Granulated Blast Furnace Slag Powder Research Articles

Pore Size Distribution and Surface Multifractal Dimension by Multicycle Mercury Intrusion Porosimetry of GGBFS and Limestone Powder Blended Concrete

Eco-friendly concrete mixtures make efficient use of constituents with reduced environmental impact to secure durable structures. Ternary mixes containing Portland cement, ground granulated blast-furnace slag (GGBFS) and limestone powder (LP) have demonstrated a good balance between environmental impact, economic cost and technical performance. The pore structure of cement-based materials determines the transport of species; hence its description is a valuable tool for predicting their durability performance. In this paper, textural analysis of the pore structure of Portland cement concrete and GGBFS and limestone powder blended concrete is assessed by multicycle mercury intrusion porosimetry (MIP). Results from three intrusion-extrusion cycles were used for determining pore volume, size distribution and surface multifractal dimension. The hysteresis during the experiments is mainly explained by the combined effects of ink-bottle pores and different contact angles for the intrusion and retraction. The analysis of the surface multifractal dimension of the pore structure showed no significant effects of GGBFS and limestone powder on the pore wall texture of concrete samples. The outcome depicts the advantages of using multiple intrusion-extrusion cycles during MIP experiments, as well as the effect of 35 wt.% GGBFS, 25 wt.% GGBFS + 10 wt.% LP, and 25 wt.% of LP, on concrete pore structure.

Study on the Influence of fly ash, mineral powder and silicon powder on the performance of high-performance concrete

To study the effect of fly ash, mineral powder, and silica fume on the working performance and mechanical properties of C70 high-performance concrete by adding the same amount of fly ash, granulated blast furnace slag powder, and silica fume as a composite admixture to replace the amount of cement. Influencing the law, at the same time, the optimal dosage ratio of various admixtures is determined through the orthogonal experiment. The results show that: when adding 6% silica fume, it can improve the performance of high-performance concrete. When the amount is increased, the viscosity of the concrete increases and the fluidity decreases. Incorporating an appropriate amount of silica fume can greatly increase the compressive strength of concrete. When blended with fly ash in the proportion of 20%, the performance of high-performance concrete is better. When the same amount of fly ash replaces cement, fly ash reduces hydration and improves the cohesion of concrete, 7d, 28d the compressive strength of the cube increases significantly. Adding 10% mineral powder, mineral powder can affect the early compressive strength of highperformance concrete, extend the setting time of concrete, and improve the pumping capacity of concrete.

Influence of boulder machine-made sand powder on compressive strength of concrete

In order to recycle the boulder powder produced in the process of manufactured sand production and reduce the cost of engineering concrete, this article studied the influence of boulders powder on the compressive strength of concrete. The results show that in the early stage of concrete test, the compressive strength of rock powder concrete is slightly lower than of fly ash and mineral powder concrete. With the development of curing age, the strength of boulders powder concrete developed slower. As the increase of boulders powder content, the compressive strength of different curing age gradually decreased, and it was suggested that the content of boulders powder should be controlled within 20% of cementitious materials mass. The positive effect of boulders powder fineness on the strength of concrete is limited, so it is suggested to use unprocessed collected boulders powder in the project, which is economical and environmentally friendly. With the adjustment of water-to-binder ratio, boulders powder can be prepared with different strength grades of concrete to meet the needs of engineering; the composite of boulders powder with traditional mineral admixtures, such as fly ash, and especially granulated blast furnace slag powder, can significantly improve the strength of concrete.

Preparation of sustainable and green cement-based composite binders with high-volume steel slag powder and ultrafine blast furnace slag powder

Abstract The mechanical properties and hydration mechanism of ultrafine ground granulated blast furnace slag powder (UFS)-cement-steel slag powder (SS) ternary cementitious material systems were studied. The chemical effects and contribution ratios of UFS and SS in ternary system at different hydration ages were also investigated. The results show that by adding UFS, the mechanical properties of concrete composites with high-volume SS conforming to the gap-graded particle size distribution are significantly enhanced. The close-packing effect between particles and the pore size distribution of hardened pastes are improved. The strength of cement matrix without any waste is still the highest. The SS has a negative impact on the hydration and strength development of the system at the early hydration ages, but it has a certain promoting effect at later hydration ages. UFS has a visible improvement effect on the hydration and the strength development of the system at both early and later hydration ages. The contribution ratio of UFS was analyzed and was found to be higher than that of SS apparently.

Research on the Influence of Carbonation on the Content and State of Chloride Ions and the Following Corrosion Resistance of Steel Bars in Cement Paste

In this paper, the changes of free chloride ion concentration and bound chloride concentration in cement paste with different total and proportion of mineral admixtures under carbonation were studied. Moreover, the following corrosion resistance of steel bars buried in cement paste under carbonation was researched by testing the electrical resistance and alternating current (AC) impedance spectroscopy of reinforced cement paste. Results indicated that fly ash and granulated blast furnace slag powder with the content less than 20% by mass ratio of total binder hindered the solidification of chloride ions in cement-based materials, and blast furnace slag powder with the content higher than 20% promoted the solidification of chloride ions in cement paste. The carbonation effect was able to decrease the amount of solidified chloride ion and increase the amount of free chloride ions leading to accelerating the corrosion of reinforcement. Meanwhile, the blast furnace slag powder with the content higher than 20% could effectively promote the corrosion resistance of steel bars.

Performance of slag-fly ash based alkali activated concrete for paver applications utilizing powdered waste glass as a binding ingredient

In the present scenario, there is a huge requirement of quality concrete for paver applications. The production of green and sustainable concrete has become a must to substitute the ordinary Portland cement (OPC) concrete. It is an eminent fact that the manufacture of OPC requires the burning of its raw materials which lead to a huge amount of carbon dioxide liberation; also, it requires a large amount of energy dissipation. The concrete produced using alkali activation has become renowned methods to replace the conventional OPC, which gives an answer to find a way to generate environmentally friendly concrete. In the current study, pavement quality concrete (PQC) is produced using alkali activation. The main focus of the work is to study the effect of powdered glass as a binding ingredient in Alkali-Activated Concrete (AAC) mixes. The alkaline activator used to activate the binder was sodium hydroxide solution dispersed in liquid sodium silicate. The utilization of industrial dissipate materials such as Ground Granulated Blast Furnace Slag (GGBS), fly ash, and waste glass powder was used as the binding ingredients, and stone crusher dust was used as fine aggregates. The experimental investigation showed that a PQC can be easily produced using alkali activation of industrial wastes satisfying its strength requirements. It was behaving better under fatigue, showing its relevance in usage as a pavement construction material.

Study on the Properties of High-Performance Ground Iron and Steel Slag Based on the Uniform Design

Ground iron and steel slag with excellent performance was prepared using the uniform test design. The influence of the fineness and content of steel slag powder on the fluidity and strength of the powder mortar was studied, the regression equations of fluidity and compression strength of different ages are derived, and the contour map is drawn. Based on the optimized composition, the bleeding and dry shrinkage properties and their application in slag concrete are evaluated; the results are compared with ground granulated blast furnace slag powder. The correlation coefficient between fluidity and compression strength of the mortar is more than 0.99, and the predicted value is in good agreement with the measured value, and the average relative error is less than 2%. Regression and isogram analyses show that an increase in the slag fineness and a reduction in its the content contribute to the improvement of the cementiting slag activity. The adequate composition is: steel slag (specific surface area: 520 m2/kg): 20%; blast furnace slag: 80%. Appropriate slag amount can significantly reduce the bleeding and dry shrinkage properties of mortar and optimize the microstructure of the interface transition zone of the concrete aggregate.

Insights into the properties and chloride binding capacity of β-hemihydrate in the presence of slag powder and white calcium aluminate cement

Calcium chloride (CaCl2) as a common concomitant in flue-gas desulfurization gypsum has a great negative impact on gypsum-based construction materials. Chloride binding in the form of Friedel's salt in the gypsum-dominating system is of great significance, but the feasibility of this approach has not yet been systematically clarified. In this paper, granulated blast-furnace slag (GBFS) powder and white calcium aluminate cement (CAC) were used as the components to explore their roles on the properties and chloride binding capacity of β-hemihydrate. Experimental results prove that CAC significantly improves compressive strength, water resistance, and chloride binding capacity of hardened paste. The XRD, DTG, SEM-EDS and thermodynamic modeling confirm that Friedel's salt forms in this system even at an early hydration time of 30 min. Mercury intrusion porosimetry and SEM results verify that the use of CAC decreases the volume of the pores in the 0.1–100 μm range. Thermodynamic modeling outcomes are consistent with the experimental data helping to explain the hydration and evolutions of β-hemihydrates in the presence of CaCl2, GBFS, and CAC at early hydration ages.

Steel fibre reinforced alkali-activated geopolymer concrete slabs subjected to natural gas explosion in buried utility tunnel

Accidental gas explosions in the buried utility tunnels around the world have caused massive losses in economy and human lives. The buried utility tunnel with adequate blast resistance capacity is therefore required to withstand the possible accidental gas explosions. In this study, a novel construction material, alkali-activated steel fibre reinforced geopolymer composite is introduced and the blast resistance capacity of slabs made of this material is studied in a full-scale buried utility tunnel. Fly ash and S95 grade ground granulated blast-furnace slag powder (GGBS) were used as the major binders in this geopolymer concrete. The plain geopolymer concrete had a compressive strength of 61 MPa and the steel fibre reinforced geopolymer concrete had a compressive strength of 74 MPa. The elastic modulus of the plain geopolymer concrete was found to be lower than the conventional C30 concrete. The methane gas explosion test was conducted in a full-scale (12 m × 1.8 m × 0.6 m) tunnel segment to investigate the structural performance of selected slab specimen (1.8 m × 0.4 m × 0.09 m). The test results and numerical simulations of structural responses subjected to methane gas explosion are presented. The results indicate the fibre reinforced geopolymer concrete slab has good capacity to resist methane gas explosion load.

Effect and characterization of the nucleation C-S-H seed on the reactivity of granulated blast furnace slag powder

It is still uncertain whether nucleation calcium silicate hydrate (C-S-H) seed can really improve the reactivity of granulated blast-furnace slag (GGBS) powder and accelerate the strength development. In this work, various pastes and mortars were prepared with cement, GGBS and C-S-H seed, and their compressive and flexural strengths, chemical shrinkages, the characteristics of hydration heat liberations and CH content in the hardened pastes, and reactivity indexes and reaction degrees of the GGBS in the presence of nucleation C-S-H seed were investigated. The results show that C-S-H seed notably increases the 1, 3, 7 and 28 d strength of the 50% GGBS and 50% cement mortar. The hardened pastes with nucleation C-S-H seed provide the greater strength reactivity index than the control at 7 and 28 d, especially 0.6, 1 and 2% C-S-H seed have more significant role on this index. It also enhances the chemical shrinkage and the more significantly increased chemical shrinkage is related to the higher content of nucleation C-S-H seed as the greater chemical shrinkage implies more hydration or reaction. It shortens the induction period, cut down the acceleration stage, accelerates the conversion of AFt to AFm and enhances the total hydration heat. It reduces the calcium hydroxide (CH) content in the hardened paste, and reaction degrees of the GGBS were investigated in order to further determine the role of nucleation C-S-H seed on the reactivity of GGBS, the results show that it improves the 1, 3, 7 and 28 d reaction degrees of GGBS, 1 and 2% C-S-H seed increase the percentages of the reacted GGBS at 1, 3, 7 and 28 d about 66% and 134%, 56% and 94%, 101% and 200%, 41.7% and 46.1% respectively by the control. These results will provide a reference for the more widely application of nucleation C-S-H seed as well as the activation of GGBS reactivity.

Experimental and numerical investigation of blast resistant capacity of high performance geopolymer concrete panels

In this study, the mechanical properties of a novel high performance alkali-activated geopolymer concrete under both static and dynamic loads were studied. The ground granulated blast-furnace slag powder (GGBS) and silica fume were used to manufacture this geopolymer concrete. Slabs that cast with this geopolymer concrete and steel wire mesh reinforcement were tested under close-in TNT explosion. The steel rebar reinforced C30 concrete slabs were tested as a control group. It is found that the steel wire mesh reinforced geopolymer concrete slabs achieved a more uniform strain distribution, which means a better structural performance against blast loadings as compared to the conventional C30 concrete slab under the same blast loads. The numerical investigation was then conducted to elaborate the test results.

Study on the characteristics of grout material using ground granulated blast furnace slag and carbon fiber

This study aims to evaluate the applicability of a grout material that is mixed with carbon fiber, biogrout, ground granulated blast furnace slag (GGBS) powder and cement. Uniaxial compressive strength tests were performed on homo-gel samples at days of 1, 3, 7, 14 and 28. In addition, the variation of permeability with the mixing ratios was measured. Based on the uniaxial compressive strength test, it was confirmed that the uniaxial compressive strength increased by 1.2times when carbon fiber increased by 1%. In addition, as a result of the permeability test, it was found that when the GGBS increased by 20%, the permeability coefficient decreased by about 1.5times. Therefore, the developed grout material can be used as a cutoff grouting material in the field due to its strength and cut-off effect.

Synthesis and Reaction Mechanism of an Alkali-Activated Metakaolin-Slag Composite System at Room Temperature

Synthesis of geopolymer using metakaolin (MK) usually requires a relatively high curing temperature, which limits the application of MK-based geopolymers in the practice of civil engineering. With the goal of developing a cementitious composite that can be cured at room temperature, in the present study, ground granulated blast furnace slag powder was incorporated into MK for the synthesis of a geopolymer. With the aid of compressive strength tests, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM), the influence of slag’s impact on the consistency, gelling time, and mechanical properties of the gelling system, as well as the reaction mechanism of the composite system, were investigated. The results showed that the incorporation of slag into MK improved the consistency of the slurry and shortened the setting time. A high-strength paste was synthesized successfully using the MK-slag composite system under ambient temperature curing. Results of XRD and FTIR analyses indicated that MK geopolymerization and slag hydration occurred simultaneously in the MK-slag composite system via alkali activation. The structure of hardened paste consists of both C-S-H-type and N-A-S-H-type gels. The activator module and the MK/slag mass ratio were the main factors affecting the strength of the synthesized products: when the slag replacement ratio was no more than 40%, the strength of the reaction products decreased with an increase of the activator module; when the slag replacement ratio reached or exceeded 60%, the strength of the reaction products increased with the increasing activator module.

Green quaternary concrete composites: Characterization and evaluation of the mechanical properties

Industrial byproducts such as fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and lime powder (LP), popularly known as supplementary cementitious materials (SCMs), have been extensively used in the manufacturing of cement and cement products in binary and ternary modes. In the present study, attempt has been made to develop a new sustainable green quaternary binder by partially replacing ordinary Portland cement (OPC) with different percentages of SCMs and find the optimum mix that can provide the best results in terms of mechanical as well as durability properties. The motivation is to reduce our dependency on OPC to reduce carbon foot print and utilizing these industrial byproducts for the sustainable development. Different compositions of quaternary binders were prepared and their physical, mechanical, and durability properties were studied and compared with the OPC and binary cement product pozzolanic Portland cement (PPC). The mechanical properties of concrete prepared with these OPC, PPC, and quaternary binders were also studied and it is established that the concrete mixtures prepared with quaternary binders provided better results and proved to be more economical. It is concluded that quaternary binders (a) OPC70% + FA15% + SF7.5% + GGBS7.5%, (b) OPC70% + FA15% + SF7.5% + MK7.5%, (c) 50%OPC + 30%FA + 10%SF + 10%GGBS, and (d) 50%OPC + 30%FA + 10%SF + 10%MK have produced relatively better strength, improved durability, and resistance to sulfate attack. These findings were also supported with the microstructural studies of hardened concrete of M20 grade using scanning electron microscope (SEM) and X‐ray diffraction (XRD).

Isothermal water vapour permeability of concrete with different supplementary cementitious materials

Water vapour permeability (WVP) is a key parameter for the sustainable thermal conditioning of buildings. The study of the WVP in concrete with supplementary cementitious materials (SCMs) allows for the design of structures with improved durability and sustainability. To our knowledge, there is insufficient experimental data in the literature regarding the WVP of concrete with SCMs. WVP tests were made on concrete mixes containing ground granulated blast-furnace slag (GGBFS) and limestone powder (LP) as a partial replacement for ordinary Portland cement, and of concrete mixes containing pozzolanic cement (NP). Results from three moisture gradients show that GGBFS induces the greatest reduction in WVP, followed by the NP. LP shows a diluting effect of the binder, which could be compensated by GGBFS in the ternary blend. From the comparison between the WVP and the capillary sorption rate, the influence of the SCMs on the connectivity of the smallest pores is assessed.

Analysis of Mechanical Properties of Self Compacted Concrete by Partial Replacement of Cement with Industrial Wastes under Elevated Temperature

Self-Compacting Concrete (SCC) differs from the normal concrete as it has the basic capacity to consolidate under its own weight. The increased awareness regarding environmental disturbances and its hazardous effects caused by blasting and crushing procedures of stone, it becomes a delicate and obvious issue for construction industry to develop an alternative remedy as material which can reduce the environmental hazards and enable high-performance strength to the concrete, which would make it durable and efficient for work. A growing trend is being established all over the world to use industrial byproducts and domestic wastes as a useful raw material in construction, as it provides an eco-friendly edge to the construction process and especially for concrete. This study aims to enlighten the use and comparative analysis for the performance of concrete with added industrial byproducts such as Ground Granulated Blast Furnace Slag (GGBFS), Silica fumes (SF) and Marble Powder (MP) in the preparation of SCC. This paper deals with the prediction of mechanical properties (i.e., compressive, tensile and flexural Strength) of self-compacting concrete by considering four major factors such as type of additive, percentage additive replaced, curing days and temperature using Artificial Neural Networks (ANNs).

Removal of Hexavalent Chromium in Portland Cement Using Ground Granulated Blast-Furnace Slag Powder.

Using ground granulated blast-furnace slag (GGBS) under different alkaline conditions, we studied the mechanisms and extents of Cr(VI) reduction and sorption and compared them to reactions with Portland cement (PC). We also investigated the effects of mixing PC/GGBS ratios on Cr(VI) dissolution after carbonating the substrates. We observed a complete sorption and reduction of Cr(VI) to Cr(III) in a GGBS-in-Ca(OH)2 solution (pH > ~12.5) after 10 h, whereas in distilled water (pH = ~11.5) GGBS exhibited only marginal sorption and reduction (20%). Cr reactions with dissolved ions in supernatants derived from GGBS indicated that the anions dissolved from GGBS act as a reducing agent for Cr(VI) in a Ca(OH)2 solution. Soft X-ray absorption microscopy identified a partial reduction of Cr(VI) to Cr(III) on the GGBS surface. The carbonation of pure PC paste substantially increased the amount of dissolved Cr(VI) in a solution phase whereas a 5 wt % replacement of PC with GGBS significantly reduced the amount of dissolved Cr(VI). We concluded that in the mixed paste during the early curing stage GGBS reduced a significant fraction of Cr(VI) to Cr(III) and that the Cr(III) adsorbed in the GGBS-PC mixture’s hydration products does not readily dissolve, even under carbonation conditions.

A study of high-performance slag-based composite admixtures

To promote the large-scale application of ground granulated blast furnace slag powder (GGBFS) in the cement and concrete industry, high-performance slag-based composite admixtures (SCAs) were prepared with GGBFS as the main raw material and converter steel slag powder (SS), limestone powder (LP) and fly ash (FA) as auxiliary raw materials. The effects of the fineness and content of each auxiliary raw material on the performance of the SCA were investigated. The experimental results showed that SS had multiple beneficial effects on mortar and concrete; it can increase the strength, reduce the bleeding and compensate for the shrinkage of the concrete. The best performance of medium- and low-strength concrete with a high SCA content was achieved using the SCA with the following composition: GGBFS: 64%; SS: 20%; LP: 6%; and FA: 10%. The fresh Portland cement (PC)+SCA concrete specimens had better fluidity and stability than the PC+GGBFS concrete specimen, and the compressive strengths of the PC+SCA concrete specimens were the same or slightly higher than that of the PC+GGBFS concrete specimen. The results of scanning electron microscopy, X-ray photoelectron spectroscopy and pore size analysis showed that the concrete specimens prepared with PC+SCA had significantly smaller and fewer large pores and a more uniform and dense interfacial structure than the concrete specimen prepared with PC+GGBFS. The exceptional performance of SCAs results from the advantageous synergistic effects of GGBFS and SS.

Improving the performance of architectural mortar containing 100% recycled glass aggregates by using SCMs

An experimental study was carried out to evaluate the mechanical and durability properties of architectural mortar prepared with 100% glass aggregates and using supplementary cementitious materials (SCMs) to replace cement. The mechanical properties were assessed in terms of compressive and flexural strength, whilst the durability characteristics were investigated in terms of drying shrinkage, resistance to high temperature exposure, alkali-silica-reaction (ASR) and acid dissolution.Experimental results suggested that strengths of glass-based architectural mortar incorporating SCMs (fly ash, ground granulated blast-furnace slag, metakaolin and waste glass powder) were comparable or even superior to that of the pure cement mortar when the cement replacement levels was up to 20%. In particular, waste glass powder (GP) as a pozzolanic material performed better than the other SCMs for flexural strength development of the glass-based mortar. The durability results also indicated that the addition of the SCMs could significantly reduce the drying shrinkage of the glass-based architectural mortar. All the recycled glass architectural mortars prepared with SCMs showed favorable resistance to expansion due to the ASR and less strength loss after heating to 800°C. GP and ground granulated blast-furnace slag (BS) blended mortars gave better performance below 600°C as compared to fly ash (FA) and metakaolin (MK) blended mortar. Also, the glass-based mortar containing GP exhibited the best performance of resistance to acid attack. Therefore, there is a potential to produce high performance architectural mortars with excellent mechanical and durability properties by reutilizing recycled glass to fully replace natural aggregates and partially replace cement.

Relationship among particle characteristic, water film thickness and flowability of fresh paste containing different mineral admixtures

This paper aims to study the influences of particle characteristic on flowability of cement paste containing different mineral admixtures. Fly ash (FA), ground granulated blast furnace slag (GGBS) and limestone powder (LS) were added by 10–30% of cement weight to prepare binary system. SEM observation, particle size distribution and packing density were carried out for every single and binary cementitious system. Fresh pastes of every cementitious system were prepared with variable solid volume fractions, and slump flow and flow times (T150, T200 and T250) were recorded in the mini-slump test to evaluate the rheological performance. The results show that the packing density of cementitious system is increased significantly by addition of LS due to the wider particle size distribution and decreased by addition of GGBS due to the irregular shape. FA has a little increasing effect on the packing density due to its finer and sphere particles. For different cementitious systems with similar particle shape, the closer to the Fuller distribution the particle size distribution, the higher the packing density is. The packing density of solid particles increases linearly with the lower n value of Rosin–Rammler distribution and the particle shape has little influence on this tendency. A flowable paste containing mineral admixture can be prepared with the higher threshold solid volume fraction and lower water film thickness (WFT) value. For every cementitious system, the relationship between the relative flow diameter (RFD) and WFT value can be described by the equation of RFD=b/(WFT+a)+c, and the relationship between flow time (T) and WFT accords with the equation of T=1/(d+e*WFT).