Use Of Ground Granulated Blast Furnace Slag Research Articles

Expansion due to alkali-silica reaction of ferronickel slag fine aggregate in OPC and blended cement mortars

About 14tonnes of granulated ferronickel slag (FNS) is produced as a by-product in the production process of 1tonne of ferronickel. The physical properties of FNS are suitable for its use as fine aggregates in concrete. This paper presents a study on the expansion due to alkali-silica reaction (ASR) of mortar bars containing different percentages of FNS aggregates originated from garnierite ore. Accelerated mortar bar test (AMBT) was performed to measure the expansion of the samples. FNS was found to be reactive in Portland cement mortar according to the AMBT results. Class F fly ash and ground granulated blast furnace slag (GGBFS) were used as the ASR mitigating measures of the FNS aggregate. Experimental results show that the use of GGBFS was unable to reduce expansion to the required level. However, the use of 30% class F fly ash as a supplementary cementitious material was found to be effective in reducing the 21-day ASR expansion below 0.3% required by the Australian Standard. Observations by scanning electron microscopy confirmed the effectiveness of fly ash in mitigation of the ASR products of FNS aggregates.

Performance of Ternary Binder Blend Containing Cement, Waste Gypsum Wall Boards and Blast Furnace Slag in CLSM

Controlled low strength materials (CLSM), is a self-flowing cementitious backfill material, most suitable for sustainability objectives since it makes use of wastes in large quantities. Wasted gypsum wall boards (drywalls), a construction & demolition waste, are known to pollute atmosphere by releasing harmful H2S gas when dumped at landfills. Use of waste drywalls with flyash, as cement replacement in concrete and CLSM, have resulted in low strength mixes at initial & later ages, respectively. In this paper powdered drywalls with ground granulated blast furnace slag (GGBS), was used as secondary cementitious material along with stone dust as fine aggregates, to produce sustainable CLSM mixtures with varying binder ratios and water contents. Reduction in compressive strength at later ages was not observed for mixes with low water contents, hence use of GGBS instead of flyash with lesser water contents, is effective in resisting detrimental effects of sulfates present in drywalls.

Assessing some durability properties of sustainable lightweight oil palm shell concrete incorporating slag and manufactured sand

This paper explores some of the durability properties of a sustainable concrete utilizing oil palm shell (OPS), which is a waste material from the palm oil industry, as lightweight coarse aggregate and manufactured sand to replace conventional natural mining sand as fine aggregate. Ground granulated blast furnace slag (GGBS) was used at 20%, 40% and 60% cement replacement levels with the aim of reducing the cement consumption in OPS concrete (OPSC) and the effect of the GGBS on the water absorption, sorptivity and the long-term free shrinkage of OPSC was investigated. The use of GGBS was found to reduce the sorption of OPSC as the 90-d sorptivity values fell in the range of 0.047–0.065 mm/min0.5, compared to 0.091 mm/min0.5 for mixes without GGBS. The OPSC containing GGBS was also found to have initial water absorption of below 3%, which indicated good quality of concrete. In the long term study, over a period of 365 d, the free shrinkage of the OPSC with up to 40% GGBS replacement level was comparable to the corresponding OPSC without GGBS. The GGBS was also found to be beneficial in enhancing the long term compressive strength gain as well as lowering the strength decrease of OPSC upon heat exposure.

The greenhouse gas implications of using ground granulated blast furnace slag as a cement substitute

The use of supplementary cementitious materials (SCMs) in concrete blends is often promoted as a way to reduce the environmental impacts of concrete. SCMs can include fly ash, silica fume or steel slag. Another SCM, and the focus of this paper, is ground-granulated blast furnace slag (GGBFS), which can be co-produced with pig iron. Previous studies that cite environmental benefits of GGBFS in concrete do not account for supply conditions of GGBFS. In this paper, this supply assumption is challenged through a market analysis. The environmental consequences of GGBFS supply conditions are assessed using a system expansion approach to life cycle assessment. When the supply of GGBFS is not constrained, greenhouse reductions of a given GGBFS-concrete blend are in the order of 47.5%. However, market analysis indicates that the supply of GGBFS can be constrained. Under a supply constraint, the 47.5% additional greenhouse reductions from the use of GGBFS are no longer applicable. Environmental certification schemes could ensure ongoing benefits of GGBFS by promoting the use of steel sourced from a supply chain which co-produces granulated blast furnace slag at the blast furnace.

Heat Transfer Characteristics of GGBS Concrete in Fire

Partial replacement of high clinker content cements by Ground Granulated Blastfurnace Slag (GGBS) can reduce the carbon footprint of concrete, with consequent benefits in respect of sustainable construction. Furthermore a state-of-the-art report indicated that use of GGBS as a binder replacement may increase the fire resistance of concrete. If so this could lead to thinner sections in fire compartment elements, especially non-loadbearing walls, leading to further gains in respect of sustainable development. Concrete is considered an effective material in protecting against the detrimental effects of fire in structures. However, exposure to high temperatures can degrade concrete performance. Fire resistance performance is typically defined relative to three failure criteria: load bearing resistance (R), insulation (I) and integrity (E). Heat transfer is a critical element of insulation and integrity performance. An experimental programme was developed to examine the potential beneficial influence of GGBS on fire resistance by examining the heat transfer performance of concrete, with and without GGBS. Test panels of concrete were subjected to heating to high temperatures. The panels included either limestone or sandstone aggregate, and a binder content of either CEM II/A-L only or a CEM II/A-L and GGBS combination at a cement replacement level of 70%. Concrete panels were heated in accordance with the standard fire curve of Eurocode 2. It was found that the heat transfer behaviour was in line with published data in the Eurocode for structural fire design. When exposed to elevated temperatures, such as those experienced in a fire situation, the performance of concrete containing GGBS exhibited a marginally lower rate of heat transfer than that of CEM II/A-L concrete. This resulted in a marginal improvement in the separating function (EI) performance. The marginally lower transfer of heat exhibited by GGBS concrete improved performance in terms of EI, such that a 5% reduction in the thickness of reinforced concrete separating elements could be considered. In addition, increased resistance to the effects of actions on a member, designed in accordance with the 500˚C isotherm ‘simplified’ method detailed in Eurocode 2, demonstrated a potential increased resistance of up to 10%. DOI: http://dx.doi.org/10.5755/j01.sace.8.3.7457

Effect of 30% Ground Granulated Blast Furnace, Lead and Zinc Slags as sand replacements on the strength of concrete

This paper investigates the effects of using Ground Granulated Blast Furnace Slag (GGBFS), Lead Slag (LS) and Zinc Slag (ZS) as replacement for sand on the strength of concrete. Compressive strength, flexural strength, water absorption and density were tested at 14, 28 and 56 days. In this study, a total of 40 concrete samples, including Pozzolanic Portland Cement (PPC), GGBFS, LS and ZS concretes, were produced with a water-to-cement ratio of 0.4, cement content of 400 kg/m3 and slag/sand replacement ratio of 30%. A superplasticizer was used in concrete at a proportion of 1.5% per weight of cement. The results show that the type of slag affects the mechanical properties of concrete. Compressive strength increased when GGBFS was used but decreased or remained unchanged when ZS or LS, respectively, were used as sand replacements in concrete. The results also demonstrated that the flexural strength of control concrete was higher than that of other mixtures. Dry density increased and water absorption decreased with the use of slags in concrete. In general, it can be concluded that the use of GGBFS and lead slag as fine aggregates in concrete is technically possible and useful in some cases, whereas the use of zinc slag has a negative effect on concrete.

Design of self-compacting concrete with ground granulated blast furnace slag

Ground granulated blast furnace slag (GGBS), due to its pozzolanic nature, could be a great asset for the modern construction needs, because slag concretes can be of high performance, if appropriately designed. The use of GGBS as a cementitious material as well as fine filler is being increasingly advocated for the production of High Performance Concrete (HPC), Roller Compacted Concrete (RCC) and self compacting concrete (SCC), etc. However, for obtaining the required high performance in any of these concrete composites, slag should be properly proportioned so that the resulting concrete would satisfy both the strength and performance criteria requirements of the structure. The present paper is an effort towards presenting a new mix design methodology for the design of self compacting GGBS concretes based on the efficiency concept. The methodology has already been successfully verified through a proper experimental investigation and the self compacting slag concretes were evaluated for their self compactability and strength characteristics. The results indicate that the proposed method can be capable of producing high quality SCC.

Technical and economic aspects of using GGBFS for crack control mitigation in long span reinforced concrete structures

In 2009, China accounted for half of the global steel production. As a waste material or by-product in the manufacture process, over 160 million tonnes of blast furnace slag is generated annually, of which only 55% is recycled. Blast furnace slag, ground to an appropriate fineness, can be used as a cementitious material in concrete. However, most ground granulated blast furnace slag (GGBFS) in China ends up in low-grade applications, including ‘low heat’ cementitious material used in low-grade bulk concrete and cementitious material in mortar.A recently started project at XJTLU aims to contribute to the application of GGBFS in long-span concrete structures in China by avoiding/reducing the use of more expensive crack control reinforcement. The use of GGBFS in long-span concrete structures in China is currently held back by the following:(1)Lack of awareness of the potential commercial benefits;(2)Concerns about the steady supply of GGBFS;(3)Difficulties in evaluating the mitigating effects of GGBFS on early-age “thermal loading”.This paper reports on the methodology which is adopted to carry out this project. Special considerations are paid to issues associated with concrete early-age thermal contraction. Modelling of a case study of a commercial building in Shanghai is used to compare the cost effectiveness of using conventional crack control steel reinforcement only with the mitigation of thermal crack stresses by adopting GGBFS as a partial replacement for traditional cement. The study includes the use of finite element modelling to investigate the development of heat during the early age cement hydration process and the resulting thermal stresses produced in the concrete.

Properties of self-compacting portland pozzolana and limestone blended cement concretes containing different replacement levels of slag

In order to reduce energy consumption and CO2 emission, and increase production, cement manufacturers are blending or inter-grinding mineral additives such as slag, natural pozzolana, and limestone. This paper reports on the results of an experimental study on the production of self-compacting concrete (SCC) produced with portland cement (PC), portland pozzolana (PPC) and portland limestone (PLC) blended cements. Moreover, the effect of different replacement levels (0–45%) of ground granulated blast furnace slag (GGBFS) with the PPC, PLC, and PC cements on fresh properties (such as slump flow diameter, T500 slump flow time, V-funnel flow time, L-box height ratio, setting time, and viscosity) and hardened properties (such as compressive strength and ultrasonic pulse velocity) of self-compacting concretes are investigated. From the test results, it was found that it was possible to manufacture self-compacting concretes with PPC or PLC cements with comparable or superior performance to that of PC cement. Furthermore, the use of GGBFS in plain and especially blended cement self-compacting concrete production considerably enhanced the fresh characteristics of SCCs.

Using slag for unfired-clay masonry-bricks

This paper reports on an investigation on the use of ground granulated blast-furnace slag (GGBS) in the development of a sustainable unfired clay binder material for stabilised masonry-brick. The compressive strength of the stabilised masonry-brick, using a semi-processed industrial kaolinite clay soil and a ‘real’ clay soil (Lower Oxford Clay) commonly used in masonry clay brick manufacture were examined. In practice between 1 and 3 wt.% lime is needed for modifying the soil properties and between 2 and 8 wt.% lime for stabilisation. Due to the high strength requirement in the building industry in comparison with stabilised highway pavement layers for example, a high maximum stabiliser dosage of 20% was used. However, only a small proportion of this high stabiliser content (20%) was lime or Portland cement. Cylindrical specimens were made at moisture contents of 25, 30, 35 and 40%, and cured for 28 days, before testing for unconfined compressive strength. Preliminary results show that the strength values for the stabilised clay systems investigated were within the strength range of 65 to 2077 kN/m2 at 28 days, with the lime–Portland cement blends tending to achieve lower strength values relative to the lime–slag blends. The results suggest that there is potential for the use of GGBS in unblended binders for the development of unfired clay masonry bricks.

GGBFS as potential filler in polyester grout: Flexural strength and toughness

The effectiveness of ground granulated blast furnace slag (GGBFS) as filler in polyester resin grout was investigated. The mix proportions of polymer grout was properly designed and manufactured. The binder, hardener and fillers used in this study were isophatalic unsaturated polyester resin (IUPR), methyl ethyl ketone peroxide (MEKP) and river sand as well as GGBFS respectively. The amount of GGBFS incorporated was varied from 10% to 30% of total filler by weight. The performance of the grout was investigated in terms of flexural strength development and durability. Modulus of elasticity test was also conducted in order to study the effect of GGBFS on toughness of the grout. Results were compared with the control grout without the slag as filler. The results showed that the use of GGBFS as filler has improved the performance of polyester resin grout. The grout has proven itself durable against the hostile environment of Malaysia and its performance were similar to that of epoxy resins but very much cheaper than the epoxy resin readily available in the market.

Selected engineering properties of concrete incorporating slag and metakaolin

The influence of incorporating ground granulated blastfurnace slag (GGBS) and metakaolin (MK) on concrete strength is investigated. Portland cement was partially replaced with 0–80% GGBS and 0–20% MK. The water to cementitious materials ratio was maintained at 0.5 for all mixes. The incorporation of MK causes an increase in strength, especially during the early ages of curing. However, the use of GGBS in concrete reduces the strength during the first 28 days. Beyond 28 days, the strength increases with the presence of GGBS up to 60% replacement. The decrease in compressive strength during the early ages of curing of GGBS concrete is compensated by the inclusion of MK. The presence of MK in concrete containing GGBS does not cause a decrease in the long-term strength.

Suppression of swelling associated with ettringite formation in lime stabilized sulphate bearing clay soils by partial substitution of lime with ground granulated blastfurnace slag (GGBS)

Ettringite related swelling in lime-stabilized sulphate bearing clay soil systems has only been reported within the last decade although similar expansive behaviour has been reported in concrete over many years. The use of ground granulated blastfurnace slag (GGBS), an industrial by-product, is well established as a binder in many cement applications where it provides enhanced durability and high resistance to sulphate attack. This paper reports on efforts to extend the use of GGBS to highway and other foundation layers by determining the beneficial effect of the suppression of swelling of lime-stabilized clay soils, particularly in the presence of gypsum. The paper describes the results of laboratory tests on lime-stabilized kaolinite containing different levels of added gypsum and on lime-stabilized gypsum (selenite) bearing Kimmeridge Clay to which, in both cases, the lime has progressively been substituted with GGBS. The tests determine the linear expansion behaviour of compacted cylinders, during moist curing in a humid environment at 30°C and during subsequent soaking in de-ionized water. The results illustrate that substitution of lime with GGBS produces significant reduction in linear expansion of lime-stabilized clay soils particularly those containing gypsum.

Effects of partial substitution of lime with ground granulated blast furnace slag (GGBS) on the strength properties of lime-stabilised sulphate-bearing clay soils

Increasing global awareness of environmental pollution as well as increasing waste material disposal legislation is providing impetus for material upgrading by stabilisation of in situ soil as an alternative to its export to land-fill and replacement by imported granular fill. The use of ground granulated blast furnace slag (GGBS), an industrial by-product, is well established as a binder in many cement applications where it provides enhanced durability, including high resistance to chloride penetration, resistance to sulphate attack and protection against alkali silica reaction (ASR). This paper reports on efforts to extend the use of GGBS to highway and other foundation layers by determining the beneficial effect on strength of progressively substituting GGBS for lime in lime-stabilised clay soils, particularly in the presence of gypsum. This paper describes the results of laboratory tests on lime-stabilised kaolinite containing different levels of added gypsum and on lime-stabilised gypsum (selenite) bearing Kimmeridge Clay to which, in both cases, the lime has progressively been substituted with GGBS. The tests determine the strength development of compacted cylinders, moist cured in a humid environment at 30°C. The results illustrate that substitution of lime with GGBS in stabilising gypsum-containing clays produces significant improvements in strength development. The process has important practical applications, and the paper reports on-going pilot field trials aimed at realising these applications.