Silica Fume Cement Research Articles

Carbonation Resistance of Ternary Portland Cements Made with Silica Fume and Limestone.

Ternary blended cements, made with silica fume and limestone, provide significant benefits such as improved compressive strength, chloride penetration resistance, sulfates attack, etc. Furthermore, they could be considered low-carbon cements, and they contribute to reducing the depletion of natural resources in reference to water usage, fossil fuel consumption, and mining. Limestone (10%, 15%, and 20%) with different fineness and coarse silica fume (3%, 5%, and 7%) was used to produce ternary cements. The average size of coarse silica fume used was 238 μm. For the first time, the carbonation resistance of ternary Portland cements made with silica fume and limestone has been assessed. The carbonation resistance was assessed by natural carbonation testing. The presence of coarse silica fume and limestone in the blended cement led to pore refinement of the cement-based materials by the filling effect and the C-S-H gel formation. Accordingly, the carbonation resistance of these new ternary cements was less poor than expected for blended cements.

Experimental investigation on the seismic behavior of TRAC frame column with RCA treated by the silica fume cement paste

AbstractThe physical properties of recycled coarse aggregate (RCA) can be strengthened by pre‐soaking them in silica fume cement paste, thereby improving the mechanical properties of recycled concrete. To evaluate whether treated recycled coarse aggregate (TRCA), which is obtained by pre‐soaking in silica fume cement paste, can be applied to structural elements, considering the axial compression ratio and volumetric stirrup ratio, TRCA concrete (TRAC) frame column specimens and natural aggregate concrete (NAC) column specimens were prepared. Subsequently, a cyclic loading test was conducted on the specimens. The failure mode, hysteresis loop, skeleton curve, ductility, and energy dissipation capacity of the specimens were analyzed and compared. The results showed that compared with NAC specimens, the bearing capacities of the TRAC specimens were slightly higher. The seismic behavior of the TRAC frame columns achieved performance level similar to that of the NAC structural members at low axial compression ratios. This indicates that the RCA treatment of pre‐soaking in silica fume cement paste is effective, and TRAC can be used as loading‐bearing structural concrete.

Development of Reactive MgO Cement-Silica Fume–Based Strain-Hardening Engineered Cementitious Composite

Development of Reactive MgO Cement-Silica Fume–Based Strain-Hardening Engineered Cementitious Composite

Effect of sulfate on the compatibility between polycarboxylate superplasticizer and cement-based materials with or without silica fume

Polycarboxylate superplasticizer (PCE) is a crucial raw material used for preparing concrete. However, there has always been a compatibility issue between PCE and different types of cementitious materials due to their varying qualities. In concrete raw materials, the types and contents of sulfates have a significant impact on compatibility, and it is well-established that a competitive adsorption exists between PCE and sulfate ions solubilized in the interstitial solution of cement paste, which may cause a loss of the dispersing properties. However, previous studies focused on the effect of sulfate on the compatibility between PCE and cement, and there was a lack of research on silica fume. In this study, the workability of fresh cement and cement-silica fume paste and the mechanical properties of harden mortar were evaluated in the presence of different concentrations of five types of sulfates (Na2SO4, K2SO4, MgSO4, KAl(SO4)2, and CaSO4·2H2O) added in aqueous solution. The results show that soluble sulfates have a more adverse effect on the compatibility between PCE and cement-based materials with or without silica fume than slightly sulfate. And the effects of different sulfates on saturation points of PCE in cementitious materials and the mechanical properties of cement and cement-silica fume mortar are various. Finally, it is important to note that a high sulfate content in the solution can lead to salt precipitation of PCE, which is highly undesirable.

Effect of Silica Fume on Compressive Strength and Water Absorption of the Portland Cement–Silica Fume Blended Mortar

Effect of Silica Fume on Compressive Strength and Water Absorption of the Portland Cement–Silica Fume Blended Mortar

Influence of glass powder silica fume and scrapped ceramic waste on the mechanical properties of concrete

Carbon dioxide emissions from cement manufacture have a substantial environmental effect. The massive energy usage in the cement manufacturing process is also an issue. India is dealing with a major energy problem. Cement prices are rising on a daily basis. Furthermore, the usage of waste for the disposal and recovery of natural concrete components might harm the environment. Using trash not only decreases cement production and hence energy consumption, but it also helps to safeguard the environment. The goal of this study is to investigate the characteristics of concrete utilizing silica fume as a partial substitute for cement and glass powder in lieu of fine aggregate. These waste materials were used to replace some of the cement in the concrete samples, and their compressive, flexural, and split tensile strengths were assessed. According to the results, the addition of glass powder and silica fume improves the mechanical qualities of the concrete, but the addition of discarded ceramic waste has the reverse impact. Furthermore, the combination of glass powder and silica fume outperformed each waste item alone. The trials were carried out using Concrete Mix M40, which had been modified by substituting 40% of the coarse aggregate with waste ceramic aggregate, 20% of the fine aggregate with glass powder, and 10% of the cement with silica fume cement. Following tests of the concrete's compressive, split, and flexural strengths at 7, 28, and 28 days, the appropriate replacement dose was considered. The load-bearing capability of the beams is approximately the same as that of conventional beams throughout the board for the 20% replacement levels applied. The research comes to the conclusion that natural coarse aggregate may be used in place of scrapped ceramic aggregates (SCA) in concrete. Other beam specimens and typical beam specimens (CM) deflected more with load than a beam specimen with 10% SF, 20% GP, and 10% SCA. Modern technology allows for the production of lightweight, high-strength concrete at a low cost. When compared to CA, SCA lowered aggregate weight.

Effect of inclusion of natural pozzolan and silica fume in cement - based mortars on the compressive strength utilizing artificial neural networks and support vector machine

This study illustrates the effect of incorporating natural pozzolan (NP) and silica fume (SF) in cement-based mortars on the compressive strength. Up to 40% of the weight of cement in cement mortars can be replaced by NP powder. NP in its natural state can be used to replace up to 40% of the volume of sand in cement mortars. The replacement levels of cement by weight with SF are 5% and 10% to improve the mechanical properties of the NP-based cement mortars. Experiments were conducted to assess the compressive strength of cement mortars containing NP at 28 and 180 days of curing. The water/cement ratio was 0.49 for all the specimens. Models for the compressive strength of NP-based cement mortars and NP-SF-based cement mortars were formulated based on nonlinear regression analysis, artificial neural network (ANN) , and support vector machine (SVM) approach to explore the impact and exchanges of cement, NP, and SF mixtures. The RMSE of the nonlinear, ANN, and SVM models revealed that the RMSE of the ANN is significantly less than that of the nonlinear and SVM models. A sensitivity analysis for the predicted compressive strength of NP-based cement mortars and NP-SF-based cement mortars was conducted. The application of the SVM technique was evaluated through four different kernels, including sigmoid, linear, polynomial, and radial basis function (RBF). The RBF kernel shows better performance and offers more accurate results than the sigmoid, linear, and polynomial kernels. The results showed that the NP replacing cement and the SF replacing cement are the most dominant parameters for the prediction of compressive strength. Finally, the developed models from this study can be used to predict the compressive strength of cement mortars containing NP and SF.

Hydration characteristics, hydration products and microstructure of reactive powder concrete

Reactive Powder Concrete (RPC) is a new type of cementitious materials with a complex hydration mechanism, and active admixtures greatly influence the hydration reaction, formation of hydration products, and evolution of microstructure. In order to comprehensively study the quantitative effects of active admixtures contents, namely silica fume, slag and fly ash, on hydration characteristics, hydration products, and microstructure of RPCs, tests of workability, setting time, electrical conductivity, bound water and mechanical properties were conducted. Furthermore, a series of properties including morphology and micro-structure characteristics of RPCs were analyzed by thermogravimetric (TG) analysis, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), mercury intrusion porosimetry (MIP), Brunauer-Emmet-Teller (BET), and scanning electron microscope (SEM). The results indicate that the initial hydration reaction rate of RPCs is reduced by partly replacing cement with active admixtures. The pozzolanic effect created by the active admixtures enhances hydration and improves RPC's compressive and flexural strength. RPCs made of cement-silica fume mixture exhibit the best macroscopic properties. The adoption of silica fume promotes the production of C–S–H gel during hydration and exerts pozzolanic and crystal nucleation effects to promote cement hydration. RPCs made of pure cement exhibit 15.3% porosity after 28 days of hydration, with the largest proportion of less harmful pores in the microstructure. The porosity is reduced to 5.2% when cement is partially replaced with silica fume, and the microstructure is dominated by harmless pores. When replacement of silica fume is kept at 25%, using slag powder or fly ash substitute part of cement also reduces the number of less harmful pores. It is beneficial to add slag powder to increase the number of gel pores, whereas fly ash reduces the number of gel pores. The investigation presented in this paper would contribute to the production of low cost and environmentally-friendly RPCs, and accelerate the wider applications of ultra-high performance concrete (UHPC) in engineering structures.

Influence of recycled concrete aggregate enhancement methods on the change of microstructure of ITZs in recycled aggregate concrete

Recycled concrete aggregate (RCA) enhancement is an important method to improve the performance of recycled aggregate concrete (RAC). However, the quantitative studies on the change of microstructure of interfacial transition zones (ITZs) were few and far, especially after enhancement of RCA with different methods. This paper investigated the influence of carbonation enhancement (carbonation time, soaking in CH saturated solution and then carbonation) and chemical enhancement (respectively soaking in Na2SiO3 saturated solution and cement-silica fume (CEM-SF) slurries) of RCA on the change of microstructure of ITZs (including the ITZ between old aggregate-new paste (ITZ1) and ITZ between old paste-new paste (ITZ2)) in RAC. The porosity, the un-hydrated cement particles (UH) content, the volume fraction of hydration products (VFHP) in ITZs and the width of ITZs were obtained by backscattered electron imaging analysis (BSE-IA) and energy dispersive spectrometer (EDS) analysis. Results showed that the carbonation enhancement of RCA could not effectively strengthen ITZ1. However, soaking RCA in Na2SiO3 saturated solution and CEM-SF slurries could decrease the porosity and the UH content, develop the VFHP, and reduce the width of ITZ1, then strengthening ITZ1. Both carbonation and chemical enhancement could take obviously improvement on ITZ2. Additional calcium sources could be added to RCA by soaking in CH saturated solution, improving the effect of carbonation enhancement of RCA. Soaking in CEM-SF slurries had a better improvement effect on ITZs. After RCA was soaked in CEM-SF slurries, the porosity in ITZ1 and ITZ2 decreased by 36.8% and 44.0%, the UH content of ITZ1 and ITZ2 decreased by 22.6% and 53.6%, the VFHP of ITZ1 and ITZ2 increased by 22.6% and 20.9%, and the width of ITZ1 and ITZ2 decreased by 42.9% and 50%. EDS analysis showed that the Ca/Si atomic ratio of ITZs was reduced after RCA enhancement, which generated more hydration products and then decreased the porosity and the width of ITZs.

Early hydration and compressive strength of steam cured high-strength concrete based on simplex centroid design method

To obtain the precast concrete elements with high strength at an early stage, and strike a balance among mechanical properties, economic benefits and sustainable development. The heat of hydration, bound water content, calcium hydroxide content (CH), compressive strength and porosity of high-strength concrete (HSC) with cement–silica fume–fly ash micro-bead binder at 85 °C were investigated. The ternary binder formulations were the designed using simplex centroid design method. The results show that the appropriate amount of silica fume and fly ash micro-bead increases the total heat release and compressive strength of HSC, and reduce the CH content and porosity. Silica fume incorporation advances the induction period end time, while fly ash micro-bead increases the induction period end time. The pozzolanic reactivity of silica fume was greater than that of fly ash micro-bead. The effect of silica fume on 28 days strength was particularly obvious, and fly ash micro-bead have more significant improvement in early strength. The porosity shows a strong correlation with the compressive strength. The findings of this study are a worth reference for precast concrete manufacturers and can help to guide future studies.

Utilization of Silica Fume and Fly ash in Cement and Partial Substitution of Fine Aggregate Using Quarry Dust in Concrete

Thecemententerprisebetheessentialhotspotintendedfornaturalcontamination because it admissions a tremendous measure of energy during the creationas well as deliveries a ton of CO2which adds to an unnatural weather change. Reducethese impacts, concrete is to some degree subbed among the blend of Silica Fume (SF) and Fly Ash (FA) and sand by Quarry Dust (QD) with addition of steel fibre. This paper is centered on theconduct of substantial blend of M30 grade with particular of mechanical properties. Various mixes of rate substitutions of concrete by SF (5%) and FA (5%, 10%, 15%, 20%, 25%) and quarry dust (5%, 10%, 15%, 20%, 25%) with addition of steel fibre (1 %) were embraced for the making of mixed substantial blend. Test results indicated to facilitate the accumulation of silica fume and fly ash in cement and quarry dust in sand improved the compressive strengths of concrete.

Research on Cement Slurry Using Silica Fume Instead of Fly Ash.

Ordinary cement is not environmentally friendly, has high cost and lacks superior performance. Many scholars use various admixtures to adjust the properties of cement slurry, but admixtures are usually not environmentally friendly, and it is difficult to ensure that the properties after deployment meet engineering requirements. In this study, a variety of admixtures were obtained using the environmental protection method, and the optimal mixing ratio was analyzed by combining the entropy weight method and the Taguchi grey relational analysis method. The developed cement slurry was compared with conventional slurry from both macroscopic and microscopic aspects. Aiming at the problem that previous scholars lacked the engineering feasibility verification of the developed slurry, this study combined the constitutive equation regression analysis method, discrete element numerical simulation and other methods to study various actual engineering conditions. The results show that the optimal mix ratio of silica fume cement slurry has good permeability characteristics under the conditions of different roughness, grouting pressure and confining pressure. At the same time, under different geological temperatures and different erosive liquid states, the cement slurry stone body shows good properties of reinforcement materials.

Test and Mesoscopic Analysis of Chloride Ion Diffusion of High-Performance-Concrete with Fly Ash and Silica Fume

High performance concrete (HPC) is a kind of concrete with mineral admixtures, which has better resistance ability to chloride ions diffusion than ordinary concrete. In the present study, the authors carried out a chloride ion diffusion experiment for the HPC with fly ash and silica fume. The influence of the water–binder ratio (W/B), binary (Portland cement–Fly ash (PC-FS) and Portland cement–Silica fume (PC-SF) and ternary (Portland cement–Fly ash–Silica fume (PC-FA-SF)) combinations on the concrete compressive strength and chloride ion diffusion was investigated. It was found that the compressive strength of normal concrete and HPC increase with the decrease in the W/B, the ratio of W/B deceasing value to strength increasing value for normal concrete is 0.74, and for the HPC is 0.20, so the influence of the W/B on the concrete strength for normal concrete was obviously more than the HPC. The influence of the contents of the SF or FA on developing the concrete strength was limited. The concrete compressive strength of ternary combination specimens decreases with the increase in FA or SF when the content of the other mineral admixture SF or FA remained unchanged. The ternary combination was more efficient in prohibiting chlorides ingress insider the specimens than the binary combination. The mesoscopic simulation and the tested value of the chloride ion under the same depth was close, the average ratio of simulation value to tested value was 0.91. The aggregate shape and distribution also had a negligible influence on chloride diffusivity in the HPC, but the chloride ion concentration increased with the increase in aggregate size.

Enhancing the aggregate impact value and water absorption of demolition waste coarse aggregates with various treatment methods

Recycled aggregate (RA) from construction and demolition waste can readily be used to replace natural aggregate in concrete. Nonetheless, the poor quality of RA adversely affects the properties of recycled aggregate concrete, limiting its use to only non-structural applications. This study examined the effects of various treatment methods by testing the aggregate impact value (AIV) and water absorption (WA) of recycled coarse aggregate before and after treatments as an indicator to examine the efficiency of these treatments. The results showed that the untreated RA achieved 17% and 6.1% for AIV and WA, respectively. Accelerated carbonation treatment at 50% CO2 concentration level for six days of CO2 exposure time achieved the best results among other carbonation conditions, showing 11% and 46% enhancements in the AIV and WA, respectively. The RA treated with cyclic limewater combined with accelerated carbonation exhibited better improvement in the AIV and WA compared to the sole use of accelerated carbonation treatment. Coating RA with cement-silica fume slurry at 0.1 mm coating thickness was found to be optimal, achieving 12% and 54% enhancements in the AIV and WA, respectively. Soaking RA in a 10% Portland cement - pulverized fuel ash - silica fume solution for 4 h was found to be optimal, recording enhancements of 13% and 54% in the AIV and the WA, respectively among other soaking solutions. Soaking RA in 5% sodium silicate – silica fume solution for 4 h was found to be optimal, obtaining 8% and 33% enhancements in the AIV and the WA, respectively. The treatment techniques proposed can be a powerful tool for promoting the use of RA in the construction industry.

Synthesis and dispersing properties of organosilane-modified superplasticiser in cement–silica fume composite binder

The impacts of organosilane-modified polycarboxylate superplasticiser (OS-PCE) on the fluidity and hydration performance of a cement–silica fume (SF) composite binder were systematically analysed. It was found that the saturation adsorption amounts of OS-PCE on cement and SF were, respectively, 30.74% and 23.49% higher than those of ordinary PCE and the greater adsorption behaviour of OS-PCE contributed to higher fluidity of the cement–SF binder. The addition of OS-PCE retarded the hydration process of the cement–SF binder proportionally with the dosage of OS-PCE, but promoted the hydration kinetics of the composite binder. The enhancement in reactivity was attributed to well-dispersed SF by the OS-PCE, which provided more nucleation sites for the reaction of heterogeneous calcium silicate hydrates (C–S–H) and enhanced the contact with water to react with calcium hydroxide forming pozzolanic C–S–H. Well-distributed hydration products were identified in the hardened binder with added OS-PCE, with a large number of hydrated gels uniformly filling the pores and gaps, which densified the hardened structure.

Effect of Silica Fume on the Rheological Properties of Cement Paste with Ultra-Low Water Binder Ratio

The effect of silica fume on the rheological properties of a cement–silica fume–high range water reducer–water mixture with ultra-low water binder ratio (CSHWM) was studied. The results indicate that the W/B ratio and silica fume content have different effects on the rheological parameters, including the yield stress, plastic viscosity, and hysteresis loop area. The shear-thickening influence of CSHWM decreased with the increased silica fume content. When the silica fume content increased from 0% to 35%, the mixture with W/B ratio of 0.19 and 0.23 changed from a dilatant fluid to a Newtonian fluid, and then to a pseudoplastic fluid. When the silica fume content was less than 15%, the yield stress was close to 0. With the increase of silica fume content, the yield stress increased rapidly. The plastic viscosity and hysteresis loop area decreased slightly with the addition of a small amount of silica fume, but increased significantly with the continuous increase of silica fume. Compared with the Bingham and modified Bingham models, the Herschel–Buckley model is more applicable for this CSHWM.

Incorporation of Silica Fume and Waste Corn Cob Ash in Cement and Concrete for Sustainable Environment

This study has been done to make concrete mixtures more environmentally friendly by testing the performance of concrete mixtures that used recycled materials as a part of the Portland cement. As secondary cementitious materials (SCMs) like corn cob ash and silica fume were used to make concrete by replacing 15% of OPC. These materials are waste products from the agricultural and manufacturing industries. In this investigation, various test result has been performed on concrete containing corn cob and silica fume. The effects of the SCMs on the slump and mechanical characteristics of concrete were investigated. The result of this study shows that adding SCMs to concrete mixtures reduces the slump of the concrete mix. Tests results showed that 10% SCMs was found to be the best concentration for improving compressive and split tensile strengths. Using waste material like corn cob ash in concrete leads to eco-friendlier and more sustainable environment.

A comprehensive comparison between using silica fume in the forms of water slurry or blended cement in mortar/concrete

Silica fume (SF) is commonly used in concrete mixtures either in the form of water-based slurry or by using blended silica fume cement, each one having advantages and disadvantages. For instance, using SF blended cement has less issues regarding dispersion of SF particles, yet it limits the ration of SF content to the cementitious materials. Nevertheless, a holistic comparison between the effects of these two utilization forms on the properties of cementitious mixes is currently missing in the literature. In this research, a comprehensive comparison was performed between using SF in these two forms. For this purpose, the fresh properties, mechanical properties, dimensional stability, water permeability, and durability of mortar/concrete samples made with these two methods were assessed. The results showed that in general, SF blended cement samples had the same or slightly better performance compared to those made with SF slurry. Hence, utilization of SF blended cement could be a desirable alternative for SF slurry in construction projects.

Treatment of recycled concrete aggregate to enhance concrete performance

Recycled concrete aggregates (RCA) have received the attention of several researchers over the last few decades to overcome aggregate shortages and to push towards sustainable and environmental-friendly concrete. Nevertheless, utilizing recycled aggregates at a full replacement level may cause a reduction in its fresh, mechanical, and durability characteristics compared to concrete produced with normal coarse aggregates (NCA). This study aims at investigating the following influencing parameters: (a) four replacement levels of 0%, 33%, 67%, and 100% of recycled aggregate, (b) two maximum aggregate sizes of 10 and 20 mm, and (c) three treatment methods of (i) cement-silica fume slurry treatment (T1), (ii) sodium silicate solution treatment (T2), and (iii) Los Angeles (LA) abrasion treatment (T3). The test results revealed that the fresh properties of concrete were negatively impacted by the utilization of the untreated RCA, especially at higher replacement levels, irrespective of maximum aggregate sizes. The treated RCA with T1, T2, and T3 enhanced the concrete slump by 15%-35% compared to the untreated RCA. While the reduction in compressive strength for the untreated specimens was noticeable compared to the control specimens. The enhancement in the compressive strength for the treated RCA by T1, T2, and T3 was more pronounced regardless of the maximum aggregate size. The reduction in the water absorption for the treated RCA was clearly noticeable for the bigger aggregate size (20 mm) than that of 10 mm.

Mechanical Properties on Self - Compacting Concrete Replacement with Fly Ash, Silica Fume in Cement and Addition with Fibres

Self-compacting concrete has high workability and flow ability than normal compacted concrete. With its segregation resistance and fluidity, it offers a solution to problems in construction field like lack of skilled labour, inadequate compaction, over compaction, segregation etc. This study includes designing a self-compacting concrete mix which is standardized using its fresh properties with respect to EFNARC (European Federation of National Associations Representing for Concrete)standards. In this study, fly ash is used as partial replacement for cement in concrete. The mix design for M30 grade self-compacting concrete is done as per EFNARC standards. Then various properties of different mixes of M30 grade with 0%, 10%, 20%, 30%, 40% & 50%and 5% of silica fume as partial replacements of cement were compared, and the optimum percentage replacement is obtained at 30% replacement (SCC 30). On determining the optimum percentage replacement of fly ash in cement for M30 grade SCC as SCC 30, various properties such as weight loss and compressive strength and flexural strength of SCC 30 with normal SCC 30 are compared and then finally basalt fibres were added to cement content to asses the performance of concrete with fly ash and fibres as partial replacements of cement. It is found that the there is loss in weight as well as compressive strength and flexural strength of specimen due to adding fly ash and basalt fibres