Blast Furnace Slag Content Research Articles

Effect of blast furnace slag content on mechanical and slurry abrasion behavior of needle‐punched nonwoven fabric reinforced epoxy composites

AbstractThis article reports on mechanical and slurry abrasion response of a new class of material developed by reinforcement of blast furnace slag (BFS) in needle‐punched nonwoven polyester fabric epoxy composites. These epoxy‐based composites are prepared by the hand‐lay‐up technique with the variation of BFS content (0, 5, 10, and 15 wt. %) and at constant fiber loading. It is observed that the mechanical properties of the composites are improved significantly with the incorporation of filler. However, the properties like tensile, flexural and inter‐laminar shear strength are reduced beyond 10 wt. % of filler loading. Abrasive wear behavior of these composites is studied in the slurry environment by a slurry abrasion test rig (ASTM G105). The specific wear rate of composites under a steady‐state condition with respect to normal load and sliding velocity is found to decrease with the increase in filler loading. Further, experimental design through Taguchi's L16 orthogonal array is applied to determine the optimal parametric combination which reduces the wear rate. The parametric combination among sliding velocity of 0.93 m/s, normal load of 30 N, sliding distance of 600 m, silica sand size of 100 μm and filler loading of 5 wt. %, produces an optimum specific wear rate. The morphological study is conducted on abraded composite surfaces by using scanning electron microscopy (SEM) and possible wear mechanisms responsible for wear have been discussed.

Steel fibre reinforced geopolymer concrete (SFRGC) with improved microstructure and enhanced fibre-matrix interfacial properties

Geopolymers are aluminosilicate materials formed by mixing by-product materials with alkaline solutions, and which have several desirable properties compared to Portland cement concrete in terms of strength and durability. Most of the previous research on steel fibre reinforced geopolymer concrete (SFRGC) has focused on the properties of single or binary mixes hardened under heat curing conditions, which is a severe limitation for on-site, cast-in-place applications. In the current study, a novel plain and steel fibre reinforced geopolymer concrete (SFRGC), containing various types of commercial Silica Fume (SF) (densified, undensified and slurry silica fume) and varying Ground Granulated Blast Furnace Slag (GGBS) content in a ternary binder mixture, cured under ambient (room) temperature has been examined. An extensive experimental investigation was conducted to evaluate the fresh properties, mechanical characteristics and microstructure of the examined material. The experimental results indicate that the mechanical characteristics of all the examined mixes are enhanced by increasing the GGBS content, in both plain and steel fibre reinforced geopolymer concrete. Geopolymer concrete with undensified silica fume showed better mechanical strength compared to that with densified and slurry SF, due to the agglomeration and ineffective dispersion of the latter fume types. SEM microstructural observations and porosity measurements were also conducted. The results indicate that the inclusion of silica fume and increasing GGBS content leads to higher pozzolanic activity and pore infilling, providing relatively homogeneous, compact and dense microstructures and subsequently improved mechanical properties.

Electromagnetic Shielding Characteristics of Eco-Friendly Foamed Concrete Wall

The electromagnetic shielding characteristics according to the material composition of foamed concrete, which was manufactured to reduce environmental pollution and to economically apply it in actual building walls, were researched herein. Industrial by-products such as ladle furnace slag (LFS), gypsum, and blast furnace slag (BFS) were added to manufacture foamed concrete with enhanced functionalities such as lightweight, heat insulation, and sound insulation. The electrical characteristics such as permittivity and loss tangent according to the foam and BFS content were calculated and measured. Free space measurement was used to measure the electromagnetic shielding characteristics of the actually manufactured foamed concrete. It was confirmed that electromagnetic signals were better blocked when the foam content was low and the BFS content was high in the measured frequency bands (1–8 GHz) and that approximately 90% of the electromagnetic signals were blocked over 4 GHz.

Prediction of properties of fly ash and cement mixed GBFS compressed bricks

In the present study the artificial neural network is used to predict the properties of fly ash and granulated blast furnace slag mixed compressed bricks. Bricks containing fly ash, different proportion of granulated blast furnace slag with constant quantity of cement are fabricated. The bricks are cured by three ways such as, by sprinkling water, by dipping into the alkaline water, and by immersing into the acidic water for 3, 7 and 28 days respectively. After curing, the bricks are tested to determine its compressive strength, water absorption and pH. The results from the experiments were used for the training of the artificial neural network neurons. Using the trained artificial neural network, the values for the composition 0% to 60% were obtained with 5% increment in every interval. It is observed that as the content of granulated blast furnace slag increases than the fly ash content, the compressive strength increases. With the increase in granulated blast furnace slag content the water absorption reduces and pH increases and hence increases the resistance against acid attack.

高炉スラグ高含有結合材を用いたコンクリートの圧縮強度特性

Portland cement production dominates a major part of CO2 emission generated from construction materials and its reduction in terms of concrete is of particular significance. As a technical solution, the authors have been developing an HS concrete with a granulated blast furnace slag content as high as 65 percent for underground mass concrete constructions. In this paper, aiming at wider dissemination of massive HS concrete, the standard correction values of concrete compressive strength in structure (28SM91 value) were verified. The correction values of concrete strength in structure 28SM91 is 3N/mm2 through all season examined by statistics study.

The synergistic effect of nano-silica with blast furnace slag in cement based materials

The synergistic effect of nano-silica (NS) and blast furnace slag (BFS) have been studied. A constant water-to-binder ratio (w/b) of 0.5 was used for all mortars. The different dosage (10%, 20%, 30% and 40%wt) of BFS and 3%wt NS were added into cement. The results indicated that comparing with the reference BFS mortars without silica inclusion, incorporation of a small amount of NS in cement containing BFS increased 28days compressive strength, significantly. The incorporation of 3%wt NS in the cement pastes with 30%wt dosage of BFS have the highest compressive strength (59.42MPa). In the work, the heat of hydration, non-evaporable water content and pozzolanic activity of BFS were studied, and the results showed that NS has a negative effect on the hydration of BFS; Through the analysis of the total porosity and the pore size distribution, NS and BFS can significantly reduce the porosity of the cement matrix, and increase the density, which is also an explanation of the phenomenon of increased compressive strength.

Blended cements consisting of Portland cement–slag–silica fume–metakaolin system

In the present study, hydration of four-compound systems consisting of Portland cement and three supplementary cementitious materials : silica fume, blast-furnace slag, and metakaolin, has been investigated by means of isothermal calorimetry and thermal analysis. Substitution of Portland cement was achieved at 25, 30, and 35 mass% by cementitious supplementary materials. Owing to the high specific surface, the silica fume eventuated in more distinctive demonstration of pozzolanic reactions. It decreased C/S ratio and led to the formation of hydration phases with C/S ≅ 1, which is demonstrated by wollastonite crystallization at higher temperatures. Enhanced formation of gehlenite hydrate was proved by DTG when blended cements included higher content of metakaolin and blast-furnace slag. Pozzolanic materials increased the compressive strength of particular blended samples and thus overcame the dilution effect especially at long term of curing. Presented quaternary blended samples in comparison with ordinary Portland cement thus allowed the formation of more thermal stable hydration products and can be considered as promising materials for the development of special concrete also for hydrothermal applications.

MECHANICAL PROPERTIES OF CONCRETE INCORPORATED BFS AS PARTIAL REPLACEMENT OF CEMENT

The present research aims at developing special types of concrete known as Blast Furnace Slag Concrete by partial replacement of cement by Blast Furnace Slag (BFS) at different weight percentages (5, 15, 20, 30, and 40) %. The weight percentage was studied as it effects the physical and mechanical properties (density, compressive strength, flexure strength, dynamic modulus of elasticity, and quality factor). The results indicate that the density of concrete increases with BFS content increment, BFS enhanced the compressive strength, flexural strength, and the dynamic modulus of elasticity. On the other hand the quality factor is reduced with increasing slag addition. In general, the results indicated that the best result was observed at a replacement value of about 20% by weight.

The effect of high temperature on the design of blast furnace slag and coarse fly ash-based geopolymer mortar

Abstract In this study, geopolymer mortars were prepared by replacing blast furnace slag (BFS) based mixtures with coarse fly ash (FA) in different proportions. The aim of this study was to build a geopolymer mortar design for high temperatures using constant NaOH molarity (M) and constant curing temperature. In addition to 14 M NaOH solution and BFS as the binder material at a 60 °C curing temperature, double binder mixture ratios were prepared adding 25%, 50% and 75% FA. Geopolymer mortars with a liquid binder (L/B) ratio of 1 were subjected to oven curing for 5, 24, 48, 168 h. After physical and mechanical tests, the samples with the highest compressive strength were determined and six different mixtures with an L/B ratio in the range from 1 to 0.5 were prepared in order to increase the compressive strength of the samples in question. The physical and mechanical tests were repeated for the new samples. After the tests, the mortar sample with the highest compressive strength and its high temperature behavior was determined. For this purpose, the mortar sample with the highest compressive strength was subjected to temperatures of 200, 400, 600, 800 and 1000 °C, and changes in the physical and mechanical properties was analyzed. As a result of the experiments, the highest flexural strength value (3.6 MPa) was obtained from the mortar samples with a 25% BFS content subjected to curing for 5 h. The highest compressive strength values (27.3 MPa) were obtained from the mortar samples with a 100% BFS content subjected to curing for 48 h. In terms of compressive strength, the optimization of the L/B ratio resulted in a 28% increase (0.7) and this way, 35.1 MPa was achieved. Following the high temperature tests, 400 °C and 600 °C were determined as critical temperatures for changes in mechanical properties and changes in physical properties, respectively. However, the geopolymer mortars lost around 58% of strength at 1000 °C which is the final temperature.

A comparative cradle-to-gate life cycle assessment of three concrete mix designs

The concrete industry faces challenges to create concrete mix designs that reduce negative environmental impacts but also maintain high performance. This has led to ‘greener’ cementitious materials being developed which can decrease the use of traditional Portland cement (PC). This study intended to carry out a ‘cradle-to-gate’ life cycle assessment (LCA) on concrete mix designs containing different cementitious blends. The aim of this study was to obtain the overall environmental impact, with a particular focus on carbon dioxide (CO2) emissions of three concrete mix designs: CEM I (100 % PC content), CEM II/B-V (65 % PC content, 35 % Fly Ash (FA) content) and CEM III/B (30 % PC content, 70 % ground granulated blast furnace slag (GGBS) content). Evaluations of the three concrete mixes were performed using ‘SimaPro 8’ LCA software. A comparative cradle-to-gate LCA of these mixes has not currently been explored and could present a new insight into improving the environmental impact of concrete with the use of secondary materials. Recommendations from this work would help the industry make key decisions about concrete mix designs. Results show that Mix 2 (CEM II/B-V) and Mix 3 (CEM III/B) could potentially be taken forwards to improve their environmental impacts of concrete production. With respect to optimum mix design, it is strongly recommended that GGBS is selected as the addition of choice for reducing CO2 emissions. FA does still considerably improve sustainability when compared to PC, but this work proved that inclusion of GGBS environmentally optimises the mix design even further. Advantages of using GGBS include lower CO2 emissions, a substantial reduction of environmental impacts and an increased scope for sustainability due to the higher PC replacement levels that are permitted for GGBS. Due to mix designs enabling a higher contribution of GGBS additions, it would also indicate an increased positive effect regarding waste scenarios. The main contribution of this work demonstrated that concrete can be produced without loss of performance whilst significantly reducing the negative environmental impacts incurred in its production. The results obtained from this work would help to define the available options for optimising concrete mix design. The only material variations in each mix were the different cementitious blends. So, by determining the best option, a platform to make recommendations can be established based upon cementitious materials.

Effect of Ground Granulated Blast Furnace Slag and Polymer Microspheres on Impermeability and Freeze-thaw Resistance of Concrete

The primary objective of this study was to assess freeze-thaw resistance of concrete whose structure was modified by varying the water/binder ratio and ground granulated blast furnace slag content, and by air entrainment. The innovative method of the polymer microspheres-based air entrainment was used to provide a stable pore structure.Test results show that the method is very effective both in providing adequate air entrainment and in improving freeze-thaw resistance of concrete. All air-entrained concrete specimens with polymer microspheres (the spacing factor of ▪≤ 0.25mm) had a good resistance to the action of frost, regardless of the W/S ratio and the slag cement content.

Development of protective materials based on glass- and slag-containing portland cement structures

The effect of the glass powder of the broken container glass on the strength and corrosion resistance of protective materials based on the slag-containing Portland cement is investigated. Using the three-factor simplex-centroid experimental design, the optimization of structures of protective materials, bounded on the axis X1 by the content of granulated blast-furnace slag (GBFS) of 25–50 %, on the axis X2 – the amount of glass powder (GP) of 5–10 %, on the axis X3 – the changes in W/C of 0.24–0.3 is carried out. As a result, the optimum structure of the protective material comprising 40% of GBFS (X1 factor), 10 % of GP (X2 factor) at W/C=0.3 (X3 factor) is obtained. The material is characterized by a flexural strength of 6.5-8.1 MPa in the range of 2–28 days and the resistance coefficient of 1.38–2.1 after curing samples in corrosive environments for 60 days. A slight loosening of the surface layer of the protective material of the optimum structure in the environment of 5 % sodium sulfate solution due to the formation of the corrosion product – calcium sulfate is observed. The macrostructure of the stone chip of the investigated structure aged for 60 days in solutions of 5 % sodium chloride and sulfate was not affected. The approbation of the protective material of the optimum structure to determine its resistance to aggressive influences of an urban environment when restoring the damaged section of the reinforced concrete slab on the Kyivska Rusanivka railway halt is performed. It is shown that after 7 days of hardening in difficult weather conditions, no changes on the surface of the developed protective material, as well as gaps between the material and the concrete base were observed. The data obtained allow to recommend the developed material for restoring and protecting concrete and reinforced concrete structures of transport facilities in an aggressive urban environment, and also for improving the ecology of the region by recycling of broken container glass.

Silicon elution from three types of steel slag fertilizers in a paddy field analyzed by electron probe micro-analyzer (EPMA)

Elution of silicon (Si) from three types of slag fertilizers was tested in a paddy field. They were made from granulated blast furnace slag, dephosphorization slag and decarburization slag, respectively. Each fertilizer, embedded in epoxy resin to expose the cross section, was analyzed to get initial two-dimensional distribution images of Si, calcium (Ca), oxygen (O), magnesium (Mg), aluminum (Al), manganese (Mn) and iron (Fe) by electron probe micro-analyzer (EPMA). These resin specimens were set in a paddy field for 75 d. Then the second two-dimensional distribution images of Si, Ca, O, Mg, Al, Mn and Fe at the same site were analyzed again by EPMA. A comparison of the two-dimensional distribution images before and after setting in paddy field elucidated the following results: (1) Si eluted clearly from dephosphorization slag and decarburization slag; (2) Si, Ca, Mg and Al distributed homogeneously in granulated blast furnace slag. X-ray diffraction (XRD) clarified that granulated blast furnace slag was amorphous. The content of plant-available Si in each slag fertilizer was evaluated by the cation exchange resin extraction method. It was the highest in dephosphorization slag fertilizer. This result corresponded to Si elution from dephosphorization slag observed by EPMA. The content of plant-available Si was low in granulated blast furnace slag but high in air-cooled blast furnace slag. Although the content of plant-available Si in decarburization slag was low, the efficacy of Si elution was the highest in decarburization slag. From X-ray diffraction analyses, calcium silicate or larnite (Ca2SiO4) was considered to be the causative substance for efficient Si elution from decarburization slag and dephosphorization slag. Because of the high content of plant-available Si, dephosphorization slag and air-cooled blast furnace slag are recommended as silicate fertilizers in paddy fields.

Influence of Process Conditions on the Structure and Hydraulic Activity of Air-Cooling Blast Furnace Slag

Using the industrial limestone, fly ash and pure chemical reagents as raw materials, the blast furnace slag was prepared by the fast air-cooled method. Using orthogonal experiment method, the influence of process conditions such as heating rate, heat preservation time of the blast furnace slag in hearth, discharge temperature of slag and cooling speed on the glass content and hydraulic activity of blast furnace slag were studied, the main influence factors and the optimal process conditions of blast furnace slag were determined. The results showed that the discharge temperature of slag was the key factor influencing on the glass content of granulated blast furnace slag. The impact degree of all process conditions on the glass content of granulated blast furnace slag accord with the following sequence: discharge temperature of slag > heat preservation time > heating rate > cooling rate. And heat preservation time and cooling rate were the key factors influencing 28 days activity index of blast furnace slag, the impact sequence of all process conditions on the 28 days activity index of granulated blast furnace slag was as follows: heat preservation time > cooling rate > discharge temperature of slag > heating rate. This study also optimized the process conditions of granulated blast furnace slag for different indicators.

Influence of mineral admixtures on the electro-deposition healing effect of concrete cracks

Two types of solutions (ZnSO4, MgSO4) were selected to study the influence of mineral admixtures on the electro-deposition healing effect of concrete cracks. Four parameters (i e, rates of weight gain, surface coating, crack closure and crack filling depth) were measured. The mineral composition of electro-deposits in the cracks was analyzed. The study shows that the healing effect of mortar specimens with 10% fly ash is the worst, while the healing effect of mortar specimens with 20% fly ash is better than that of the specimens without fly ash. The rates of weight gain, surface coating, crack closure and crack filling depth decrease with increasing content of the ground granulated blast-furnace slag(GGBS). The mineral admixtures have no influence on the composition of deposits.

Preparation and characterization of glass–ceramic foams from blast furnace slag and waste glass

Glass–ceramic foams were produced by using blast furnace slag (BFS) and waste glass as raw materials, choosing TiO2, ZrO2, and CaF2 as nucleating agents, and adding CaCO3, Na3PO4·12H2O, and Na2B4O7·5H2O as a foaming agent, a foaming stabilizer and a flux agent, respectively. The effects of different BFS contents on the microstructure, bulk density, water absorption, and bending strength of the glass–ceramic foams were investigated. The results showed that glass–ceramic foams with 50wt% BFS exhibited excellent comprehensive properties (bulk density 0.79g/cm3, water absorption 2.71%, and bending strength 14.34MPa). The new development for preparation of glass–ceramic foams is a good way to recycle BFS and waste glass, so that it could create huge economic and environmental benefits.

Analysis of structural performance and sustainability of airport concrete pavements incorporating blast furnace slag

Abstract In this study, the effects of various blast furnace slag (BFS) contents on the performance of cement pastes and pavement were investigated at two levels, the micro and the macro. At the micro level, the strength and chemical properties of cement pastes containing various percentages of BFS and subjected to different water curing periods were evaluated. At the macro level, the structural and sustainability performance of airport concrete pavements were studied. In this regard, several structural design charts were developed to determine the thickness of the concrete slab required to withstand traffic loadings for various versions of aircraft design and subgrade strengths. The sustainability of the concrete pavements was assessed in terms of fuel requirements and greenhouse gas (GHG) emissions. In addition, a simple graphical method was proposed for comparing structural and environmental performance of concrete pavements with respect to BFS content, subgrade strength, different versions of the aircraft design, fuel requirements and GHG emissions for pavement construction. Based on the results obtained using the proposed method and the structural and sustainability analyses, scenarios are suggested for choosing preliminary BFS content.

Hydration of quaternary Portland cement blends containing blast-furnace slag, siliceous fly ash and limestone powder

In this study the hydration of quaternary Portland cements containing blast-furnace slag, type V fly ash and limestone and the relationship between the types and contents of supplementary cementitious materials and the hydrate assemblage were investigated at ages of up to 182days using X-ray diffraction and thermogravimetric analysis. In addition thermodynamic modeling was used to calculate the total volume of hydrates. Two blast-furnace slag contents of 20 and 30wt.% were studied in blends containing fly ash and/or limestone at a cement replacement of 50wt.%. In all cases the experiments showed the presence of C–S–H, portlandite and ettringite. In samples without limestone, monosulfate was formed; in the presence of limestone monocarbonate was present instead. The addition of 5wt.% of limestone resulted in a higher compressive strength after 28days than observed for cements with lower or higher limestone content. Overall the presence of fly ash exerts little influence on the hydrate assemblage. The strength development reveals that amounts of up to 30wt.% fly ash can be used in quaternary cements without significant loss in compressive strength.

Experimental investigation of glass content of blast furnace slag by dry granulation

Dry granulation, as a new process of molten blast furnace slag (BFS) treatment, is an attractive alternative to water quenching. The performance of BFS obtained from dry granulation must be assessed. The glass content, which is a significant factor to evaluate the performance of BFS as a replacement material for Portland cement, was investigated using the X-ray diffraction method. The results indicated that the glass content of BFS decreased as the slag droplet velocity was increased and decreased with an increase in the diameter of the slag particles. For a 2.04 m/s velocity and 0.80 mm diameter of slag particles, the value of the glass content is 94%, which is higher than the 91% content obtained from water quenching. To obtain much higher glass content, it is better to cool the molten BFS from a higher initial temperature. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 485–491, 2015

Processing and Wear Analysis of Blast Furnace Slag Filled Polypropylene Composites Using Taguchi Model and ANN

Abstract This paper analyses and reports on processing and solid particle erosion wear response of a new class of hybrid composites prepared by reinforcement of short glass fibers (SGF) in blast furnace slag (BFS) filled polypropylene (PP) matrix. In this investigation, composites with different BFS content (0, 10, 20 and 30 wt%) in a polypropylene matrix base, with and without 20 wt% SGF reinforcement, are prepared by injection molding route. To study the erosion wear response of these BFS filled composites, a plan of experiments based on the Taguchi technique is followed to acquire the wear data in a controlled way. This systematic experimentation has led to identification of significant process parameters and material variables that predominantly influence the erosion rate and also enables us to determine optimal parameter settings that lead to minimization of the erosion rate. An artificial neural network (ANN) approach is also implemented to predict the wear rate of the composites. The morphology of eroded surfaces is then examined by scanning electron microscopy (SEM) and possible erosion mechanisms are discussed. This study reveals that addition of blast furnace slag improves the erosion resistance of glass-polypropylene composites significantly and thus makes them suitable for tribological applications.