly considered as the low-carbon cementitious material, which has important significance for promoting the sustainable development of construction materials. The mechanical properties, reaction mechanisms, and microstructure evolutions of Alkali-activated Ultra High Performance Concrete (AAUHPC) matrix with 7 design parameters were comprehensively studied through testing the fluidity, 28 days compressive strength, 28 days flexural strength, hydration heat, and microstructures. The environmental impacts including carbon emissions and energy consumption are evaluated. Appropriately increasing Na2O dosage, silicate modulus (Ms), and granulated blast furnace slag (GBFS) to fly ash (FA) mass ratio (GBFS/FA) and decreasing silica fume (SF) content and water to binder ratio (W/B) are conducive to accelerating the early reaction of AAUHPC. High Na2O dosage, Ms, SF content, and W/B are not conducive to increasing the 3 days reaction degree of AAUHPC, while the moderate GBFS/FA is corresponding to the higher 3 days reaction degree of AAUHPC. The optimal Na2O dosage, Ms, GBFS/FA, SF content, sand to binder ratio (S/B), fine sands content in quartz sands, W/B are 8 %, 1.4, 4.5:1, 10 %, 1.0, 50 %, and 0.34 for the 28 days mechanical properties. The acquired AAUHPC matrix with fluidity of 218 mm and the lowest porosity has 28 days compressive strength of 114.8 MPa and 28 days flexural strength of 10.6 MPa, whose microstructure has more high polymerization degree C(N)-A-S-H gels with higher Al/Si, lower Na/Al, and lower Ca/Si molar ratios. Compared to the traditional Ultra High Performance Concrete (UHPC), the environmentally friendly AAUHPC can reduce the carbon emission by 42%–52 % and the energy consumption by 5%–18 %. The total CO2 emission of per unit compressive strength (1.0 MPa) of concrete per cubic meter (CI) is in range of 2.5–3.7 kg, which is significantly lower than the traditional UHPC (6.98 kg/MPa•m3).

Mechanical properties and hydration mechanism of low carbon concrete with recycled aggregate

Collaborative and effective disposal of construction and industrial solid waste is of great significance for protecting the ecological environment. In this paper, low carbon concrete with recycle aggregate (LCCRA) mainly made of phosphogypsum, fly ash, slag and recycled aggregate was studied. The uniaxial compression test was carried out to determine the stress-strain relationship of LCCRA and a constitutive model for LCCRA under uniaxial compressive loading was established. Scanning Electron Microscopy (SEM) was used to explore the hydration process of LCCRA. The results demonstrated that the uniaxial compressive strength of LCCRA achieved 30.8 MPa with a 100 % replacement rate of recycled coarse aggregate and a water-binder ratio of 0.54. The constitutive model of LCCRA under uniaxial compression fits well with the experimentally measured stress-strain curve. SO42− in low carbon cementitious materials reacts with [SiO4]4-, [AlO4]5- to generate C–S–H gel, C-A-S-H gel and AFt crystals, which enhance the density of LCCRA interfacial transition zone (ITZ) and thus improve its basic mechanical properties.

Mechanical properties and electromagnetic wave absorption characteristics of solid waste low-carbon cementitious materials

A low-carbon multi-functional cement substitute material has been developed to reduce electromagnetic pollution in building spaces and protect human health. The solid waste electromagnetic absorption cementitious material (SWEACM) is produced by combining steel slag (SS), blast furnace slag (BFS), and phosphogypsum (PG). In this study, the properties of SWEACM were analyzed, including flow, electromagnetic wave absorption, strength, and environmental properties. Additionally, the hydration and electromagnetic wave absorption mechanisms were examined. The results indicate that SS, BFS, and PG content significantly affect the strength and electromagnetic wave absorption properties of SWEACM. S-6 exhibits the best overall performance (SS: BFS: PG = 3:6:1), with the highest strength (28 days compressive strength = 33.5 MPa) and fluidity (19.1 cm). Furthermore, it has excellent electromagnetic absorption performance (RLmin = −45.4 dB), with an adequate absorption bandwidth of up to 10 GHz in the 2–18 GHz range. The excellent electromagnetic wave absorption capability of SWEACM is mainly due to the resonance, polarization relaxation loss, and conduction loss of the magnetic and conductive components in the material. The results show that SWEACM can be used as a multi-functional construction engineering material for electromagnetic protection, combining high levels of high electromagnetic wave absorption, strength performance, and environmental benefits.

A low-carbon cement based on silicomanganese slag and granulated blast furnace slag: Hydration process, microstructure, mechanical properties and leaching risks

The calcium content of silicomanganese slag is only about 50 % of that in granulated blast furnace slag but the manganese content is high (>10 wt%), which limits the wide application of silicomanganese slag in cementitious materials. The present study provides a low-carbon cementitious material with an above-average silicomanganese slag content, which provides a new method for the recycling of silicomanganese slag and other solid wastes. The mechanical properties, hydration mechanisms, and pore structures of low-carbon cementitious materials with different silicomanganese slag and granulated blast furnace slag ratios were investigated using carbide slag as alkali-activator and flue gas desulfurization gypsum as sulfate-activator. The feasibility of silicomanganese slag as a significant replacement for granulated blast furnace slag in cementitious materials was explored, and the risk of manganese leaching was assessed. Silicomanganese slag has slower hydration rate in the early stage, but the reaction accelerates in a later stage and the gap with granulated blast furnace slag decreases. The 3, 7, and 28-d compressive strengths of mortars consisting of 40 % silicomanganese slag, 40 % granulated blast furnace slag, 12 % flue gas desulfurization gypsum, and 8 % carbide slag reached 28.7, 41.2, and 49.9 MPa, respectively. When the silicomanganese slag content is 80 %, the leaching toxicity test results showed ≤0.1 mg/L, and jouravskite was present in the hydration products, which indicated a low risk of manganese leaching in normal service environments.

Rheological behavior and early-age hydration performance of blended cement pastes incorporating recycled brick powder and slag

This study focuses on blended cement pastes incorporating recycled brick powder (RBP) and slag. The effects of RBP and slag on the rheological behavior and early-age hydration performance of blended cement pastes with different substitution levels ranging from 0 % to 40 % have been studied by testing mini-slump flow, rheological properties, hydration products, pore structure, and phase distribution. The results show that the incorporation of RBP reduces the fluidity by 3.8 %-24.6 % and increases the yield stress of pastes by 4.1 %-53.4 %, while the combined use of RBP and slag proves effective in controlling the rheological properties. Furthermore, the addition of RBP and slag significantly reduces the hydration products and increases the total porosity of blended cement pastes by 4.3 %-16.9 % at 24 h. Notably, RBP and slag accelerate Portland cement hydration in early-age stage, attributed to nucleation and dilution effects. These findings offer valuable insights for the application of RBP in low-carbon cementitious materials.

Strength evolution and microstructure of alkali-activated ultra-fine slag in low-temperature environments

At low temperatures, the hydration rate of Portland cement significantly slows down, resulting in a decrease in its strength. Additionally, the pore solution freezes easily. As a kind of low-carbon cementitious material, alkali-activated slag (AAS) material has a short setting time at room temperature and a high early strength, meanwhile the alkali solution does not freeze at low temperatures. This study investigates the evolution mechanism of the strength and microstructure of AAS pastes cured at 0℃. Slag with different fineness was activated by a sodium silicate solution with different moduli, whose strength was compared with that of an AAS paste cured at 20 °C. The setting time, compressive strength, hydration process, pore structure, freezing point, and microstructure of the AAS paste were studied, whose results showed that the setting time of the AAS paste was obviously prolonged, and the compressive strength decreased under low-temperature curing. After the activation of slag ground, the early compressive strength of the AAS paste was significantly improved, whose reason was that the hydration degree of the paste was improved after slag ground, and that a dense pore structure was formed. The freezing point of the AAS paste was approximately −26 °C, which, remarkably, even at −40 °C, was still capable of undergoing a weak chemical reaction, producing an exothermic enthalpy. This characteristic makes alkali-activated ultrafine slag a highiy-promising cementitious material for curing at low temperatures.

Study on the Alkali–Sulfur Co-Activation and Mechanical Properties of Low-Carbon Cementitious Composite Materials Based on Electrolytic Manganese Residue, Carbide Slag, and Granulated Blast-Furnace Slag

Industrial solid waste is characterized by complex mineral phases and various components. Low-carbon cementitious materials can be prepared through precise regulation based on the material composition and properties of various industrial solid wastes. In this study, electrolytic manganese residue (EMR), carbide slag (CS), and granulated blast-furnace slag (GBFS) were used as alternatives to cement to prepare multicomponent solid waste cementitious materials. The effects of the proportions of EMR and CS on the cementitious activity of GBFS and the activation mechanism of alkali and sulfur were studied. The results showed that with increasing EMR content, the strength first increased and then decreased. At a GBFS content of 20%, CS content of 2%, and EMR content of 8%, the compressive strength was highest, reaching 45.5 MPa after 28 days of curing, mainly because the OH− in CS and SO42− in EMR synergistically stimulated the active components in GBFS. Hydrated products such as ettringite and hydrated calcium silicate (C–S–H gel) were generated and interlaced with each other to improve the densification of the mortar. Overall, the proposed system provides an avenue to reduce or replace the production of cement clinker and achieve the high-value-added utilization of industrial solid waste.

Influence of raw material properties on microscopic and mechanical characteristics of alkali-activated materials

Alkali-activated fly ash and slag pastes are considered a new low-carbon cementitious material with good mechanical characteristics and durability. However, the mechanical characteristics of the alkali-activated materials are uncertain due to the multiplicity of the raw material properties. Few studies clarify how the raw material properties affect the mechanical characteristics of hardened pastes. The correlation between the raw material properties and the reaction rate, product composition, gel content, and pore size distribution is discussed in this study. The increase in the CaO content of the precursor will accelerate the degree of alkali activation. In this case, the reaction production becomes relatively more, and the pore size distribution becomes relatively denser, improving the compressive strength of the pastes. Moreover, the effects of the activator modulus and alkali content on the compressive strength of the pastes are not monotonically increasing. The excessive alkali will cause the surface of raw material particles to form a gel layer quickly, which could prevent the further alkali activation of the particles. This case is not conducive to gel formation and will cause the pore structure of the hardening pastes to be relatively loose. Furthermore, the influence of activator modulus on the compressive strength of pastes is lower than that of alkali content. Excess activator modulus is also unfavourable for pore structure densification.

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

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.

Formulation optimization of oil shale semi-coke/lime/cement solidified loess based on ternary nephogram and establishment of elastic-plastic damage model

Oil shale semi-coke (OSS) is a industrial solid waste produced after the dry distillation refining of oil shale. Due to its internal enrichment of activity silico-aluminate minerals, it can be utilized to prepare low-carbon cementitious materials through alkali activation. In this study, a composite material for reinforcing loess was synthesized using OSS, lime, and cement. Drawing upon the ternary design method, the optimization of oil shale semi-coke/lime/cement stabilized loess (OLC-SL) formulation was explored. Through microscopic analysis, the enhancement mechanism of OLC-SL was probed. Furthermore, it comprehensively understood the stress-strain characteristics of OLC-SL by conducting triaxial experiments and developed an elastic-plastic damage model for OLC-SL through numerical. The outcomes of this study provide novel insights and theoretical support for the resource utilization of OSS waste, and hold crucial implications for promoting the large-scale application of OSS waste in the disposal of expansive loess.

Improvement of the mechanical properties of beta-hemihydrate phosphogypsum by incorporating wet-ground low-calcium fly ash slurries

Beta-hemihydrate phosphogypsum (β-HPG) is a low-carbon cementitious material used in construction. Nevertheless, the poor water resistance and low mechanical strength of β-HPG limit its utilization. In this study, two low-calcium fly ash (FA) slurries with median particle sizes of 1.83 μm and 1.14 μm were prepared using a wet-grinding process for the improvement of β-HPG, and the mechanical strength and softening coefficient were tested to assess the effect. The results show that wet-ground low-calcium FA can significantly enhance the mechanical strength and softening coefficient of β-HPG. Compared with specimens without wet-ground low-calcium FA, the dry compressive strength and softening coefficient of specimens with 30% wet-ground low-calcium FA (D50=1.14 μm) increased by 104.9% and 71.8%, respectively. It is worth noting that the 1 d compressive strength also increased by 11.9%. Specifically, wet-ground low-calcium can increase the pH value and conductivity of the FA slurry, further accelerate the hydration process of FA in β-HPG, forming more ettringite and gels to fill in the pores between dihydrate gypsum (DH) crystal, and reducing the larger pores in the hardened paste. This study can develop a high-performance cementitious material that will enable the effective use of β-HPG.