Content Of Mineral Admixtures Research Articles

Optimization of mix proportion and strength prediction of magnesium phosphate cement-based composites based on machine learning

In order to optimize the mix ratio design of magnesium phosphate cementitious composites (MPCC) to obtain excellent workability and strength, this study investigated the effects of MgO-phosphate ratio, water-binder ratio, aggregate-binder ratio, the mass ratio of coarse and fine aggregates, mineral admixture content and steel fiber content on the flowability, setting time and cubic compressive strength (CCS) of MPCC using orthogonal design of experiments with a total of 32 sets of mix ratios. The experimental results were also analyzed utilizing range and variance analysis to determine the main influencing parameters and the optimal dosage of each factor, and the optimal MPCC mix ratio was obtained. In addition, the prediction of CCS for MPCC using five machine learning models was first introduced, and the predicted results were interpreted and analyzed regarding the SHAP (Shapley Additive exPlanations) features importance. The results showed that the effect of steel fiber volume content and water-binder ratio on the flowability was significant, and M/P significantly affected the setting time of MPCC. The CCS of MPCC increased with the age of curing, and MPCC exhibited high early strength, with 1-day CCS accounting for 55%～85% of the 28-day CCS. The effect of M/P on the 1-day, 3-day and 28-day CCS was highly significant, with M/P contribution rate as high as 76.3%, 80.3% and 83.6% of the CCS at 1, 3 and 28 days, respectively. Besides, the effect of steel fiber volume content on 28-day CCS was also significant. In summary, the optimal mix ratio of MPCC was A4B1C4D1E4F4G1 (M/P = 3, w/b=0.11, a/b=1.4, c/f=3, FA content =15%, MK content= 15%, steel fiber volume content= 0%). Furthermore, random forest (RF) and particle swarm optimization of back propagation artificial neural network (PSO-BP-ANN) models have a higher prediction accuracy, and the results of SHAP feature significance further confirmed the above test results.

Experimental study and simulation of workability and compressive performance of SCC with high-volume mineral admixtures

Using industrial waste such as fly ash and silica fume to substitute most of the cement to prepare self-compacting concrete can not only greatly reduce the cement consumption, but also improve the resource utilization of solid waste powder, which is conducive to cost reduction and environmental protection. In this paper, the fly ash (FA) and silica fume (SF) replacement ratio of 40%, 50% and 60% was adopted to produce self-compacting concrete with high-volume mineral admixtures (HVMA-SCC). The slump flow test, L-box test and compression test were conducted, and the effect of different high replacement ratio on the workability, compressive performance and stress–strain relationship of HVMA-SCC were analyzed. The experimental results showed that when the total content of mineral admixtures was the same, an increase in SF content was beneficial for the development of early compressive strength. Under the same SF dosage, the larger the FA dosage, the faster the strength development rate, which was conducive to the sustained growth of HVMA-SCC strength in the later stage. Moreover, a stress–strain calculation model of HVMA-SCC was proposed based on damage theory. Besides, the workability and compression tests were simulated with the discrete element method (DEM). The results showed that the simulated stress–strain curves were in good agreement with experimental curves, and the mesoscopic failure characteristics of HVMA-SCC were analyzed from the development of cracks, stress conditions, and failure modes.

Low-Field Nuclear Magnetic Resonance Investigation on Early Hydration Characterization of Cement Paste Mixed with Mineral Admixtures

Mineral admixtures (MA), like fly ash (FA), silica fume (SF), and slag (S), are usually added to cement-based materials to improve their compactness and further enhance their mechanical properties, permeability resistance, and durability. In this study, low-field nuclear magnetic resonance (LF-NMR) is adopted to explore the evolution of the early hydration characterization of cement-based materials with MA by testing the transverse relaxation time T2. Meanwhile, the effect of MA on mechanical properties is analyzed by measuring compressive and flexural strength. The results show that, in the early hydration (0–7 days), the T2 distribution shows a trend of gradually moving to a short relaxation time and changes from a double peak to a single main peak. The decrease in T2i (main peak vertex) means that the evaporated water is gradually distributed in smaller pores with more motion constraints. However, the type and content of MA have little effect on T2i. Porosity gradually decreases in the period of early hydration. The addition of MA causes the porosity to decrease, and the order influence is FA > S > SF, i.e., the porosities of cement paste with 0%MA, 10%FA + 10%SF, 10%FA + 10%S, and 20%FA at 7 days are 48%, 44.5%, 40.7%, and 40.2%, respectively. Additionally, the addition of MA to cement-based materials also decreases the early strength, and the influence order is FA > S > SF, i.e., the compression strength values of cement paste with 0%MA, 10%FA + 10%SF, 10%FA + 10%S, and 20%FA at 7 days are 47.8 MPa, 40.1 MPa, 38.6 MPa, and 37 MPa, respectively.

Preparation and Mechanical Properties of Low Carbon Cementitious Materials with Superfine Cement Reverse Filling High-Volume Mineral Admixtures.

In order to increase the content of mineral admixtures in cement, this study proposes a method for preparing a high-volume mineral admixture cementitious material (HMAC) using superfine cement as a reverse filling material. Firstly, superfine cement is prepared through mechanical grinding. Then, the activity of mineral admixtures (such as slag and fly ash) is enhanced by mechanical grinding, sulfate activation, and alkali activation methods. Meanwhile, the evolution of HMCM from microstructure to macroscopic mechanical behavior is studied by combining a laser particle size analyzer and a scanning electron microscope. Furthermore, the reverse filling mechanism of superfine cement on mineral admixtures under different activation conditions is proposed. Results show that superfine cement can largely improve the utilization rate of cement clinker and the compressive strength of cementitious materials. In the condition that the compressive strength is not lower than that of the control group (without mineral admixture), the content of mineral admixture can be increased to 50%, 70%, and 90% after mechanical grinding, sulfate activation, and alkali activation, respectively. Analysis indicates that the reverse filling effect of superfine cement is the main reason for improving the density of the HMCM.

Mechanical characteristics of fiber-reinforced microcapsule self-healing cementitious composites by orthogonal tests

This study combined the microcapsule self-healing system with fiber reinforced concrete (FRC), and investigated the effects of microcapsule content, mineral admixture type, mineral admixture content, and fiber type on tensile and compressive strength, ductility, and self-healing properties of the fiber-reinforced microcapsule self-healing cementitious composites by the orthogonal test method. For the uniaxial tensile and cubic compression tests, the optimum tensile strength group consists of a 2.2 mass ratio of GGBS, PE fiber, and no microcapsules. The optimum compressive strength group consists of a 2.2 mass ratio of GGBS, hybrid fiber, and no microcapsules. Microcapsule content and fiber type are the main factors affecting tensile properties, and an increase in the microcapsule content will reduce the tensile strength and compressive strength of the matrix. The optimum tensile strain group consists of 10% microcapsule content and a 2.2 mass ratio of GGBS and PE fiber. The results of the energy-based steady-state crack propagation test show that the fiber type is the most critical factor affecting the ductility, and the tensile ductility of the PE fiber group is higher than that of the PVA fiber group. The scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) diagram proved the healing effect of the fiber-reinforced microcapsule self-healing cementitious composite.

Influence of Mineral Admixtures on the Properties of Magnesium Oxychloride Cement Lean Concrete

This study investigated the effects of light-burned magnesia, fly ash (FA), dolomite powder (DP), and limestone powder (LP) contents on the performance of magnesium oxychloride cement lean concrete (MOCLC). The effects of light-burned magnesia and mineral admixture content on the mechanical properties and durability of MOCLC were tested by the compressive strength test, splitting strength test, water resistance test, shrinkage test, and fatigue test, respectively. The results revealed that the optimum dosage of MgO was 4%. The optimum dosages of FA, DP, and LP were 25%, 20%, and 20% of the cement dosage, respectively. The compressive and splitting strengths of the MOCLC were decreased by the addition of FA and DP. Due to part of the internal pores of MOCLC were filled with FA and DP, the decomposition of the main strength phase 5Mg (OH)2·MgCl2·8H2O (phase 5) was suppressed and the water resistance of MOCLC was improved. The addition of FA and DP also improved the shrinkage resistance, and the fatigue resistance of MOCLC was also improved by the addition of FA and DP. The water resistance, shrinkage, and fatigue properties of MOCLC with a FA content of 25% were better than those of MOCLC with DP and LP.

Preparation of water-quenched manganese slag and fly ash ultrafine mineral admixture and its application in UHPC

Abstract In this paper, S95 grade ultrafine mineral admixture (UMA) was prepared by water quenched manganese slag and fly ash 1:1 compound mechanical ball milling to a specific surface area of 714 m2/kg. Its activity index was 86.8% at 7d and 96.3% at 28d. The S95 UMA prepared by ball milling has the characteristics of small particle size, high specific surface and high activity. Mixing with powders of different particle sizes, such as cement and silica fume (SF), is helpful to improve particle gradation, reduce its pore structure and increase its compacting property for ultra-high performance concrete (UHPC) whose raw materials are fine aggregate. UHPC was prepared by using the obtained UMA based on orthogonal test. The effects of different factors on the workability, mechanical properties, hydration heat and microstructure of UHPC were studied. The results show that when the SF content is 10%, the mineral admixture content is 10%, the binder–sand ratio is 1.1, and the water–binder ratio is 0.17, the fluidity of UHPC slurry can reach 261 mm, the compressive strength of 7d and 28d age can reach 128 MPa and 154.6 MPa, respectively. The hydration heat release of cementitious materials in 3d was 139.8 J/g. In terms of solid waste resource utilization, S95 grade UMA prepared by water-quench manganese slag and fly ash can replace 10% SF for the preparation of UHPC. It can not only solve the utilization problem of high added value of water quench manganese slag but also reduce the preparation cost of UHPC to a certain extent.

Research on mechanical and electromagnetic shielding properties of cement paste with different contents of fly ash and slag

This paper studied the mechanical properties and electromagnetic shielding effectiveness of cement paste (CP) mixed with fly ash and slag. With pure CP as the control group, 10%, 20%, and 30% cement contents were replaced by fly ash and slag. Then the compressive and flexural strength of the samples were tested. Wet resistance and dry resistance of samples were tested by the four-probe technique. The electromagnetic shielding effectiveness of the sample in the 3.94 GHz–5.99 GHz band was tested. Finally, based on the mercury intrusion porosimetry (MIP) test and backscattered electron and energy-dispersive X-ray spectroscopy (BSE-EDS) test, the impact mechanism of fly ash and slag on the electromagnetic properties of CP was expounded from the pore structure and element distribution. The results show that with the increase of fly ash or slag, the strength of the sample decreased. Mineral admixtures had little effect on wet resistance, while dry resistance showed an increasing trend with the increase of mineral admixture content. The reflection loss had the greatest impact on electromagnetic shielding effectiveness. With the increase of mineral admixture content, the reflection loss and multiple reflection loss of the sample increased, but the absorption loss decreased. The reason for the effect of compounding different proportions of fly ash and slag on the electromagnetic shielding effectiveness of CP is mainly due to the change in the proportion of mesopores with an aperture less than 100 nm and the content of metallic elements (e. g. Fe) in the specimens.

Experimental study on effect of fly ash content on self-compacting concrete

Self-compacting concrete (SCC), concrete flows by its own weight, is a recent innovation in concrete industry. In recent times, the usage of self-compacting concrete was increasing. Self-compacting concrete will be form, if it had sufficient binder content and required water content. The strength of concrete majorly depending on water to powder ratio. However, there were workability problems associated while fixing the water powder ratio as per target mean strength when SCC was made, especially for design mix for low strength and high strength of concrete. Apart from this, binder content and mineral admixture will also responsible for strength of concrete. As mineral admixture content increases the strength will reduce. If a relationship between compressive strength and mineral admixture content was found, mix proportions of SCC can be made easily. In this area more research has to be focused. This research is an attempt to assessing the grade of concrete with respect to fly ash content and relationship was developed between fly ash content and compressive strength of concrete. IS 10262-2019 and EFNARC guidelines are used in mix design. A water content of 200 kg/m3 and water powder ratio = 0.4 is kept as constant. Cement was partially replaced with fly ash at proportions of 10%, 20%, 30%, 40%, and 50%. In this research the fresh properties, mechanical properties, and Sulphate attack test of each proportion were tested. The workability properties are measured under different chemical admixture levels, such as 0.5%, 0.6%, and 0.8%. Strength properties are determined with a chemical admixture dosage of 0.6%. The fresh properties of concrete were measured by slump flow test, L–box test, and V–cone test. Mechanical properties such as compressive strength, flexure strength and split tensile strength were determined. Sulphate attack test also conducted by immersing cube specimens in 5% of H2SO4. Further, correlation study was done between compressive strength & fly ash content and also correlation between compressive strength & flexure strength.

Influence of mineral admixtures on high performance concrete

Taking high performance concrete (HPC) in hydraulic engineering as an example, this paper discusses the influence of different mixing methods of slag powder and fly ash on its frost resistance and chloride ion permeability. The results show that the compressive strength decreases with the addition of HPC; Proper addition of mineral admixtures is beneficial to improve the anti chloride ion permeability of HPC and reduce the electric flux; The HPC flux of 28d and 90 reaches 680C and 280C, when the mass ratio of slag powder to fly ash is 15:35 and the content of mineral admixture is 35 %; The frost resistance of HPC gradually deteriorates with the increase of mineral admixture under the condition of constant air content and water binder ratio. The frost resistance grade of HPC without mineral admixture reaches F200, and its frost resistance is the best.

Environmental and Mechanical Evaluation of Blended Cements With High Mineral Admixture Content

The synergistic effect of combining supplementary cementitious materials (SCMs) as partial substitutes for clinker improves cement properties and reduces its clinker factor and, hence, its carbon footprint. Limestone-calcined clay cement (LC3)—a family of clinker, calcined clay, and limestone filler mixes—is studied worldwide for its properties equivalent to those of Portland cement. Although slag and fly ash are no longer sufficient to keep up with current commercial blended cements, in the long run, these SCMs can support the development of optimized formulations for the future. By relating the environmental and the mechanical performances, the GHG emission intensity offers a broader assessment and selection perspective. In this article, 13 blended cements were evaluated: ternary, quaternary, and multi-admixture (i.e., OPC plus 4 SCMs) blends with clinker factor between 40 and 50%, composed of—in addition to calcined clay and limestone filler—blast furnace slag and fly ash. Compressive strength was measured at 3, 7, 28, 91, and 365 days. The greenhouse gas (GHG) emissions were estimated through life cycle assessment and related to the blends’ compressive strength unit. Quaternary and multi-addition cements consistently outperformed after 3 days of age, demonstrating the benefits of the synergistic effect between SCMs jointly on GHG emissions and compressive strength. Such an effect enables reducing not only the clinker factor and carbon footprint but also the GHG emission intensity, which relates both. This study showed that the formulated cements, particularly those composed of multi-additions (Series D), are potential alternatives for reducing the GHG emissions, whilst preserving mechanical performance demanded by construction market practices. From a multidisciplinary analysis standpoint, durability assessments are necessary to complement the reported findings, as low clinker contents can affect the pH of the concrete’s pore solution and carbonation which ultimately lead to deterioration.

Degradation Law and Service Life Prediction Model of Tunnel Lining Concrete Suffered Combined Effects of Sulfate Attack and Drying-Wetting Cycles.

The present study explored the degradation law and service life prediction of tunnel lining concrete with different mineral admixtures under coupled actions of sulfate attack (SA) and drying–wetting (DW) cycles. The deterioration resistance coefficient (DRC) of compressive strength and influence coefficients of sulfate concentration, mineral admixture content, water/binder (w/b) ratio, and curing regime on DRC were studied. After that, a new service life prediction model based on damage mechanics was developed and analyzed. Results show that, by increasing the DW cycles, the DRC first increases and then decreases. DRCs of Ordinary Portland cement (OPC), fly ash (FA), and ground granulated blast-furnace slag (GGBS) concrete linearly decrease with the increase of sulfate concentration, while the silica fume (SF) concrete displays a two-stage process; by increasing the admixture content, the DRCs of FA and GGBS concrete exhibit two distinct stages, while the SF concrete depicts a three-stage process; increasing the w/b ratio linearly decreases the DRC; the DRC of curing regime was sequenced as standard curing (SC) > fog curing (FC) > water curing (WC) > same condition curing (SCC). Based on the experimental results, the service life prediction model is applied and validated. The validation results show that the proposed model can accurately predict the lifetime of concrete with different mix proportions. Furthermore, it is found that the mineral admixture can effectively improve the lifetime of concrete, and the composite mineral admixture is more effective than a single mineral admixture in improving the lifetime of concrete.

Study on the Mechanical Properties, Wear Resistance and Microstructure of Hybrid Fiber-Reinforced Mortar Containing High Volume of Industrial Solid Waste Mineral Admixture.

The use of a high volume of industrial solid waste mineral admixture and hybrid fiber can greatly reduce the amount of cement in mortar or concrete, improve its performance, ensure the service properties of mortar or concrete, and reuse industrial solid waste to reduce the environmental burden, which has significant research significance. In this paper, the mechanical properties, wear resistance and microstructure of hybrid fiber-reinforced mortar (HFRM) with a high content of industrial solid waste mineral admixture were systematically studied under different water/binder ratios. Mineral admixtures include fly ash, silica fume and granulated blast furnace slag (slag). The total content of hybrid glass fiber (GF) and polypropylene fiber (PPF) was 2% by volume fractions, and six different water/binder ratios ranging from 0.27 to 0.62 were used. The following conclusions were drawn: fibers have a significant negative effect on the properties of mortars with a low water/binder ratio (w/b = 0.27) and high content of mineral admixtures. In general, the effect of adding hybrid fiber on improving the wear resistance of mortar is more obvious. The average residual weight of hybrid fiber-reinforced mortar is the highest after the wear resistance test. Comprehensively considering the compressive strength, flexural strength, wear resistance and microstructure of the mortar samples, G8PP2-0.40 is the optimal mix ratio. At this time, the replacement rates of fly ash, silica fume and slag are: 20%, 5% and 30%, the water/binder ratio is 0.40, and the content of GF and PPF is 1.6% and 0.4%, respectively.

Research on Curing Water Demand of Cementing Material System Based on Hydration Characteristics.

The performance of cover concrete is acknowledged as a major factor governing the degradation of concrete structures. Curing plays a vital role in the development of concrete durability. The effects of different water-binder ratios and mineral admixtures on the curing water demand of concrete were studied by the surface water absorption test. Combined with the characteristics of the hydration heat and chemically bound water of the composition cementing material system, the law of variation for curing water demand was analyzed. The results show that the addition of mineral admixtures can reduce the early hydration rate and hydration exothermic characteristics, and the hydration degree decreases with the increase of mineral admixtures. Due to the filling effect and active effect, the addition of fly ash (FA) and ground granulated blast slag (GGBS) reduces the curing water demand. The curing water demand of cover concrete decreases with the increase of mineral admixture content, and the curing water demand of pure water is the maximum and that of mix FA and GGBS is the minimum. Moreover, there is a strong correlation between the cumulative curing water demand and the chemically bound water content, indicating that the power of water migration mainly comes from the hydration activity of the cementing material system. The results provide a theoretical basis for the fine control of a concrete curing system.

Eco-friendly UHPC prepared from high volume wet-grinded ultrafine GGBS slurry

The development of ultra-high performance (UHPC) concrete was restricted due to the large consumption and high cost of cement. In this study, eco-friendly UHPC was prepared by ultra-high content of wet-grinded ultrafine ground granulated blast furnace slag (UGGBS). And the content of mineral admixture in the cementitious system is up to 50%, of which UGGBS is as high as 40%. It was proved that the mechanical development, microstructure and hydration process of UHPC were significantly improved by UGGBS. The results showed that the compressive strength of G0UG20 was increased by 27% and 15% at 3 and 28 days compared with the reference group. Even if the cement content was reduced, the compressive strength of high volume UGGBS blended UHPC was still higher than the reference group. The addition of UGGBS significantly refined the pore structure and densified the hardened system. Meanwhile, the MCL and Al/Si of C-S-H gels were improved by UGGBS. In terms of environmental and economic benefits, the CO2 emissions and production costs were reduced by the addition of UGGBS.

Material design and engineering application of Fair-faced self-compacting concrete

Fair-faced concrete (FFC) with excellent decorative effect is a kind of concrete which can be directly used as external facade, whereas the low workability and complex molding process of the ordinary FFC restricts its broad application. In this study, the C40 self-compacting FFC (named as fair-faced self-compacting concrete or FFSCC for short) was prepared. With the reference of average paste thickness (APT) theory, the effects of coarse aggregate gradation and content, sand content and mineral admixture content on workability, compressive strength and decoration effect of FFSCC were quantitatively analyzed to obtain an optimal mix proportion of FFSCC. The results indicated that the increased proportions of 5–10 mm aggregates or higher aggregate content would lead to the lower APTs, which resulted in lower workability, lower surface porosity, and higher strength. Fitting results between APT and several properties presented that the fluidity, flow velocity and compressive strength possessed the linear relationships with APT values. While the passing capacity, segregation ratio and surface porosity possessed the quadratic polynomial relationships with APT values. Furthermore, atomic force microscopy (AFM) was applied to observe the surface texture of FFSCC. Results showed that its surface roughness (RMS) was 3.7 nm, which was smoother than the polished cement paste. Finally, the optimal FFSCC was successfully applied in second lining of Nan Kunshan tunnel.

Insights into the effect of NaOH on the hydration products of solidified cement-NaNO3 matrices and leaching behavior of Sr2+

The low-level and intermediate-level radioactive waste is generally an alkaline solution with high concentration of sodium salts. Moreover, extra NaOH will be added into the matrices when the high content of mineral admixtures is used in the preparation of solidified cement matrices. This study mainly researches the influence of NaOH on the structure of C-S-H gels and the leaching rate of Sr2+ in the solidified cement matrices by isothermal conduction calorimetry, X-ray diffractometry, thermogravimetry, 29Si nuclear magnetic resonance, mercury intrusion porosimetry and inductively coupled plasma. The results show that the addition of NaOH accelerated the hydration of cement in the early age but decreased the normalized hydration heat until 28 days. Also, the fraction of total Ca(OH)2 decreased with the increasing content of NaOH. Moreover, NaOH promoted the formation of C-S-H gels along the main chain by increasing the mean chain length but decreased the Q3 sites. However, the addition of NaOH has optimized the pore structure through reducing the porosity and median pore diameter. At last, the cumulative leaching fraction of Sr2+ at the NaOH content of 10% decreased by 17.5% compared to the NaOH content of 0.82%. Based on the results, it can be concluded that NaOH enhanced the adsorption capacity of C-S-H gels to Sr2+ and improved the immobilization performance of solidified cement matrices.

Effect of number of neurons and layers in an artificial neural network for generalized concrete mix design

Selection of the number of neurons in different layers of an artificial neural network (ANN) is a key decision-making step involved in its successful training. Although the number of neurons in the input layer is decided by the number of input parameters, and similarly, in the output layer the number of neurons is fixed by the output parameters, however, the number of neurons in the hidden layer is not fixed, whereby the overall efficiency of the ANN depends upon the correct modeling of the realistic scenario in the form of a neural network. Concrete can be mixed in a huge variety of methods and compositions to achieve a specific or a combination of specific results. These results have been observed to repeat and follow patterns. Furthermore, for several types of concrete mixes, only actual physical trial data are available with no mix design method; this makes achieving different required results very complex and expensive task. Having an ANN to be able to predict a concrete mix to handle such variations will save a lot of time and money and will prove to be a universal mix design tool. A thorough analysis for deciding the number of neurons for mix design of concrete has been carried out in this research. The results of neural networks for a varying number of neurons and layers have been correlated. The data for a number of concrete mixes were sorted and normalized. Properties of concrete constituents like specific gravity of cement, coarse and fine aggregates, dry density of coarse and fine aggregates, cement type, type of mineral admixture, water-to-cement ratio, type and temperature of curing and hardened properties like compressive strength, modulus of elasticity and tensile strength were taken as input parameters. The contents of constituents of concrete such as water content, cement content, coarse aggregates content, fine aggregates content and content of mineral admixtures are regarded as output parameters. For 17 inputs and 5 outputs, it has been discovered that simple neural network with single or double hidden layers performed better that 3 or more such layers.

Experimental Study on the Flexural Strength of Marble Industrial Powder Concrete

The flexural strength and cube compressive strength of marble industrial powder concrete were studied by orthogonal test method. 25 orthogonal test groups and 1 contrast test group with the mineral admixture content 0% were designed to carry out the flexural and compressive tests. The strength of concrete with different substitution rate and fineness is obtained, and the mechanism of influence on each strength is analyzed. The experimental results show that the concrete flexural strength is reduced by the addition of marble powder, but it can meet the requirement of engineering application when the substitution rate is less than 10%. According to the orthogonal test, the main factor affecting the flexural strength of marble industrial powder concrete is the substitution rate of marble powder, and the secondary factor is the fineness of marble powder. The effect of marble powder on the flexural strength and compressive strength of concrete is basically the same. The ratio of flexural strength to cubic compressive strength of marble powder concrete with different substitution rate and fineness is 0.16.

Experimental Study On Properties Of High-Early-Strength Cementitious Grout

This paper studied the influences of mineral admixture content on the fluidity, compressive strength and vertical expansion rate of the cementitious grout, which based on a ternary composite cementitious material system of sulfoalminate cement, protland cement and gypsum. The influences of fly ash, slag powder and silica fume were investigated respectively. It was shown that: (1) The initial fluidity grew as the addition of fly ash content in the cementitious grout, 1 d compressive strength and 3 d compressive strength were reduced. (2) The slag powder had great impact on the fluidity, when the content of slag powder more than 18%, initial and 30 min fluidities declined. With the slag powder increased, 1 d, 3 d and 28 d compressive strengths decreased slightly, while 3 h vertical expansion rate increased. (3) The increased of silica fume content made the compressive strengths rised first and then fell. 1 d, 3 d and 28 d compressive strengths could reach their maximum values, when the amount of silica fume was 3.0%.