Water Requirement Of Normal Consistency Research Articles

Effects of Dosing and Mechanical Activation on the Performance of Reservoir Sediment-Cement Composite Cementitious Material

To solve the problem of reservoir sediment accumulation, this paper intends to study the feasibility of preparing reservoir sediment-cement composite cementitious material by partially replacing cement with reservoir sediment. Using the single factor test method, the replacement rate of reservoir sediment and mechanical activation time were selected as variables to explore the effects of water requirement of normal consistency, setting time, mortar fluidity, and mechanical properties of mortar specimens. The results show that with the increase of sediment replacement rate, the water requirement of normal consistency of composite cementitious material paste increases, the setting time increases, the fluidity of mortar decreases, and the mechanical properties of mortar specimens decrease significantly. With the increase of mechanical activation time, the water requirement of normal consistency decreases, the setting time decreases, the fluidity of mortar increases, and the mechanical properties of the mortar specimen increase. The microcosmic results show that mechanical activation can promote the formation of C-S-H gel in reservoir sediment, and fill each other with unreacted reservoir sediment particles, resulting in a denser microstructure. The purpose of this paper is to provide theoretical support for the preparation of reservoir mud-cement composite cementitious material.

The potential of copper slag as a precursor for partially substituting blast furnace slag to prepare alkali-activated materials

The safe and efficient treatment of copper slag (CS) is an important aspect of the circular economy and green development. In order to reduce the negative environmental impact, CS is used as a precursor to substitute different contents of ground granulated blast furnace slag (GGBS) in the manufacturing of alkali-activated materials (AAM)) in this study. The feasibility of AAM incorporated with CS as a precursor is evaluated through the macroscopic performances including setting time, water requirement of normal consistency (WRNC), fluidity, compressive strength and flexural strength. Additionally, the microstructure is characterized using nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA), respectively. The results show that the optimal substitution rate of CS for GGBS in AAM mortar is 30 wt%. The compressive strength and flexural strength of AAM incorporated with 30 wt% CS at 28 days reach 71.7 MPa and 9.3 MPa, respectively, which are equivalent to the control group. The microstructure analyses reveal that the substitution of GGBS with CS reduces the formation of C-A-S-H due to the relatively low pozzolanic activity of CS. However, the micro-aggregates effect of CS and the filling effect of its hydration products (ferric hydroxide/ferrous hydroxide, and ferrosialate gels) can enhance the compactness of hardened paste and improve its mechanical performance.

Relationship between the evolution of organic impurities and properties of β-hemihydrate phosphogypsum

Transforming phosphogypsum (PG) into β-hemihydrate gypsum plasters is one of the most effective and high-value-added pathways to consume and utilize PG. However, the relationship between the evolution of organic impurities and the properties of gypsum plaster is still unclear. In this paper, the composition and evolution of organic impurities, including pure organic matter (PO) by flotation and polyacrylamide (PA), were characterized, and their influence on the dehydrate behavior of PG and water requirement for normal consistency, setting time, mechanical strength, microstructure, and appearance of gypsum plasters at the calcination temperature of 150 °C and 200 °C were explored. The results showed that at 150 °C, PA and PO could increase the water requirement for normal and setting time of gypsum plaster and reduce the mechanical strength due to the reduced wettability and bonding strength causing by their intact structure and covering on HPG surface. At 200 °C, decomposed products of PO containing P-O-P and OH- groups could interact with Ca2+ and inhibit the dissolution of hemihydrate gypsum, resulting in coarsened crystals, thereby reducing the compressive strength. PA could partially decompose into the micro-molecular polymer and cover on the hydration products, leading to an increased densification compared to 150 °C. Besides, organic impurities could cause blackening, spots, and mildew on the gypsum plaster surface.

Effect of ultrafine recycled brick powder on the properties of blended cement: Hydration kinetics, microstructure evolution and properties development

Ultrafine grinding is expected to be an effective method to increase the pozzolanic activity of RBP, since RBP has superior grindability. The aim of this paper was to investigate the effects of 30 % ultrafine RBP with particle size of 8.6 μm, 4.5 μm, 3.6 μm and 2.7 μm on the fundamental properties, hydration kinetics and microstructure evolution of blended cement. The setting times, water requirement for normal consistency, rheological properties, hydration heat, hydration degree, mechanical strength and pore structure of cementitious material were evaluated. Results show that when 30 % RBP was added, the water requirement and viscosity of blended cement increased significantly with the decrease of RBP particle size, while the setting time was shortened due to the acceleration of early-age cement hydration. The parameters for the Boundary Nucleation and Growth (BNG) model indicate that the nucleation and growth rates of hydration products increased by 1.43 times and 1.27 times when RBP with D50 = 2.7 μm was added, thus the cement hydration degree reached more than 50 % in the first 72 h. Based on the thermogravimetric analysis (TGA), the pozzolanic reaction degree of ultrafine RBPs was more than 15 %–25 % depending on its size, and the hydration degree of cement in RBP-PC pastes was more than 80 %. As a result, blended cement mortars with up to 30 % ultrafine RBPs has slight or even no strength loss after curing for 90 days, as RBP-PC paste has a denser microstructure.

Preparation and curing method of red mud-calcium carbide slag synergistically activated fly ash-ground granulated blast furnace slag based eco-friendly geopolymer

The commercial alkali activators could account for more than 50% of the cost for producing geopolymers. Thus, to lower the carbon footprint of geopolymer by avoiding the utilization of energy-intensive commercial alkali activators, a novel eco-friendly geopolymer was synthesized from 100% solid wastes comprising red mud (RM), calcium carbide slag (CS), ground granulated blast furnace slag (GGBS) and fly ash (FA) in this study. Effects of GGBS contents and curing conditions on the compressive strength, fluidity and water requirement for normal consistency were investigated. The hydration products in the binders cured at different conditions were characterized by X-ray diffraction (XRD), thermogravimetric (TG), Fourier transformation infrared spectroscopy (FTIR) and scanning electronic microscopy (SEM). The results showed that GGBS improves the compressive strength as well as the mortar fluidity and reduces the water requirement for normal consistency of the geopolymer. Raising the curing temperature up to 60 °C and prolonging the heat curing duration to 12 h facilitate the dissolution and polymerisation of the FA-GGBS and therefore increase the amount of gel and crystalline products, whereas excessive heat-curing at temperatures higher than 60 °C and durations longer than 12 h causes shrinkage cracks at later age, which was detrimental to the compressive strength. The mineralogical characterization revealed that the amount of gel governs the strength development and heat curing favors the formation of secondary crystalline phase hydrotalcite. The developed binder can be used to produce low-carbon clinker-free concrete blocks to improve the sustainability of concrete industry.

Effect of biochar from municipal solid waste on mechanical and freeze–thaw properties of concrete

Global municipal solid waste (MSW) generation and cement manufacture pose catastrophic threats to the environment. Although positive impacts have been demonstrated for biochar originating from single biomass in concrete, limited studies focused on the biochar from the pyrolysis of municipal solid waste, and the freeze–thaw resistance of biochar concrete still remains unknown. This paper explored the feasibility of biochar derived from MSW at 600℃ to replace 1%-30% cement by weight in concrete. Properties of water absorption, setting time, mechanical properties and freeze–thaw resistance for the mixture systems were studied with the inspections of Scanning electron microscope (SEM), Fourier transforms infrared spectrometer (FT-IR) and X-ray diffraction (XRD). The results suggested that biochar replacement reduced the setting time of the binder system with an increase in water requirement of normal consistency. The compressive strength of concrete was increased by 9.2% with less than 5% of cement replaced. Biochar markedly improved the flexural and splitting tensile strength of concrete and thus played a beneficial role in toughness by 20% at 10% cement replaced. Concrete with a tiny proportion of biochar exhibited the weakest freeze–thaw resistance than control and 10% replacement. Biochar replacement promoted the formation of calcium carbonate. Biochar replacement for partial cement in concrete provides a sustainable option for municipal solid waste management and building energy consumption reduction.

Experimental Study on Preparation and Performance of Concrete With Large Content of Fly Ash

Producing concrete with large content of fly ash attracts increasing attention in low carbon building materials. In this paper, the fly-ash concrete (FAC) with a content of fly ash no less than 50% total weight of binders was developed. The adaptability of fly ash used for concrete was firstly examined by testing the water requirement of normal consistency and the setting time for cement fly-ash paste, and the strengths of cement fly-ash mortar at the curing age of 7 and 28 days. The factors of water-to-binder ratio from 0.3 to 0.5, the content of fly-ash from 40% to 80%, and the excitation measures with additional Ca(OH)2 and steam curing at initial were considered. After that, the FAC was designed by adding an excessive content of fly ash to reduce the water-to-binder ratio from 0.50 to 0.26, and the content of fly-ash varied from 52% to 60%. Results show that the cement fly-ash paste presented a reduction of water requirement and an elongation of setting time with the increased content of fly ash. This provides a foundation of maintaining the workability of fresh FAC with a decreased water-to-binder ratio by adding the excessive content of fly ash. The cement fly-ash mortar had a lower early strength due to the slow reaction of fly-ash with Ca(OH)2, which could be improved by steam curing at the initial 24 h due to the excitation of fly-ash activity. At curing age of 28 days, the FAC had the expected axial compressive strength and modulus of elasticity, but the tensile strength was lower than predicted. At the curing age of 56 days, all the basic mechanical properties of FAC reached the prediction. The resistances of FAC to chloride ion penetration and carbonization were realized at a very high level as specified in codes.

Influence of Potassium-Based Alkaline Electrolyzed Water on Hydration Process and the Properties of Cement-Based Materials with Fly Ash

Alkaline electrolyzed water, a kind of clean green water with excellent characteristics such as high activity, strong alkalinity, high ion penetrating ability, electrical charge, and good molecule adsorption, was significant to the resource utilization of industrial fly ash waste. This paper studies highly active potassium-based alkaline electrolyzed water’s impact, compared with ordinary water, on the cement hydration process using microstructural methods such as a hydration heat test, differential thermal analysis, X-ray diffraction (XRD) pattern, and Scanning electron microscope (SEM) image analysis. Fly ash cement-based materials were first prepared with alkaline electrolyzed water as the mixing water. The alkaline electrolyzed water’s influence on fly ash paste workability and the mechanical properties of fly ash mortar for varying fly ash proportions were ratified. Then alkaline electrolyzed water with the best pH value was selected to prepare fly ash concrete, and its durability was studied. The test results showed that it is feasible to increase the utilization rate of fly ash by using alkaline electrolyzed water. Furthermore, it promoted the process of cement hydration, increased the rate of the hydration reaction, and the promotion effect increased with the increase in pH value of the alkaline electrolyzed water, and also promoted the effective decomposition of the vitreous shell of fly ash to stimulate its early activity. Concurrent tests with ordinary water paste showed that the water requirement for normal consistency and setting time with alkaline electrolyzed water paste were significantly less. Alkaline electrolyzed water also solved the problem related to the low early strength of fly ash mortar. Furthermore, using alkaline electrolyzed water with an optimum pH value of 11.5 to prepare fly ash concrete effectively reduced concrete’s carbonation depth and carbonation rate and lessened the chloride ion migration coefficient.

Recycling of phosphogypsum to prepare gypsum plaster: Effect of calcination temperature

The calcination of phosphogypsum (PG) was employed to produce gypsum plaster to achieve its recovery and utilization. Although previous studies have indicated the possibility of producing hemihydrate and anhydrous gypsum, the influence mechanism of the impurities in calcined PG (CPG) on the properties of plaster is unclear. Herein, the paper aims to investigate the effect of the impurities on the properties of gypsum plaster at elevating calcination temperatures. The phase transformation of PG and impurities were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), and the hydration properties of gypsum plaster were investigated, including water requirement for normal consistency (WR), setting time, compressive and flexural strength, hydration products and degree, and microstructure. The results show that the increase in calcination temperature resulted in higher anhydrite content, and CPG showed similar chemical and mineral compositions at high temperatures (500°C–800 °C). Additionally, harmful impurities barely changed at low calcination temperatures (150°C–400 °C), resulting in the reduced mechanical properties despite its higher hydration degree; however, the calcination at high temperatures converted harmful impurities into inert insoluble calcium pyrophosphate (Ca2P2O7), calcium metaphosphate (Ca(PO3)2), calcium fluoride (CaF2) and sodium sulfate (Na2SO4). With the best calcination temperature of 800 °C, gypsum plaster showed a relatively quick setting and maximum strength with a compact microstructure and low hydration degree due to the large formation of Na2SO4 and nucleation sites. Recycling PG to prepare anhydrite is recommended because of its excellent performance and lower energy consumption than traditional building materials.

A facile approach for large-scale recovery of phosphogypsum: An insight from its performance

The calcination treatment for recycling phosphogypsum (PG) is very promising, which can transform PG into a binder material and remove harmful impurities. To effectively recycle and reutilize PG, the influence of calcination temperatures on the properties of calcined and hydrated PG with and without pretreatment should be investigated. This paper systematically studied the effect of calcination temperature on the properties of water-washed and untreated plaster. The calcined untreated (UPG) and water-washed PG (WPG) were characterized by an X-ray fluorescence spectrometer (XRF), X-ray diffraction analyzer (XRD), and isothermal calorimetry, as well as by determining water requirement for normal consistency, setting time, whereas hydrated PG products were characterized by XRD, differential scanning calorimetry (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG), and scanning electron microscope (SEM), as well as by measuring the mechanical properties. The results show that the chemical and mineralogical composition of calcined untreated PG (CUG) is similar to that of calcined water-washed PG (CWG) at the same calcination temperatures, and higher temperatures resulted in lower F content but no change in P2O5 content. At low calcination temperatures (150 °C–400 °C), the cumulative heat of CUG was lower than that of CWG, and the hydration rate is similar; however, the cumulative heat and hydration rate of CUG at 700 °C or 800 °C were much higher than that of CWG, resulting in the significant reduction in setting time. Hydrated CUG (HUG) showed tiny crystals with lower interlocking at low calcination temperatures, but a more compact microstructure with defined crystals was observed in the HUG-800 due to the high formation of dihydrate gypsum; thus, HUG calcined at low temperature showed a lower strength but at 800 °C showed the maximum strength. This work indicates that calcination at 800 °C showed a potential application for the recovery and utilization of raw PG because of its excellent performance.

The Effect of the Addition of Graphene Nanoplatelets on the Selected Properties of Cementitious Composites

The aim of the current study is to investigate the properties of graphene nanoplatelets-cementitious composites in a consistent sense. The influence of the addition of 2D graphene nanoplatelets (GNPs) on the workability, setting time, flowability, strengths and piezoresistive properties were studied. The dosage of the GNPs is 0 0.05, 0.1, 0.3, 0.5, 0.7, and 1.0 wt% of the binder material. PVP type surfactant was used to disperse GNPs. The experimental results showed that the addition of GNPs increases the water requirement for normal consistency and decreases the flowability. A small amount of GNPs (0.05 wt%) can facilitate the setting. When the dosage of GNPs is above 0.1 wt%, it leads to the delay of the setting time. In terms of the strengths, the addition of GNPs can considerably promote the flexural strength, while the compressive strength is slightly decreased until 28 days. A pre-treatment procedure consisting of drying specimens at 105°C for 1 day can be regarded as a proper way to enhance the piezoresistive properties of the GNPs-mortar. Piezoresistive properties under two different cyclical loading schemes were measured using the GNPs-mortar with 1 wt% GNPs. It has been shown that the average resistance change rate increases with the amplitude increasing and a reduction is observed for the sustained cyclical loading condition. In the end, the influence of the microcracks on the piezoresistive properties was investigated. This study will contribute to future developments of cementitious composites incorporating GNPs for a variety of applications.

Effect of combined activator of Ca(OH)2 and Na2CO3 on workability and compressive strength of alkali-activated ferronickel slag system

The utilization of ferronickel slag into the alkali-activated system is promising to mitigate environmental pollution. Due to slower reaction rate and satisfactory strength, a combined activator of Ca(OH)2 and Na2CO3 (molar ratio of 1: 1) was used to investigate the effect of combined activator content (i.e. 3, 5, 7 and 9% Na2O equivalent) on the workability, water requirement of normal consistency, setting time, soundness and compressive strength of alkali-activated ferronickel slag (AFS) system. X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and mercury intrusion porosimetry were used to characterize the reaction products and pore structure. Results indicate that the workability of AFS system decreases with the increase of Na2O equivalent, while the compressive strength first increases and then decreases. The reaction process is accelerated with Na2O equivalent from 3% to 7%, thereby promoting the formation of C-(A)-S-H gel, calcite and hydrotalcite that can improve the compressive strength. Whereas an increasing porosity due to microcracks is observed at 9% Na2O equivalent, thus resulting in the decrease of compressive strength. Considering the workability and compressive strength, the optimal Na2O equivalent in AFS system is 5%.

Investigation on physical properties, strength and phase evolution of binary cementitious materials made of CFBC ash and lime

Circulating fluidized bed combustion ash (CFBC ash) is the wasteof coal-firedcirculating fluidized bed power plant boiler.CFBC ash contains amounts of free limeand anhydrite, which has a self-hardening andexpansion property. This paper studies the influence of CFBC ash fineness and lime or slaked lime dosage on the physical properties, strength and phase evolution of binary cementitious materials (lime or slaked lime-CFBC ash). The experimental results show that when lime or slaked lime dosage is below 30%, throughCFBC ash getting finer, setting timeof binary cementitious materials becomes shorter and compressive strength of that increases, butwater requirement of normal consistency of that decreases to some extent. And when CFBC ash fineness is constant, with the increment of lime dosage, setting timeof binary cementitious materials becomes shorter and water requirement of normal consistency of that increases, butcompressive strength of that declines first and then increases. But when CFBC ash fineness is constant, with the increment of slaked lime dosage, setting timeof binary cementitious materials becomes longer and compressive strength of that declines, butwater requirement of normal consistency of that increases.

Mechanism of calcination modification of phosphogypsum and its effect on the hydration properties of phosphogypsum-based supersulfated cement

Supersulfated cement (SSC) is a kind of environment-friendly and energy-saving cement, which is almost entirely made of industrial waste and could consume a lot of phosphogypsum (PG), which has great potential for industrial application. The calcination treatment at the temperature of 150 °C, 350 °C, 600 °C, 800 °C with calcination time of 0.5 h, 1 h, 1.5 h, 2 h is used to improve the performance of PG. The phase transformation of PG, the removal of soluble phosphorus impurities, and the hydration properties of SSC containing PG with or without modification are investigated, including the water requirement of normal consistency and setting time, the compressive strength, the pH value of pore solution and the microstructure performance of pastes. The relationship between these properties and calcination pretreatment processes are established as well. The results show that the calcination pretreatment of PG reduced the adverse effects of impurities in PG and changed the gypsum phase to prepare SSCs with higher performance in all aspects. While the modification effect varied with calcination temperature and calcination time, 90% of the setting time was shortened after calcination temperature of 350 °C for 2 h, which makes the PG-incorporated SSC meet the requirements of existing standard. And high temperature treatment showed the best modification effect on strength, especially after calcination at 600 °C for 2 h, both early and later strength was significantly increased, which was almost twice of the reference specimen. Besides, more formed hydration products and the denser microstructure were observed in the specimen with high temperature treated PG. Moreover, the slight decreases of 90-day compressive strength in some specimens were observed, which could be due to the carbonation of the specimen.

Effect of Residual CaSO4 in Clinker on Properties of High Belite Sulfoaluminate Cement Based on Solid Wastes.

The high belite sulfoaluminate cement (HBSAC) containing CaSO4, and without CaSO4, based on solid wastes were successfully prepared from petroleum coke desulfurization slag (PCDS), fly ash (FA), carbide slag (CS), and bauxite (BX). The mineral composition of clinkers after different calcination history were investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD)/Quantitative X-ray diffraction (QXRD), and scanning electron microscopy (SEM), so as to determine the calcination temperatures. The difference between residual CaSO4 and dihydrate gypsum (DG) and the optimal content of residual CaSO4 were discussed by studying the properties of HBSAC. The results revealed that the residual CaSO4 in clinker could replace DG to participate in hydration, and showed some advantages in strength and early hydration heat, but meanwhile increased the water requirement of normal consistency and hydration heat at 72 h, and prolonged the setting time. With the increase of residual CaSO4 content in clinker, the lower limit temperature of clinker formation gradually increased, and the crystal size of clinker minerals became finer and the boundary between crystals became more blurred. However, the optimal calcination temperature (1300 °C) of HBSAC clinker did not change. Considering the effect of residual CaSO4 content on the water requirement of normal consistency, setting time, hydration heat, strength, and hydration products, the optimal design content of residual CaSO4 in HBSAC clinker based on solid wastes, such as PCDS and FA, was 15%.

Research on the Preparation and Properties of High Belite Sulphoaluminate Cement (HBSAC) Based on Various Industrial Solid Wastes.

In this study, a variety of industrial solid wastes, including petroleum coke desulfurization slag, fly ash and carbide slag with natural resource bauxite, were used as raw materials to prepare high belite suphoaluminate cement, which contains a certain CaSO4 content without adding natural gypsum to the clinker. The sintering temperature, mineral composition, and the physical and mechanical properties of the cement clinkers were investigated. The techniques adopted included a comprehensive thermal analysis (DSC-TG), X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The results revealed that it is completely feasible to prepare high belite sulphoaluminate cement with the various industrial solid wastes mentioned above and the utilization rate of the solid wastes is up to 80%. The sintering temperature ranges from 1225 °C to 1350 °C, and the optimal sintering temperature is approximately 1300 °C. The clinkers prepared at 1300 °C set and harden quickly and have a slightly higher water requirement of normal consistency. The mechanical strength is greatly affected by the CaSO4 and 3CaO·3Al2O3·CaSO4 contents and the most reasonable CaSO4 content is 15%.

L-aspartic acid: A crystal modifier for preparation of hemihydrate from phosphogypsum in CaCl2 solution

L-aspartic acid (L-Asp) was proposed as crystal modifier to regulate the morphology of hemihydrate (HH) prepared from phosphogypsum (PG) in CaCl2 solution. Effect of L-Asp on dehydration kinetics of PG, morphology and mechanical properties of HH as well as microstructure of hardened gypsum were investigated by crystal water content, strength and SEM measurements. The adsorption mechanism of L-Asp onto the HH crystals was explored by FTIR, XPS and zeta potential analyses. The results show that the L-Asp chemisorbs on the surfaces of HH by carboxyl (COO−) complexing with Ca atoms, and reduces the dehydration rate of PG to HH by extending the crystal growth period. The dehydration kinetics can be well described by the Boltzmann equation. With increasing L-Asp concentration from 0.00 to 2.50 mM, the HH crystals are shortened in length and enlarged in width with the aspect ratio decreasing from 5.74 to 1.21; meanwhile, the water requirement of normal consistency decreases from (41.5 ± 0.7)% to (31.2 ± 0.3)% and the corresponding bending/compressive strengths increase from (6.2 ± 0.6)/(13.1 ± 1.1) MPa to (10.7 ± 0.7)/(30.2 ± 1.4) MPa, respectively. Furthermore, the hardened gypsum presents a more compact microstructure with uniform in size and morphology in the presence of 2.50 mM L-Asp in comparison with blank test. Therefore, it can be concluded that the L-Asp is an effective crystal modifier for preparation of short columnar HH.

The early hydration of metakaolin blended cements by non-contact impedance measurement

This paper aims to study the early-age hydration process of metakaolin blended cement pastes. The hydration characteristics of different stages, i.e. first dissolution, acceleration, second dissolution and hardened stage, are analyzed by non-contact impedance measurement (NCIM), X-ray diffraction (XRD), derivative thermogravimetric analysis test (DTG), and Fourier transform infrared spectroscopy (FTIR). Through the comprehensive investigation, the second dissolution stages corresponding to the plateau segments appearing in impedance modulus curves for metakaolin blended cement pastes, seem to be associated with the dissolution behavior of metakaolin in alkaline condition. The larger amount of metakaolin in the paste results in the more distinct plateau or descent segment. Furthermore, 15% metakaolin replacement is most favorable to enhance the hydration rate and broaden the range of pore size distribution of blended cement paste. Meanwhile, the compressive strength, water requirement of normal consistency and setting time of blended pastes are examined to study their macro-physical performances.

Utilization of waste glycerin, industry lignin and cane molasses as grinding aids in blended cement

This paper investigates the viability of using waste glycerin (WG), industry lignin (IL) and cane molasses (CM) used as grinding aids in blended cement, performance of the blended cement with single and composite grinding aids were researched. The structure characterization of the grinding aids was carried out by Fourier transform infrared spectroscopy (FT-IR); the particle size distribution, Blaine specific surface area, setting times, water requirement of normal consistency, flexural and compressive strengths at 3 and 28days of the blended cement were researched, the experiments results indicate that the addition of grinding aids results in an improvement of the fineness and strength of the blended cement. Compared with the cement mixture without grinding aids, waste glycerin has a better optimization effect on the particle size distribution, industry lignin and cane molasses perform a better retarding effect, and enhancement effect of cane molasses on the strength of blended cement is more significant. For the blended cement with composite grinding aids (0.0065% WG, 0.0095% IL, 0.024% CM), the compressive strength at 3days and 28days are 2.6MPa and 10MPa higher than those of the control cement respectively. The hydration products and microstructure of blended cement with composite grinding aids were analyzed by X-ray diffraction (XRD), thermo-gravimetric and differential scanning calorimetry (TG-DSC) analysis and scanning electron microscopy (SEM), the research shows that for the blended cement, the addition of grinding aids can accelerate the hydration reaction degree and improve the compactness and uniformity of the products structure.

Effect of ground steel slag powder on cement properties

The work aims to evaluate the influences of steel slag's fineness and particle-size distribution on the properties of cement-based materials. The materials used for this study included Portland cement and steel slag powder with seven different specific surface areas. The properties of cement pastes and mortars with steel slag powder were tested including water requirement of normal consistency, setting time, fluidity, soundness, compressive and flexural strength. The experimental results show that the influence of steel slag powder on water requirement of normal consistency of cement is in relation to its specific surface area, and the value of decreases for steel slag powder with a lower-specific surface area while increases with a higher-specific surface area. The partial replacement of cement by steel slag powder decreases the strength of cement, but increases the ratio of flexural to compressive strength and thus improves the ductility of cement-based materials.