Cement Hydration Reaction Research Articles

Molecular modelling of cementitious materials: current progress and benefits

Developing new sustainable concrete technology has become an urgent need, requiring faster and deeper insights into the fundamental mechanisms driving the cement hydration reactions. Molecular simulations have the potential to provide such understanding since the hydration reaction and the cement chemistry are particularly dominated by mechanisms at the atomic scale. In this letter, we review the application of two major approaches namely classical (including reactive) molecular dynamics simulations and density function theory calculations of cementitious materials. We give an overview of molecular simulations involving the major mineral and hydrate phases.

Long-term ageing characteristics of cemented paste backfill: Usability of sand as a partial substitute of hazardous tailings

Considering environmental problems caused by sulfidic tailings as a result of long-term ageing as well as inadequacies in their gradations in ensuring the strength needed for cemented paste backfill (CPB), there is a need for viable and inexpensive solutions to eradicate these negativities caused by tailings. This study aims to boost long-term filling performance and lessen cement-related costs and environmental risks by using diverse proportions of sand as a partial substitute of tailings in CPB. For this purpose, rheological (mini slump), mechanical (e.g., UCS), microstructural (e.g., XRD, FTIR, SEM, and TG/DTG), and costs analyses of sand-based fills were investigated experimentally. Samples were prepared with a fixed solid content (70 wt%), five diverse replacement ratios (tailings/sand: 100/0, 90/10, 80/20, 70/30, and 60/40), and three diverse cement contents (3, 5, and 7 wt%), and then cured up to 180 days. Results showed that using sand as tailings substitution in CPB ameliorated its strength up to 3.22 MPa. This could be clarified by the fact that sand usage mends tailings gradation by improving its skeleton structure and forming a more compact material. Besides, owing to its high CaO content (∼54 wt%), sand contributes positively to hydration reactions of cement and prevents acid/leach formations that may occur in the long-term ageing. Lastly, it was concluded that sand increases CPB's performance and subsidizes sustainable mining/filling operations by falling the environmental impacts of hazardous tailings subjected to diverse disposal/curing conditions.

Experimental evaluation of temperature during setting of self compacting concrete

The cement hydration reaction is an exothermic reaction characterized by rise in temperature within the concrete during its setting phase. This is significant in the case of self-compacting concrete (SCC), having high cement content and low water-cement ratio. An experimental investigation was undertaken to measure the temperature developed during the setting of M-40 grade SCC mix. Two mixes of M-40 grade SCC with natural sand and crushed sand were investigated. Powder mix design was adopted for SCC mixes and fresh state properties were measured for both the mixes. 48-hour temperature data recorded with data logger systems were plotted for the two concrete mixes, along with ambient air temperature. The paper presents the findings from the experimental studies undertaken and attempts to infer the patterns of temperature variation observed during the setting of SCC mixes with natural sand and crushed sand.

Effect of Synthetic Ettringite on the Hydration of Sulfoaluminate Cement-Based Grouting Materials

Ultrafine ettringite (UE) can accelerate the hydration of sulfoaluminate cement-based grouting materials (SCGMs). However, the mechanism of UE on the hydration of SCGM is not clear. Many researchers believe that ultrafine materials can serve as crystal nuclei for hydration products. How to prove that UE can supply crystal nuclei for hydrated products remains an open question. It is still unclear for which SCGM hydration products UE can supply a crystal nuclei. In this article, UE was synthesized in different solvent compositions by a separate nucleation and growth step method. Synthetic UE was enclosed in a dialysis bag with a molecular weight cutoff of 7 kDa, which allowed the diffusion of water and ions, and the mechanism of UE’s effect on the hydration of SCGM was investigated. The results indicated that with the increase of the amount of ethanol in the water–alcohol mixed solvent, the particle size of the prepared UE gradually became smaller. UE only provided a nucleation site for ettringite, which was one of hydration products, and thus promoted a cement hydration reaction. The smaller the size of the UE, the higher the cement hydration rate and the greater the amount of hydration products produced.

Effect of lightweight sand and shrinkage reducing admixture on structural build-up and mechanical performance of UHPC

Pre-saturated lightweight sand (LWS) and shrinkage reducing admixture (SRA) can be used to mitigate autogenous shrinkage of ultra-high-performance concrete (UHPC). However, their individual and synergetic effects on structural build-up that is essential for thin bonded bridge deck overlay rehabilitation and 3D printing have not been well understood. This study investigates the impact of LWS and SRA on structural build-up of UHPC with mini-slump flow of 190 ± 10 mm. Furthermore, the cement hydration, autogenous shrinkage, mechanical performance, and porosity of UHPC prepared with LWS and SRA were studied. Test results show that the structural build-up enhanced from 90 to 138 Pa/min with the increase of the LWS content from 0 to 25% given the lower surface coverage ratio of high-range water reducer onto cement particles. The incorporation of 2% SRA led to the lowest structural build-up of 64 Pa/min due to the lower bridging effect of early-age hydration products. The LWS17&SRA1 mixture exhibited higher structural build-up of 105 Pa/min, lower autogenous shrinkage of 340 με, as well as comparable compressive strength, elastic modulus, and flexural strength of 139 MPa, 48 GPa, and 19 MPa compared to the Reference mixture prepared without any LWS and SRA that had the corresponding values of 90 Pa/min, 535 με, 142 MPa, 50 GPa and 19 MPa, respectively. The comparable mechanical performance was due to the increased effect of LWS on cement hydration and pozzolanic reaction of silica fume counteracted the reduced influence of SRA.

Amphoteric retarder for long-standing cementing: Preparation, properties and working mechanism

Amphoteric retarder (AIDA) was prepared by radical copolymerization of 2-acrylamido-2-methyl propane sulfonic acid (AMPS), itaconic acid (IA), 2-(Methacryloyloxy) ethyltrimethylammonium chloride (DMC) and methyl allyl polyethenoxy ether (TPEG). The characteristics of AIDA were verified by FTIR and 1HNMR. In addition, the performances of AIDA in cement slurry including thickening time, compressive strength developments, and adaptability to long standing cementing with lager temperature differences were investigated. The results indicated that AIDA possessed excellent temperature-resistance (180 °C) and good adaptability to long standing cementing with larger temperature differences of 90 °C. Finally, the retarding mechanism of AIDA was revealed through transverse relaxation time (T2) distribution, XRD tests, and adsorption behavior of AIDA on cement particles. The results demonstrated that the stronger retarding effect of AIDA originated from the dual adsorption of AIDA on cement particles compared with AMPS-IA copolymer (PAI). AIDA outperformed PAI in its adaptability to long-term cementing, which was responsible to (a): the adsorbed amount of AIDA at higher temperature is higher than that of lower temperatures, therefore, AIDA has a stronger retarding effect at higher temperature and weaker retarding effect at lower temperature. (b) Compared to PAI, the adsorption strength of AIDA is weaker and easy to de-adsorb, so both the retarding effect and the hydration reaction of cement are realized. Thus, the super-retarding phenomenon of cement slurry containing AIDA is effectively prevented.

Improved mechanical strength of magnesium oxysulfate cement using ferric sulfate

This research investigated the impact of ferric sulfate addition on the mechanical strength of magnesium oxysulfate (MOS) cement. Variations in the fluidity, setting time, hydration reaction, volume stability, water resistance, phase composition, and microstructure of MOS cement were reported. The results show that the addition of ferric sulfate accelerated the dissolution of MgO through reacting with OH− to form Fe(OH)3 gel and promoting the growth of 3 Mg(OH)2·MgSO4·8H2O, which reduced the fluidity and shortened the setting time of MOS cement. Although the growth time for 5 Mg(OH)2·MgSO4·7H2O was extended after adding ferric sulfate, the content and crystallinity of 5 Mg(OH)2·MgSO4·7H2O were increased, improving the mechanical strength and volume stability of MOS cement. The formation of Fe(OH)3 gel in MOS cement densified the matrix and optimized the pore structure, which can further enhance the mechanical strength and water resistance of MOS cement.

Dispersion and weak retardation performance of sulfate-based starch maleic acid monoesters in cement

To reduce the influence of a sulfate-based starch water-reducing agent on the setting time of cement, a novel starch-based water-reducing agent, namely sulfate-based starch maleic acid monoester (SAMAS), was designed to adjust its hydrophilicity by maleic acid monoester. Gel permeation chromatography, Fourier transform infrared spectroscopy, and 1H NMR nuclear magnetic resonance spectroscopy were used to characterize the prepared SAMAS, while Zeta potential, UV–Vis absorption, X-ray photoelectron spectroscopy, X-ray diffraction, cement paste fluidity, and setting time measurements were conducted to investigate its dispersion performance, retardation performance, adsorption behavior, and mechanism of action. SAMAS exhibited good dispersion performance and did not significantly prolong the setting time of the cement. In addition, the dispersion performance of SAMAS was found to depend mainly on steric hindrance, and its weak retardation performance originated from the hydrophilic regulation of the maleic acid monoester groups, which ensures the normal progress of the cement hydration reaction by hindering the formation of a hydration film.

Coupling mechanisms between cement hydration and permafrost during well construction in the Arctic region

During well construction in the Arctic region, the coupling mechanisms between cement hydration and permafrost may lead to unpredictable thaw of permafrost, thereby threatening the wellbore stability and ecological environment in the Arctic. In the present study, thermal kinetics of cement hydration under different temperatures are studied experimentally, and the hydration kinetics model is proposed. Then the coupled model is proposed considering the complicated physicochemical interactions between cement and permafrost. In the proposed model, the hydration reaction of cement, phase change of the permafrost, and the water migration in permafrost are considered. Moreover, the coupling mechanisms between cement and permafrost are studied by numerical simulations. Temporal and spatial distribution of properties in permafrost are obtained including the temperature, and the water/ice content. The obtained results shows an obvious temperature increase and permafrost thaw due to cement hydration heat. Moreover, it is found that low-temperature ambient in permafrost slows down the cement hydration process. During the permafrost thaw, dissociated water migrates from the warm area near the cement to the far cold area. Compared with the hydration process, heat diffusion in permafrost takes a much longer period. Thus, continuous attention should be paid to threaten posed by permafrost thaw for a long period after well cementing.

Mechanical Properties Enhancement of the Cement Mortar by Synthetic Zeolite Polymer Composites

The performance of cement mortar can be improved with additives based on waste by-products. Synthetic zeolite polymer composites (referred as SZPC) produced from the combination of solid waste ashes with a selective acrylic compound was used as a cement mortar additive. The effect of SZPC as an additive on hydration reaction of ordinary Portland cement (referred as OPC) at different amounts of SZPC, from 1-4% of OPC weight, as well as microstructure and mechanical behavior of the cement mortar are determined. The results from the hydration reaction rate test showed that the optimum amount of SZPC as the additive was 2% of OPC weight. Compressive strength and flexural strength of the cement mortar after 1, 7, 14 and 28 days of curing increased, with the largestincreases at the early stage. Additions of SZPC, synthesized by a waste by-product, improved mechanical behavior of cement mortars supporting sustainable development and the circular economy.

Exploring the Mechanical Properties, Shrinkage and Compensation Mechanism of Cement Stabilized Macadam-Steel Slag from Multiple Perspectives

Steel slag is characterized by high strength, good wear resistance and micro-expansion. This study aims at exploring the potential of steel slag in cement stabilized aggregates, mainly including mechanical properties, shrinkage and compensation mechanisms. For this purpose, the compressive strength and compressive resilient modulus of cement stabilized aggregates with different steel slag contents (CSMS) were initially investigated. Subsequently, the effects of steel slag and cement on dry shrinkage, temperature shrinkage, and total shrinkage were analyzed through a series of shrinkage test designs. Additionally, in combination with X-ray diffraction (XRD) and Scanning electron microscope (SEM), the characteristic peaks and microscopic images of cement, steel slag and cement-steel slag at different hydration ages were analyzed to identify the chemical substances causing the expansion volume of steel slag and reveal the compensation mechanism of CSMS. The results show that the introduction of 20% steel slag improved the mechanical properties of CSMS by 16.7%, reduced dry shrinkage by 21%, increased temperature shrinkage by 5.8% and reduced its total shrinkage by 19.2%. Compared with the hydration reaction of cement alone, the composite hydration reaction of steel slag with cement does not produce new hydrates. Furthermore, it is noteworthy that the volume expansion of the f-CaO hydration reaction in steel slag can compensate for the volume shrinkage of cement-stabilized macadam. This research can provide a solid theoretical basis for the application and promotion of steel slag in cement-stabilized macadam and reduce the possibility of shrinkage cracking.

Calculation of thermal state stress of the wind turbine’s foundation slab for the improvement of the quality and crack resistance

The thermal stress state of massive concrete and reinforced concrete structures during the construction period is characterized by the risk of large tensile stresses and, as a result, temperature cracks that violate the integrity of the structure. These defects are unacceptable for crack-resistant structures. The process of concrete hardening is accompanied by the release of a large amount of heat as a result of the hydration reaction of cement. The most dangerous cases are with uneven temperature distribution within the block body. Significant gradients can lead to stresses that exceed the stresses from operational loads. The thermal stress state is also influenced by temperature fluctuations of the surrounding environment, solar radiation, cooling rate of the block, initial and boundary conditions, and the possible cutting of a massive structure into separate concrete blocks. The latter factor is the subject of the research reflected in this study. The article establishes that, despite the possible increase in the construction time cutting the foundation plates into separate blocks by height can make the thermal stress state of the plate significantly more favorable in terms of ensuring crack resistance. In some cases, cutting can be such a successful method of combating temperature cracks that it will allow for the abandonment of special thermal insulation on the surface of the structure. The study shows the effectiveness of the cutting method depending on the number of blocks for the improvement of foundation slab quality.

Experimental Study on the Mechanical Properties of Green Lightweight Cement Composite Modified by Nano Additives

Abstract Cement materials have been commonly used in the building and construction industries. However, the process of cement manufacture has long been connected with high consumption of energy and adverse environmental impacts. In this study, in order to produce innovative green cement material that consumes lower energy, resources and is more eco-friendly, industrial waste by-product fly ash cenosphere (FAC) has been utilized as lightweight aggregate to replace cement by 73.3 %. Most research regarding lightweight cement materials with FAC has mainly paid attention to the influence of FAC and the reinforcement via fibre materials, but very few studies have been devoted to the incorporation of nano additives. Therefore, 0.05 %, 0.15 %, 0.45 % of carbon nanotubes (CNTs) and 0.2 %, and 1.0 % of nano silica (NS) were used to modify lightweight cement composite (LWCC). Experiments including flexural strength test, compressive strength test, and thermogravimetric analysis were performed to evaluate the mechanical behaviours and the hydration process of the produced LWCC. Based on the experimental outcomes, incorporating CNTs and NS can effectively contribute to enhancing both flexural and compressive strength, and facilitate cement hydration reaction.

Recycled aggregate seawater–sea sand concrete and its durability after immersion in seawater

Recycled coarse aggregate (RCA), seawater, and sea sand are sustainable and environmentally friendly materials that may be combined to make a new green building material. In this study, mineral admixtures were added to improve the properties of recycled aggregate–seawater–sea sand concrete (RASSC). The specimens were prepared with different replacement ratios of RCA, fly ash (FA), and silica fume (SF). The design compressive strength was set at C40 and optimized by orthogonal design. The durability of RASSC with the optimal mix proportion after immersion in artificial seawater at room temperature was studied in terms of axial compression performance, and flexural properties. The results showed that the compressive strength of RASSC with mineral admixtures could reach 47.8 MPa and that SF had the greatest influence, followed by RCA and FA. The continuous hydration and pozzolanic reaction of cement, FA and SF in the RASSC resulted in an increase in the axial compression performance and flexural properties at the initial stage of immersion. As the immersion time increased, chloride ions reacted with the cement product and formed Friedel salts, sulfate ions reacted with calcium hydroxide to form ettringite, gypsum and salt crystals, and the RASSC was more brittle with a poor ductility, resulting in the flexural failure mode changed from interface transition zone of recycled aggregate to recycled aggregate failure, fracture interface characterization results provided the evidence. The theory of plasticity was still applicable to RASSC, and the stress–strain relations was proposed.

Evaluation of pozzolanic reactivity of maize straw ash as a binder supplement in concrete

Cementitious materials, irrespective of their sources, play a vital role in cement hydration reaction in concrete. Hence, it is critical to understand how each supplement affects the early and later age properties of concrete. Maize Straw Ash (MSA), being a material with minimal consideration as a pozzolan for partial replacement of cement, was evaluated based on different researcher’s reports. A range of outcomes involving the use of maize straw ash as replacement materials in concrete were examined based on their impact on concrete in the early and later stages, and the findings were presented in addition to assisting in their future use. The impact of pozzolanic material on both mechanical and durability property were analysed, and how certain treatment methods influence the property of concrete in the early and later period. The data revealed that maize straw ash has comparable behaviour when given the same treatment technique before use, ability to increase strength over a long duration compared with other Agricultural waste (agro) materials, and likewise act as a void filler when concrete hardens to improve durability, with the usage of these materials for optimal strength not exceeding 20% replacement, shrinkage control not exceeding 30%, and 10–15% for good workability. At (500–800 °C calcination heat), the pozzolanic reaction produces good results.

The experimental investigation on the geo-polymerization of water-based filtercake at the second interface of the oil-gas well

The quality of bond along the second interface of sandstone oil-gas well is of an utmost important in order to ensure long-term zonal isolation throughout the lifecycle of the well by preventing the potential leakage of hydrocarbon fluids. Attaining effective long-term zonal isolation for the lifetime of oil-gas wells depends on the sealing capacity at second interface (SI). Existence of untreated filtercake at SI acts as weak point of potential leakage of hydrocarbon. Different techniques were developed to improve the situation; however, it is still difficult to cleaned up completely by chemical washes and spacers. Therefore, it is imperious to develop a method that can make a filtercake which can provide an effective bonding between the formation and the cement sheath. The experimental work introduces a novel KN solution developed in the laboratory, simulated wellbore as sandstone formation under the wellbore simulated conditions.The results revealed that the samples treated with KN solution had higher shear bond strength over untreated samples. The bond quality increased with the increase of curing time (3, 7, 14, and 28 days). The improvement was due to geopolymerization of remained water-based filtercake took place which led to formation of cementitious material such as Calcium-Silicate-Hydrate (C–S–H) and FTIR analysis revealed the formation of cementitious material (Calcium-Silicate-Hydrate (C–S–H)) and other geopolymers like Calcium-Aluminium-Silicate-Hydrate (C-A-S-H) and Sodium-Aluminium-Silicate-Hydrate (N-A-S-H)) along the interface which filled the existed pores hence reducing porosity hence high strength of bond at high concentration to treated samples. The untreated samples were observed at low transmittance revealing the low content of inorganic geopolymers hence poor bond quality. Thick water-based filtercake films at second interface, which prevented the complete reaction of cement hydration between rock grains and cement slurry material to form a chemical binder at the interface.This technique is of an utmost important as compared to the other means of improving shear bong strength. This chemical solution tends to convert the clay material into cementitious product (geopolymers) which will enhance the bonding strength. In addition, the formed products are high durable as it can withstand harsh environmental conditions such as higher elevated temperature and salinity condition hence leading to remedial cost reduction.

Study on mechanical properties and destabilization mechanism of unclassified tailings consolidation body under the action of dry-wet cycle

Tailings consolidation displacement technology is one of the ways to efficiently dispose of tailings waste and reduce tailings storage in surface tailings ponds. Unclassified tailings consolidation body (UTCB) under natural conditions is inevitably subjected to high temperature drying and rainfall wetting cycle changes (i.e. dry-wet cycle effect), which is the crucial factor affecting the stability of UTCB. The essence of destabilization damage of UTCB is an energy-driven crack progressive development process. This paper introduces the energy conservation theory and explores the destabilization mechanism of UTCB under the action of dry-wet cycles by combining macro mechanical parameters and meso structural characteristics. The results showed that as the number of dry-wet cycles increased, the mechanical parameters of UTCB at 3 and 7 d curing ages increased and then decreased. The pore size of the internal pores of UTCB matrix was dominated by micro-pores <10 nm. Increasing the number of dry-wet cycles caused the pore size to transform to 10–100, 100–1000 nm pore sizes. Moreover, at the initial period of the cycle (0–5th cycle), increasing the number of cycles induced the elastic energy curve to shift to the left, corresponding to the increased energy storage capacity of UTCB. At the later period of the cycle (10–15th), the elastic energy curve and energy storage level of UTCB showed the opposite trend. The dissipative energy and the energy difference (ek) curves better depicted the crack sprouting, expansion, propagation and convergence as well as energy storage, release, and dissipation processes of UTCB under the load. Dry-wet cycles induced a transition from shear failure to mixed tensile-shear failure after UTCB damage. At the initial period of the cycle, the surface layer of UTCB did not change significantly. At the later period of the cycle, the surface layer of UTCB was peeling off. There was a competitive relationship between cement hydration reaction, water erosion and temperature-induced particle expansion and contraction phenomena, which were the main factors causing changes in mechanical properties and energy storage of UTCB.

Properties and improvement of ultra-high performance concrete with coarse aggregates and polypropylene fibers after high-temperature damage

Ultra-high performance concrete containing coarse aggregates (UHPC-CA) is more cost-effective, with its low cost and easy access to materials, but its high-temperature performance and self-healing capability after post-fire curing remain to be further explored. In this paper, after high temperature, the compressive strength increases by approximately 20 MPa within 400 °C, and the micro-characteristics reveal that this is mainly because the temperature promotes the cement hydration reaction and pozzolanic reaction, which plays the role of secondary accelerated curing. Due to the continuous decomposition of substances, the flexural strength and ultrasonic pulse velocity gradually decrease; the mass loss, total porosity, and the amount of absorbed water increase, especially the sorptivity coefficient, which increases by more than 100 times after 800 °C. The residual values of all properties of UHPC-CA are best maintained by adding all of the finer PP fibers. Relying on many unhydrated gelling materials, UHPC has a more significant self-healing potential, improving its mechanical properties and permeability in all three post-fire curing environments. The most significant effect is seen in the water environment, where its recovery rate of strength exceeds 50 % in all cases. The self-healing enhancement of UHPC does not come from a single source, but from multiple combinations of physical and chemical reaction processes.

Effect of multilayer graphene oxide on the hydration and early mechanical strength of cement mortar in low temperature

The mechanical strength of cement mortar is normally decreased in a low-temperature environment, which is mainly due to the slow cement hydration reaction rate and an increase in the total pore volume, especially the harmful pore volume. With the modification of nano-materials, the early mechanical strength of cement-based materials can be effectively compensated. In this study, the effect of multilayer graphene oxide (MGO) on the early mechanical properties and microstructure of cement mortar at low temperatures of 0 °C, 5 °C, and 10 °C is studied by measuring the fluidity, setting time, mechanical property, scanning electron microscope (SEM), thermogravimetric (TG), and nitrogen adsorption/desorption test. Compared with the mechanical strength of control mortar with curing temperature of 20 °C, the mortars with the addition of MGO curing at low temperature present higher mechanical strength and denser microstructure. And the mechanism of the interaction between cement particles and MGO nano particles at low temperatures (0 °C, 5 °C, and 10 °C) is further discussed. The initial hydration reaction of MGO mortar is accelerated, which is mainly due to the nucleation effect of MGO and chemical reactions between –COOH on the edge of MGO nanosheets and the Ca2+ of Ca(OH)2. The promotion of the initial hydration refined the pore diameter of samples by reducing the pore size and total porosity, thus making the microstructure of samples denser and enhancing the strength of specimens.

Study on the Physical and Chemical Properties of Cement-Based Grout Containing Coal-Fly Ash.

To study the physical and chemical properties of grout containing fly ash, Class II fly ash was used as a mineral admixture and mixed with silicate cement to produce grout, and the rheological properties, strength properties, hydration properties, and microscopic mechanism were studied. The results of the study showed the following. The incorporation of fly ash reduced the thixotropic area of the composite cement slurry, which facilitated pumping in the pipeline conveying process. The inclusion of fly ash reduced the yield stress and plastic viscosity of the cement paste, but the rheological index increased and then decreased with the increase in fly ash, and the composite paste had the lowest degree of shear thinning at 30% fly ash inclusion. The incorporation of fly ash reduced the hydration exothermic rate and total hydration exothermic amount of the composite slurry and prolonged the hydration induction period, but the promotion effect of fly ash on the hydration rate of cement was obvious at 10% fly ash admixture. The admixture of fly ash increased the empty volume of the composite slurry, but the effect on the most probable aperture was not significant, and the porosity of the system increased, resulting in a decrease in compressive strength. The effect of adding fly ash on the hydration products was reflected mainly by the C-S-H gel produced by cement hydration and the change in calcium alumina and Ca(OH)2. Fly ash does not directly participate in the hydration reaction of cement, but it can promote cement hydration and increase the reaction rate of cement. By analyzing the rheological properties, mechanical properties, and hydration properties of fly ash composite cement paste, the comprehensive analysis found that the rheological properties are excellent when the fly ash admixture is 20-30%, and the water-cement ratio can be reduced to improve the strength without affecting the pumping demand.