Furnace Slag Aggregates Research Articles

Effects on the Physical and Mechanical Properties of Porous Concrete for Plant Growth of Blast Furnace Slag, Natural Jute Fiber, and Styrene Butadiene Latex Using a Dry Mixing Manufacturing Process.

To evaluate the effects of industrial by-products materials on the performance of porous concrete for plant growth, this study investigated the physical, strength, and freeze/thaw resistances of porous concrete for plant growth, prepared by replacing cement with blast furnace slag powder at 60% by weight, and replacing natural stone aggregates with coarse blast furnace slag aggregates at rates of 0%, 20%, 40%, 60% and 100% by weight. In addition, the effects of adding natural jute fiber and styrene butadiene (SB) latex to these concrete mixtures were evaluated. The void ratio, compressive strength, and freeze/thaw resistance of the samples were measured. With increasing replacement rate of blast furnace aggregates, addition of latex, and mixing of natural jute fiber the void ratio of the concrete was increased. Compressive strength decreased as the replacement rate of blast-furnace slag aggregates increased. The compressive strength decreased after 100 freeze/thaw cycles, regardless of the replacement rate of blast furnace slag aggregates or of the addition of natural jute fiber and latex. The addition of natural jute fiber and latex decreased the compressive strength after 100 freeze/thaw cycles. The test results indicate that the control mixture satisfied the target compressive strength of 10 MPa and the target void ratio of 25% at replacement rates of 0% and 20% for blast furnace aggregates, and that the mixtures containing latex satisfied the criteria up to an aggregate replacement rate of 60%. However, the mixtures containing natural jute fiber did not satisfy these criteria. The relationship between void ratio and residual compressive strength after 100 freeze/thaw cycles indicates that the control mixture and the mixtures containing jute fiber at aggregate replacement rates of 20% and 40% satisfied the target void ratio of 25% and the target residual compressive strength of over 80% after 100 freeze/thaw cycles. The mixtures containing latex and aggregate replacement rates up to 60% satisfied the target void ratio and compressive strength.

Internal Curing of High-Strength Concretes Using Artificial Aggregates as Water Reservoirs

This paper investigates the shrinkage cracking performance of high-strength concrete (HSC) containing artificial fly ash (AFA) and artificial blast furnace slag aggregates (ASAs) used as water reservoirs to provide internal curing. Artificial aggregates (AAs) were produced through cold bonding pelletization of 90% fly ash or slag with 10% portland cement. At a constant water-cement ratio (w/c) of 0.28, a total of nine HSCs incorporating varying amounts of AFA or ASA (0%, 5%, 10%, 15%, and 20%) by total aggregate volume were designed. The hardened concretes were tested for compressive strength, splitting tensile strength, and modulus of elasticity at 28 days for assessment of mechanical properties. Drying shrinkage accompanied by water loss, restrained shrinkage, and autogenous shrinkage were also monitored for a drying period of 57 days. Test results indicated that the highest mechanical properties were achieved for HSC with 20% ASA. Using ASA extended the cracking time of the HSCs and resulted in finer cracks associated with the lower free shrinkage. Moreover, there was a marked decrease in the autogenous shrinkage for all HSCs including artificial aggregates.

고로슬래그 미분말과 순환잔골재를 사용하는 친환경 모르타르에 탈황석고 및 시멘트에 의한 품질향상

최근, 콘크리트 산업에서는 <TEX>$CO_2$</TEX> 배출량감소등 환경문제와 함께 부존자원의 고갈대책도 중요한 문제점으로 제기되어, 이를 동시에 해결하기 위하여 각종 산업부산물이나 산업폐기물을 콘크리트용 자원으로 재이용하는 방법이 연구되고 있다. 본 연구는 고로슬래그 미분말(BS)과 순환잔골재(RFA) 혼합 모르타르를 기반으로 하여 BS의 잠재수경성 반응을 탈황석고(FGD)와 보통포틀랜드 시멘트(OPC)의 자극반응으로 추가 활성화시킴으로써 일반 강도영역까지의 모르타르 활용성을 검토하고자 하였다. 결과적으로, BS에 FGD 10%, OPC 30%를 치환하고 RFA를 사용할 경우 OPC만을 사용하는 플레인 모르타르의 80%정도인 보통강도모르타르가 발휘되었지만 실용적인 측면에서 유동성적으로 플로치를 동일하게 유지하는 물-결합재를 낮춰 주게 된다면 더욱 플레인 강도영역에 근접할 수 있을 것으로 사료된다. As a solution of both environmental issue of reducing carbon dioxide emission and sustainable issue of exhausting natural resources, in concrete industry, many research on recycling various by-products or industrial wastes as the concrete materials has been conducted. The aim of this research is feasibility analysis of additional reaction with ordinary Portland cement and flue gas desulfurization gypsum based on the blast furnace slag and recycled fine aggregate based mortar to achieve the normal strength range. Consequently, in the case of mortar replaced 10% FGD and 30% OPC for BS, 80% of plain OPC mortar's compressive strength was achieved. Furthermore, when the water-to-binder ratio is decreased to keep the practically similar level of flow, it is expected to be achieve the equivalent compressive strength to plain OPC mortar.

Steel furnace slag aggregate expansion and hardened concrete properties

Steel furnace slag (SFS) is an industrial by-product that is not commonly utilized in bound applications because of its potential to contain high contents of free calcium and magnesium oxides, which expand when hydrated. In this study, a process was developed to quickly screen SFS aggregates for free oxide contents and expansion potential using complexometric titration, thermogravimetric analysis, and an autoclave expansion test. Two of the three SFS aggregate sources (high and low expansion) were selected for testing as a coarse aggregate in concrete. It was confirmed that SFS aggregates in concrete can produce acceptable strength properties, suitable freeze/thaw durability, and exceptional fracture properties. However, these SFS aggregates produced greater free drying shrinkage than concrete with dolomite aggregates. For SFS aggregates having low expansion potential, the hardened property tests indicate that SFS may be a suitable aggregate for concrete.

Use effects of blast furnace slag aggregates in hydraulic concrete

In this paper we present the effects of the incorporation of blast-furnace slag aggregates on the shrinkage, thermal conductivity and diffusivity, behavior at high temperature and durability in aggressive environments for concrete hydraulic basic blast furnace slag aggregates. The development of eco-mortar and eco-concrete could be an interesting field of application for waste recovery of blast furnace slag from Tunisian site or other sites steel production in North Africa.

Statistical models for the development of optimized furnace slag lightweight aggregate self-consolidating concrete

This investigation aims to develop robust lightweight self-consolidating concrete (LWSCC) mixtures with furnace slag (FS) aggregates. A factorial design was carried out to mathematically model the influence of three key mix design parameters on fresh and hardened properties of furnace slag LWSCC (FS-LWSCC) mixtures. The parameters were water to binder ratio (w/b), high range water reducing admixture (HRWRA) content and total binder content. The responses of the derived statistical models were slump flow, V-funnel flow time, J-ring flow diameter/height difference, L-box ratio, filling capacity, sieve segregation, unit weight and compressive strength. Twenty mixes were prepared to derive the statistical models, and ten mixes were used to verify the accuracy of the developed models. The models were valid for mixes made with 0.30–0.40 w/b, HRWRA of 0.3–1.2% (by total binder content), and 410 to 550kg/m3 of total binder content. The influences of w/b, HRWRA% and total binder content were characterized and analyzed using regression technique to identify the primary factors and their interactions on the measured properties. Utilizing the developed models, three optimum FS-LWSCC mixtures with high statistical desirability were formulated and tested. It was possible to produce robust FS-LWSCCs that satisfy European EFNARC criteria.

Influence of Blast Furnace Slag as Coarse Aggregate on Various Grades of Self Compacting Concrete

Self-compacting concrete (SCC) is a highly workable concrete that can flow through densely reinforced complex structural elements under its own weight and adequately fill all voids without vibration or mechanical consolidation. Effective use of industrial waste products in concrete gains many economic, environmental, and social benefits rather than disposing of it as waste. The objective of this study is to investigate the effect of blast furnace slag as a partial replacement for coarse aggregate in M20, M30 and M40 grades of fly ash blended self-compacting concrete. The coarse aggregate was replaced at a range of 30% by blast furnace slag aggregate and the various fresh and hardened concrete properties were determined and compared. From the results, it is recommended that 30% of slag aggregate can be effectively utilized for various self-compacting concrete applications.

Compressive strength of high strength class C fly ash-based geopolymers with reactive granulated blast furnace slag aggregates designed by Taguchi method

Compressive strength of geopolymeric specimens produced by class C fly ash and granulated blast furnace slag aggregates has been studied. Four different independent factors comprising of aggregate content, sodium hydroxide concentration, curing time and curing temperature were considered as the variables. To attain the maximum possible accurate responses by means of the smallest amount of examinations, Taguchi design of experiment method was followed. By taking into account three levels for each factor, 9 series of experiments were conducted on the specimens at 2 and 7days of water curing regime. For both considered regimes, a specimen with 30 weight percent of aggregate and sodium hydroxide concentration of 12M cured at 90°C for 16h had the highest compressive strength. On account of reactivity between aggregates and the fly ash, the compressive strength was reached to 69.3±5.3MPa and 76.2±3.6MPa at 2 and 7days of water curing, respectively. Fracture surface of specimens with the highest and the lowest strengths as well as effect of each considered factor on the compressive strength of the specimens were studied.

Radiation shielding properties of concrete with electric arc furnace slag aggregates and steel shots

Heavyweight concrete, prepared with a mixture of concrete and heavyweight aggregates or metallic components, is generally used for radiation shielding purposes. In the present study the radiation shielding properties of concrete prepared with electric arc furnace slag aggregates (EAFSAs) and steel shots, was investigated. The results indicated that concrete mixed with 50% EAFSA and 50% steel shots meets the weight and radiation requirements. The use of 50% EAFSA results in a decrease in the cost of concrete and also conserves a useful material, such as iron ore.

Properties of concretes with Black/Oxidizing Electric Arc Furnace slag aggregate

Abstract The aim of this work is to comprehensively investigate the possibility of partially substituting natural aggregates with Black/Oxidizing Electric Arc Furnace (EAF) slag in concrete production. Five recycled and one traditional mixes were produced to identify a convenient substitution ratio for the concrete. Main physical and mechanical properties of concrete containing EAF slag as aggregate according to Fuller’s grading curve were experimentally investigated. Chemical and durability tests were performed to study the microstructure and analyse the behaviour of the conglomerate exposed to detrimental agents. Results showed that high substitution ratios of coarse natural aggregates are possible without decreasing mechanical properties of concrete. Conversely, replacement of fine natural aggregates with recycled ones seems feasible at lower substitution ratios only. Presence of calcium and magnesium oxides in the slag does not seem to represent a limit for the durability of concrete, due to their stabilization in crystalline lattice.

Flexural Behavior of Reinforced Concrete Beams with Electric Arc Furnace Slag Aggregates

This study estimates the flexural performance of reinforced concrete (RC) beams with electric arc furnace (EAF) oxidizing slag aggregates. EAF oxidizing slag is a byproduct of steel production. It is composed mainly of CaO and SiO2, which are similar to the chemical properties of natural aggregates. Simply supported RC beams having various types of aggregates were tested to evaluate the applicability of EAF oxidizing slag as a concrete aggregate. The moment-curvature relationship and crack patterns up to peak load as well as the effective moment of inertia and deflection of the specimens under service load were analyzed and compared with the experimental results of natural aggregate specimens. The experimental results showed that the specimens with EAF oxidizing slag aggregates exhibited similar flexural performance to that of the specimens with natural aggregates.

Experimental Study of the Possibility to Make a Mortar with Ternary Sand (Natural and Artificial Fine Aggregates)

This experimental study investigates the possibility to make a mortar with a ternary sand (natural and artificial fine aggregates). This method is utilized to correct the particle size distribution of various sands used in mortar. For this investigation, three sands have been used: a dune sand (DS), a slag sand (SS), and brick sand (BS) at different proportions in mortar. After crushing, the artificial fine aggregate (blast furnace slag and waste brick fine aggregate) was sifted in order to use it as fine aggregate. The effect of the quality and grain size distribution of natural fine aggregate (i.e., DS) and artificial fine aggregates (i.e., SS and BS) on the physical properties of ternary sand confected (density, porosity, fineness modulus, equivalent sand, particle size distribution, water absorption) and properties of fresh and hardened mortar were analysed. In the same way for this study, the physical properties and chemical compositions of DS, SS, BS and cement were investigated. The results obtained show that the mechanical strength on mortar depends of the nature and particle size distribution of sand studied. The reuse of this recycled material (slag blast furnace and waste brick) in the industry would contribute to the protection of the environment. This study shows the potential of this method to make mortar with ternary sand (natural and artificial fine aggreagates) in order to improve the physical properties of sand. Utilising natural and artificial fine aggregates to produce quality mortar should yield significant environmental benefits.

Alkali-Activated Building Materials Based on Blast Furnace Slag and Non-Standard Aggregates

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Lightweight concretes of activated metakaolin-fly ash binders, with blast furnace slag aggregates

This work investigated geopolymeric lightweight concretes based on binders composed of metakaolin with 0% and 25% fly ash, activated with 15.2% of Na 2O using sodium silicate of modulus SiO 2/Na 2O = 1.2. Concretes of densities of 1200, 900 and 600 kg/m 3 were obtained by aeration by adding aluminium powder, in some formulations lightweight aggregate of blast furnace slag was added at a ratio binder:aggregate 1:1; curing was carried out at 20 and 75 °C. The compressive and flexural strength development was monitored for up to 180 days. The strength diminished with the reduction of the density and high temperature curing accelerated strength development. The use of the slag had a positive effect on strength for 1200 kg/m 3 concretes; reducing the amount of binder used. The thermal conductivity diminished from 1.65 to 0.47 W/mK for densities from 1800 to 600 kg/m 3. The microstructures revealed dense cementitious matrices conformed of reaction products and unreacted metakaolin and fly ash. Energy dispersive spectroscopy and X-ray diffraction showed the formation of amorphous silicoaluminate reaction products.

Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates

Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented.

Environmental Modeling of Blast Furnace Slag Aggregate Production

ABSTRACT The study presented in this paper has mainly consisted of developing an environmental model of the aggregate production process. An environmental assessment of blast furnace slag aggregates was performed at a given quarry site, for two typical production scenarios, with each yielding several gradings. The Life Cycle Inventory (LCI) of each grading was then determined for both scenarios. A considerable amount of production data could therefore be collected, and special attention was paid to calculating the energy consumed per ton of slag produced at the plant. These results have allowed comparing for the amount of aggregate produced: electric energy and fossil fuel consumption, the quantity of airborne emissions released, and solid waste production due to wear on quarry equipment parts. Both the production and grading scenarios are critical in terms of environmental assessment. The energy required to produce the smallest grading sizes (0/4, 4/6 and 6/10 mm) is actually about twice for one scenario over the other. As for coarser grading (10/14, 14/20 and 0/31.5 mm), energy consumption is 10 times less compared to the finer sizes. A small amount of waste is generated during slag processing. LCI fluxes will be discussed, given the scarcity of data available in the literature. Lastly, results reveal that a large amount of energy would be saved by using a more rational grading approach based on such environmental issues, along with the development of dedicated quarry models for local production optimization.

Production of high strength concrete by use of industrial by-products

Blast furnace slag aggregates (BFSA) were used to produce high-strength concretes (HSC). These concretes were made with total cementitious material content of 460–610 kg/m 3. Different water/cement ratios (0.30, 0.35, 0.40, 0.45 and 0.50) were used to carry out 7- and 28-day compressive strength and other properties. Silica fume and a superplasticizer were used to improve BFSA concretes. Slump was kept constant throughout this study. Ten percent silica fume was added as a replacement for ordinary portland cement (OPC) in order to obtain HSC. The silica fume was used as highly effective micro-filler and pozzolanic admixture. Superplasticizer at dosages of 2%, 1.5%, 1%, 0.5% and 0% by OPC weight for 0.30, 0.35, 0.40, 0.45 and 0.50 w/c ratios, respectively, were adopted. Results showed that compressive strength of BFSA concretes were approximately 60–80% higher than traditional (control) concretes for different w/c ratios. These concretes also had low absorption and high splitting tensile strength values. It is concluded that BFSA, in combination with other supplementary cementitious materials, can be utilized in making high strength concretes.