Silica Fume Research Articles

The preparation, property and hydration mechanism of ultra high performance concrete with metakaolin substitution for silica fume

In recent years, there has been a growing body of research on the use of metakaolin (MK) in Ultra-High Performance Concrete (UHPC) to address the issue of unstable production yields and quality of industrial by-product Silica fume (SF). However, the current scientific literature tends to focus primarily on performance enhancements, often neglecting to elucidate the underlying mechanisms responsible for these improvements. In this study, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), nuclear magnetic resonance (NMR), nanoindentation technology, and Mercury Intrusion Porosimeter (MIP) were employed to establish the correlation between mechanical properties and hydration products, microstructure, and micromechanical properties. The results indicate that the judicious addition of MK can enhance the Al/Si ratio, prolong the C-A-S-H chain length, thereby increasing the percentage of high-density C-A-S-H, reducing the volume of C-A-S-H gel pores, optimizing UHPC pore structure, and ultimately leading to improved mechanical properties.

Prediction of compressive strength of high-volume fly ash self-compacting concrete with silica fume using machine learning techniques

The quality and composition of the components in Self-Compacting Concrete (SCC) determine its compressive strength; however, determining these complex relationships through traditional statistical methods is difficult. This study uses five state-of-the-art machine learning techniques, namely, Random Forest (RF), Adaboost, Convolutional Neural Network (CNN), K-Nearest Neighbor (KNN), and Bidirectional Long Short-Term Memory (BI-LSTM), to simulate the strength properties of high-volume fly ash self-compacting concrete (HVFA-SCC) with silica fume. A database with 240 SCC compressive strength tests that included a range of material proportions was put together in order to train these models. The primary constituents that were selected and taken into consideration as input variables were cement, fly ash, super-plasticizer, silica fume, coarse and fine aggregate, and age. Various statistical metrics, regression error characteristics curve, SHAP analysis, and uncertainty analysis were used to validate the models' effectiveness in predicting the compressive strength of HVFA-SCC with varying material compositions. The recommended RF model demonstrated the highest predictive accuracy of all the models that were analysed. While machine learning can predict compressive strengths, its opaque 'black-box' nature limits its use for SCC mix engineers. This study introduces an open-source Random Forest-based GUI to close this gap. This interface helps engineers make mix proportion decisions by accurately estimating SCC compressive strength under various test conditions.

A Comprehensive Overview of Recycled Glass as Mineral Admixture for Circular UHPC Solutions

This review article analyzes the influence of recycled glass (as sand and powder) beyond the durability, rheology and compressive strength of plain UHPC, even exploring flexural and direct tensile performance in fiber-reinforced UHPC. Interactions with other mineral admixtures like limestone powder, rice husk ash, fly ash, FC3R, metakaolin and slags, among others, are analyzed. Synergy with limestone powder improves rheology, reducing superplasticizer usage. Research highlights waste glass–UHPC mixtures with reduced silica fume and cement content by over 50% and nearly 30%, respectively, with compressive strengths exceeding 150 MPa, cutting costs and carbon footprints. Furthermore, with the proper fiber dosage, waste glass–UHPC reported values for strain and energy absorption capacity, albeit lower than those of traditional UHPC formulations with high cement, silica fume and quartz powder content, surpassing requirements for demanding applications such as seismic reinforcement of structures. Moreover, durability remains comparable to that of traditional UHPC. In addition, the reported life cycle analysis found that the utilization of glass powder in UHPC allows a greater reduction of embedded CO2 than other mineral additions in UHPC without jeopardizing its properties. In general, the review study presented herein underscores recycled glass’s potential in UHPC, offering economic and performance advantages in sustainable construction.

Effect of hygroscopicity of typical powder solid wastes on their radon exhalation characteristics

The characteristics of radon exhalation in the hygroscopic properties of powder solid wastes are immensely significant for environmental safety and their transportation, storage, and landfill. This study detected the radon concentration of superfine cement and five kinds of powder solid waste: fly ash, silica fume, coal gangue, S95 mineral powder, and molybdenum tailing powder, at different hygroscopic times for 1–5 d under 95 % relative humidity. Additionally, the influence of particle size and porosity of solid waste on radon exhalation characteristics was analyzed using a laser particle size analyzer and nitrogen adsorption technology. The results show that the radon exhalation rate of the solid waste was at a low level in dry conditions. Although the presence of water due to the increased moisture absorption rate inhibited the radon exhalation to a certain extent, it was higher than that in dry conditions. The reciprocal of the moisture absorption rate had a strong linear relationship with the ratio between the radon exhalation rate after hygroscopy and radon exhalation rate from dry materials. The pore structure has a significant effect on the exhalation rate of radon, and the macropores inhibits the exhalation rate of radon. The results of this study have guiding significance for the reuse of solid waste and the prevention of radiation risk of radon exhalation during transportation.

Rheology of binary cement paste system blended with silica fume and alccofine

<p>The flow properties of the binary cement paste system added with supplementary cementitious materials, effect of polycarboxylate based superplasticizer dosage and their influence on the yield stress and the plastic viscosity were studied. The cementitious materials under the study are silica fume and alccofine. Both the plain cement and the binary cement paste system were considered and tested. A comparative study between the plain cement paste without any additions, silica fume blended cement paste and alccofine blended cement paste was performed. The addition of cementitious materials varies in the range 10%, 20% and 30% and the superplasticizer dosage varies in the range 0.5%, 1.0%, 1.5%, 2%, 2.5% and 3% in the mini-slump flow test and the saturation point was determined to be 2% in both the cases of silica fume and alccofine. The setting time and compressive strength testing on the cement paste considered the superplasticizer dosage up to saturation point. The flow characteristics are broadly the same among the binary paste systems. The setting time results indicated the increase in setting time with increase in cementitious additions and with increase in superplasticizer dosage. The higher percentage substitution of cement with silica fume and alccofine resulted in decrease in compressive strength due to the simultaneous acceleratory and retarding effects of cementitious additions and the superplasticizer. The results of the rheological measurements revealed that silica fume possess greater elasticity than that of the alccofine which possess greater yield stress and plastic viscosity.</p>

Enhancing mechanical properties of three-dimensional concrete at elevated temperatures through recycled ceramic powder treatment methods

To promote the construction industry and establish a green environment, the integration of sustainable building materials is urgently required. This study presents the influences of three materials (silica fume, fly ash, and recycled ceramic powder (RCP)) and different RCP dosages (0%, 10%, 20%, and 30%) on the mechanical properties and microstructure of concrete at different temperatures. The study presents the results of comprehensive flow tests, printability assessments, mechanical evaluations under different loading directions, high-temperature analyses, digital image correlation, X-ray powder diffraction and scanning electron microscopy. The experimental findings indicate the successful printing of all samples, with wall structure failure occurring only at a height of 730 mm. Furthermore, compared to those of other materials, the RCP displays a superior heat resistance, with a significant increase in compressive strength (28.9%) to 53.9 MPa at 300 °C. Additionally, the introduction of the RCP into 3D-printed concrete results in an anisotropic behaviour, with an initial enhancement in the mechanical strength, followed by attenuation as the RCP content increases. Microstructural analysis reveals enhanced interfacial adhesion with RCP addition, albeit accompanied by the emergence of numerous pores. The optimal mixture, which is designated as RCP-2-0-1 with 20% of the cement replaced by RCP, exhibits a significant anisotropic compressive strength (55.9 MPa) and an adequate anisotropic flexural strength (12.49 MPa) and impressive heat resistance (11.7% increase in compressive strength at 300 °C). This renders it a suitable sustainable impact-resistant thermal material for use in structural applications.

The phase changes of the mortars containing waste glass powder during carbonation

The utilization of glass powder (GP) with high pozzolanic activity to replace cement is a promising option for reusing waste glass. In such systems, Carbonation is a key factor that affects the durability. However, carbonation mechanisms remain poorly understood. In this study, the phase evolution of the GP - cement composites exposed to CO2 was determined by accelerated carbonation tests of samples with different cement-to-GP substitution rates (0, 15, 30, and 50 wt%). The carbonation depth was determined using phenolphthalein spray tests. Furthermore, the chemical information regarding the carbonation profiles was obtained by the X-ray diffraction (XRD), thermogravimetric analysis (TG), and Fourier transform infrared spectroscopy (FT-IR). It was found that an increase in the GP content increased the carbonation depth of the samples because of the low calcium hydroxide (CH) content. The increase rate was more similar to those of fly ash (FA) and silica fume (SF) rather than that of Ca-rich granulated blast-furnace slag (GBS). Moreover, XRD and TG tests revealed that compared to the plain cement, GP addition influenced crystalline forms of CaCO3, as well as the quantity of produced CaCO3. Combined with the FT-IR test results, when the replacement level of the GP up to ≥30 wt%, the produced CaCO3 and the depolymerised C-S-H by the carbonation significantly differed from the pure Portland cement. This study offers insights into the carbonation mechanisms of GP – cement mortars to promote glass recycling.

Construction of composites for medical purpose based on pyrogenic silica with immobilized succinic acid and their properties

The work is aimed at creating new, more effective drugs containing succinic acid. For this purpose, a methodology has been developed for transferring the active substance to a nano-sized state, in which the acid, due to an increase in its outer surface, is in the form of clusters, which, upon contact with the mucous membrane, can be more easily absorbed by the body. A complex of physicochemical methods was used to study the effect of immobilization of Succinic Acid (SA) on the surface of hydrophilic, hydrophobic silica and their mixtures on the existing specific surface area and the state of the adsorption layer. It has been shown that during the joint mechanical grinding of crystalline succinic acid with silicas, composite systems are formed in which it is uniformly distributed in the interparticle gaps of silicas and is in the form of nanosized predominantly amorphous clusters. For silicas and their mixtures, the signal of acid crystallites is also fixed on the X-ray diffraction patterns. Additional mechanical treatment of composites with water practically does not change the ratio of amorphous and crystalline components of succinic acid in the surface layer, which indicates its poor solubility in clustered water. This is also confirmed by liquid NMR data, according to which there is no signal from the methylene groups of succinic acid in the spectra. All composites, regardless of the content of SA, treatment with water, and the ratio of the hydrophobic and hydrophilic components, retain a high adsorption capacity with respect to nitrogen. The BET-specific surface of the composites remains at the level of 150 - 200 m2/g. Hydrated forms of hydrophobic silica AM-1 retain the ability to interact with non-polar substances. Using chloroform as an example, it was shown that even at h = 1 g/g, chloroform displaces part of the water from the interparticle space, which manifests itself in a decrease in the interfacial energy of water due to the formation of surface water clusters with a large radius. The hydrophobic silica surface stabilizes the weakly associated form of water, the amount of which can reach 20 mg/g.

Improving passing ability of ultra-heavy-weight concrete by optimising its packing structure

Heavy-weight concrete (HWC) is a widely adopted radiation shielding material in the nuclear industry. In this study, two kinds of high-density aggregate, namely, iron sand (IS) and steel slag coarse aggregate (SSCA), were adopted to fully replace river sand and natural coarse aggregate, respectively, producing ultra-heavy-weight concrete (UHWC) with a unit weight >3800 kg/m3, to ensure excellent radiation shielding performance. However, IS and SSCA seriously impaired the passing ability of UHWC as the cement paste could not hold the IS and SSCA as firmly as natural aggregates, owing to their high density. To overcome this, the rheology of UHWC should be optimised by partially replacing the cement with superfine silica fume (SSF) and using a suitable amount of superplasticiser (SP) to enhance the wet packing density (WPD). A total of 28 UHWC mixes with different replacement ratios of SSF and different SP dosages were tested for segregation width, flowability, L-box passing ability, unit weight and WPD. Results revealed that incorporating an appropriate quantity of SSF and SP improved the WPD of UHWC, resulting in improved segregation resistance, enhanced flowability, increased passing ability and a higher unit weight. Lastly, there is a positive correlation between flowability, passing ability and WPD.

Experimental Study on Performance of Fibre Reinforced Nanosilica Concrete

Nanotechnology offers promising enhancements to concrete, with nanoparticles augmenting its strength, workability, and durability. This study focuses on employing nano-sized cement as a replacement for conventional cement, particularly utilizing nano-silica due to its beneficial pozzolanic interaction with cement hydration products. Nano-silica effectively modifies concrete's durability by refining pore size and distribution. Experimental investigations reveal an optimal nano-silica replacement dosage of 1.5% to 3% b.w.c , beyond which efficacy diminishes. Further improvements are achieved by combining 0.5% nano-silica with 5% silica fume and varying percentages of aramid, steel, and polypropylene fibres. Notably, the inclusion of 0.1% steel, 0.2% polypropylene, and 0.03% aramid fibres by weight of volume, along with 5% silica fume and 0.5% nano-silica b.w.c , results in substantial compressive strength enhancements, as demonstrated by experimental findings. Key Words: Concrete, Nanosilica, Mixing Technique, Aramid, Compressive Strength.

The Durability of Concrete Mortars with Different Mineral Additives Exposed to Sulfate Attack

For several years, extensive research investigations have been conducted examining the effects of acids commonly encountered by industrial facilities in manufacturing environments. Numerous studies have been conducted to examine the durability of concrete containing various chemical additives and fine metals when exposed to various acid solutions, as well as the preventive steps taken to avoid the deterioration of concrete associated with these acids. This research includes an examination of enhancing the effectiveness and function of concrete when exposed to sulfuric acid. It explores the use of waterproofing (WP) and complementary cementitious materials (SCMs), including silica fume Nano silica and fly ash, as well as a water-reducing additive. Cube-shaped samples measuring 100 x 100 x 100 mm were prepared and completely immersed in 2.5% dilute sulfuric acid solution for 90 and 180 days. . Compressive strength, tensile strength, and absorption tests were performed after 28 days, as well as after immersion in a 2.5% dilute acid solution for 90 and 180 days. The results revealed that after 90 days, there was a 31% reduction in compressive strength for mixtures with 25% FA and 5% SF, and a 46% decrease for mixtures containing WP, when compared to their corresponding results at the 28 day age under standard conditions. Mineral admixtures significantly reduce absorption rates. After 90 days, WP had 3% absorption during acid exposure, and after 180 days, the 25% FA and 5% SF mixture had 2.3% absorption. This results from reduced permeable voids due to decreased capillary pores, enhancing concrete durability. The findings also indicated that the impact of exposure to acid on the strength characteristics of concrete becomes more pronounced with prolonged exposure. In addition, the inclusion of NS, SF, and FA in cement concrete results in the development of a unique material that can meet the growing need for construction materials. Furthermore, this technique delivers economic and environmental benefits by minimizing pollution caused by waste products such as FA and SF, which are a residual by-products of thermal power plants and ferrosilicon production respectively.

Effect of silica fume on the efflorescence, strength, and micro-properties of one-part geopolymer incorporating sewage sludge ash

The application of sewage sludge ash (SSA) in alkali activated cementitious material, i.e., geopolymer, was one of the effective measures to dispose of and recycle the sewage sludge. However, the geopolymer efflorescence could be aggravated due to elevated alkali content, especially for one-part geopolymer, where the dissolution reaction of solid alkali activator was less sufficient. This study focused on the efflorescence of GGBS-SSA based one-part geopolymer, as compared to two-part geopolymer, and the effect of silica fume on the efflorescence, strength and micro-properties of the one-part geopolymer. The results showed that the extent of efflorescence crystallization and the concentration of leached Na+ ions in the one-part geopolymer were more severe than the two-part geopolymer, due to the lower degree of geopolymerization reaction and the heterogeneous dense microstructure of the one-part geopolymer. After adding silica fume to the one-part geopolymer, the extent of efflorescence crystallization and the concentration of leached Na+ ions reduced significantly, and the compressive strength increased from 41.6 MPa to 57 MPa when the silica fume content was 10 %, but then decreased slightly. Adding the silica fume reduced the release rate of reaction heat, which helped to increase the solubility of solid alkali activator and improve the geopolymerization reaction, thus significantly reducing the content of mobile alkali ions and enhancing the compressive strength. Moreover, the silica fume with tiny spherical particle had better ball effect and micro-aggregate filling effect, which refined the pore size and reduced the connectivity of pore network, significantly reducing the diffusion rate and leaching of mobile alkali ions.

Study on performance and application of O-QGS soil curing agent for waste clay with low liquid limit

To reuse industrial solid wastes and waste clay with low liquid limit, a kind of soil solidification material by using cement, quicklime and industrial solid wastes such as ground granulated blast-furnace slag (GGBS), silica fume (SF) was developed in this study. Response surface methodology (RSM) based on central composite design (CCD) was used to design the experiment and optimize the mix ratio of GGBS, quicklime and SF under certain cement content conditions (i.e., the content ratio of cement, GGBS, quicklime, and SF was 5: 9.14: 1.7: 2.13). A soil solidification agent named O-QGS was developed to solidify waste clay with low liquid limit. To clarify the solidification mechanism of solidified soil, a series of laboratory experiments such as UCS test, water stability test, and scanning electron microscopy (SEM) test were carried out to capture the mechanical properties, water stability, and microstructure of O-QGS solidified soil and cement solidified soil. For practical purpose of O-QGS, a method for forming prefabricated pile by using O-QGS solidified soil was developed, and a method for strengthening soft foundations with prefabricated O-QGS solidified soil pile was proposed. Based on the results of load tests, the bearing capacity of prefabricated O-QGS solidified soil pile and cement high-pressure rotary jet grouting pile, as well as the composite foundations bearing capacity of prefabricated O-QGS solidified soil pile and cement high-pressure rotary jet grouting pile used for strengthening soft foundations, were analyzed. The feasibility of prefabricated O-QGS solidified soil pile used for strengthening soft foundations was verified in practice. The present study shows that the UCS of O-QGS solidified soil is 7.25 MPa at 28 days, and the water stability coefficient of O-QGS solidified soil is larger than 0.8. Compared with the method of cement high-pressure rotary jet grouting pile to reinforce soft foundation, the bearing capacity of prefabricated O-QGS solidified soil pile to reinforce soft foundation is higher, and the cost can be saved by 22.4 %.

Investigation of machine learning models in predicting compressive strength for ultra-high-performance geopolymer concrete: A comparative study

Ultra-high-performance geopolymer concrete (UHPGC) is a new category of traditional UHPC developed to meet the desire for ultra-high-strength and green building materials. In the current study, random forest (RF), support vector regression (SVR), and extreme gradient boosting (XGB) are used to forecast the compressive strength (CS) of UHPGC. Firstly, the findings of the 113 CS tests available in the previous studies were extracted. Twelve feature variables, including GGBS, silica fume, fly ash, and rice husk ash contents as precursors, the Na2SiO3, NaOH, KOH, and extra water content, polypropylene fiber, steel fiber, liquid-to-binder (L/B) ratio, and curing temperature, were investigated. After analyzing the extracted data, it was found that there were more mixtures of steel fiber-based UHPGCs and synthetic fibers compared to mixtures without fibers. This may reduce the accuracy and comprehensiveness of the predictive models used. To address this issue, several experiments were designed, performed, and tested. Overall, the dataset of 128 CS results was used to develop the machine learning (ML) models. The findings validate the effectiveness of the RF, SVR, and XGB models in accurately predicting the strength of the UHPGC, as constructed by their excellent predictive accuracy (R2 > 0.84). The XGB model performance is superior to the RF and SVR models. The feature importance analysis determined that the steel fiber content and L/B ratio were the top two elements that might profoundly impact the CS. Additionally, NaOH and silica fume also have a positive correlation with CS. Conversely, the extra water and percentage of GGBS exhibit a low correlation with the CS. Through the application of ML models, this study not only ascertains the significance of algorithms including RF, SVR, and XGB in precisely forecasting the CS of UHPGC, but also reveals essential understandings regarding the importance of steel fiber content, L/B ratio, and various other pivotal variables, consequently facilitating the development of refined formulations and improved functionalities in eco-friendly construction materials.

Improving the Mechanical Properties of Concrete Mixtures by Shape Memory Alloy Fibers and Silica Fume

Improving the Mechanical Properties of Concrete Mixtures by Shape Memory Alloy Fibers and Silica Fume

Reinventing concrete: Sustainable nano-alumina from metallic waste-cans and nano-ferrite for next-generation green magnetite heavyweight concrete

For the first time, sustainable nano-alumina, obtained from metallic waste-cans, is employed in green heavyweight magnetite concrete (GHMC). The GHMC mixes comprised fixed contents of 500, 125, 60, and 27.4 kg/m3 of cement, granulated blast furnace slag (GBFS), silica fume, and superplasticizer (SP), respectively. The benefits of typical magnetite heavyweight concrete was exploited alongside various percentages of research variables in different 11 mixes. The Sand (S) was used as a replacement for fine magnetite (FM) by (25 %, 50 %, 75 %), steel reinforced fiber (SRF) was added by (1 %, 1.5 %). Moreover, the nanoparticles included nano-Alumina (NA) by (2 %, 3 %, 4 %), nano-ferrite powder (NF) by 2 %, and 2 % NA+2 % NF. The effects of sand, SRF, NA, and NF were studied on slump, wet, dry, and oven dry densities, compressive strength (fc) and tensile strengths (ft), water absorption% (Wa%), electrochemical attack with chloride and sulfate, and thermogravimetric analysis (TGA), microstructure (SEM), and gamma-ray attenuation coefficient (LAC-μ, HVL, v) as shown in F ig. 1. The results revealed that adding 25 % sand, 1.5 % SRF, and 2 % NA+2 % NF boosted all of GHMC's tested properties. Although the replacement of 25 % sand slightly reduced the density of GHMC, it improved GHMC's workability, mechanical properties, and durability. Adding 1.5 % SRF resulted in an enhanced density as well as it improved all mechanical properties and durability. The fc, ft, and WA%, were enhanced by 31 %, 70 %, and 38 % at 28 days of age. The mixes incorporating 2%NA were better than those incorporating 2%NF for all testing properties. More improvements were noticed due to adding NA up to 4 %. Moreover, the mix incorporating 2 % NA+2 % NF had the best results compared to other nanoparticles percentages. For example, the dry density, fc and ft, and Wa% were improved up to 3.5 %, 66 %, 216 %, and 68 % at 28 days of age. Furthermore, the residual fc due to the exposure to chloride and sulfate was improved by 87 % and 78 % after 28 days, respectively. The TGA% at 1000 °C improved to 98.73 %, and LAC-μ improved by 83–102.4 %.

Development of ANN-based metaheuristic models for the study of the durability characteristics of high-volume fly ash self-compacting concrete with silica fume

The construction of durable and sustainable infrastructure requires the use of industrial byproducts such as fly ash (FA) and silica fume (SF) to enhance strength and durability. This study introduces novel machine learning models to forecast the results of rapid chloride penetration test (RCPT) for self-compacting concrete (SCC) containing high volumes of FA and SF. This study assessed the effects of supplementary cementitious materials (SCMs) and elevated temperature curing on the RCPT outcomes for SCC. Various metaheuristic algorithms including teaching–learning-based optimization (TLBO), ant colony optimization (ACO), the imperialist competitive algorithm (ICA), and shuffled complex evolution (SCE)—optimize the learning rate, weights, and biases of artificial neural network (ANN) models. A dataset of 360 experimental RCPT data points with seven input parameters was used to train and test the hybrid models. The accuracy of these models was assessed using eight performance indices, and the results were further analyzed through rank analysis, scatter plots, and error matrices. The training and testing sets for the AI models, specifically ANN-TLBO, exhibit a strong correlation between the experimental and predicted RCPT values, with R2 values of 0.9962 for training and 0.9676 for testing, compared to the R2 values of the other proposed models. Consequently, the results of this study suggest that the ANN-TLBO model is the optimal hybrid ANN model for predicting RCPT values in SCC. Verified experimental results and external validation indicate that the ANN-TLBO model is an effective alternative for accurately predicting real-time RCPT in SCC.

Use of pumice stone and silica fume as precursor material for the design of a geopolymer

Background Geopolymers are alternative materials to cement because they require less energy in their production process; hence, they contribute to the reduction in CO2 emissions. This study aims to evaluate the possibility of using industrial residues such as silica fume (SF) to improve the physical and mechanical properties of a pumice stone (PS)-based geopolymer. Methods Through an experimental methodology, the process starts with the extraction, grinding, and sieving of the raw material to carry out the physical and chemical characterization of the resulting material, followed by the dosage of the geopolymer mixture considering the factors that influence the resistance mechanical strength. Finally, the physical and mechanical properties of the geopolymer were characterized. This research was carried out in four stages: characterization of the pumice stone, design of the geopolymer through laboratory tests, application according to the dosage of the concrete, and analysis of the data through a multi-criteria analysis. Results It was determined that the optimal percentage of SF replacement is 10%, which to improves the properties of the geopolymer allowing to reach a maximum resistance to compression and flexion of 14.10 MPa and 4.78 MPa respectively, showing that there is a direct relationship between the percentage of SF and the resistance. Conclusions Geopolymer preparation involves the use of PS powder with a composition rich in silicon and aluminum. The factors influencing strength include the ratio of sodium silicate to sodium hydroxide, water content, temperature, curing time, molarity of sodium hydroxide, and binder ratio. The results showed an increase in the compression and flexural strength with 10% SF replacement. The geopolymer’s maximum compressive strength indicates its non-structural use, but it can be improved by reducing the PS powder size.

Analysis of the synergistic effects of micro silica on the mechanical and durability properties of geopolymer concrete incorporating phosphogypsum

Geopolymers are developed by activating aluminosilicates with alkali solutions, stand as inorganic cementitious materials. Their distinct advantages over Portland cement render them highly attractive in the pursuit of carbon neutrality. Moreover, the manufacturing of geopolymers results in notably lower CO2 emissions when contrasted with conventional cement production methods. The industrial byproducts fly ash (FA), phosphogypsum (PG) and micro silica (MS) contained the alumna and silica which can be used for the development of the geopolymer concrete (GPC). This study presents the various proportions of PG content, ranging from 8 % to 40 %, were utilized as a partial substitute for FA, along with MS proportions ranging from 2 % to 10 %, in the preparation of GPC. The alkaline solution was standardized at 12 M of NaOH, and the alkali-to-binder ratio was set at 0.45. The compressive strength, RCPT, sorptivity, water absorption and porosity tests have been conducted for the GPC. The maximum compressive strength of the GPC was 61.53 MPa obtained for FPM8. The compressive strength of the GPC rose with the increasing percentage of MS, peaking at 8 %. The porosity, sorptivity and water absorption were also resulted minimum for the mix FPM8. The scanning electron microscope (SEM) images show the presence of calcium alumino silicate hydrate (C-A-S-H) gel in the specimens, resulting in enhanced mechanical properties and heightened strength of the blended cement paste. The environment impact assessment analysis of the GPC also show that the developed specimens emit less carbon in comparison to the conventional concrete. Hence, the developed GPC from the FA, PG and MS can be used in the application of the sustainable construction work.

Preparation and Engineering properties of Slurry Infiltrated Fibrous Concrete (SIFCON) -A Review

This paper discusses the preparation of SIFCON and its important characteristics . Previous studies have shown that SIFCON has improved ductility , strength and durability . The paper also highlights different material that can replace cement ,such as silica fume ,fly ash with different percentage and different of steel fiber of over 4% can be used .Many previous investigation have shown that there is a significant relationship between the strength of concrete and the mortar and fiber mixture used in term of size and type .It has also been found that when using an amount exceeding 5% of fibers, certain steps should be followed in casting specimens . These steps including using fine sand less than 1 mm in size to create suitable cement slurry and replacing up to 30% of the cement with pozolana material to create cement slurry that can penetrate and interlock with fibers of all forms and volumes . Finally, the research offers a concise overview of concrete properties and their significance in addition analyzed the impact of fiber quantity increase on the density and various properties of concrete , including its compressive and tensile strength as well as energy absorption Additionally , its inspected how concrete responds to external element like exposure to sulfate attack , acids and fire.