Ultrafine Ground Granulated Blast Furnace Slag Research Articles

A critical review of slag and fly-ash based geopolymer concrete

Today, concrete remains the most important, durable, and reliable material that has been used in the construction sector, making it the most commonly used material after water. However, cement continues to exert many negative effects on the environment, including the production of carbon dioxide (CO2), which pollutes the atmosphere. Cement production is costly, and it also consumes energy and natural non- renewable resources, which are critical for sustainability. These factors represent the motivation for researchers to examine the various alternatives that can reduce the effects on the environment, natural resources, and energy consumption and enhance the mechanical properties of concrete. Geopolymer is one alternative that has been investigated; this can be produced using aluminosilicate materials such as low calcium (class F) FA, Ultra-Fine GGBS, and high calcium FA (class C, which are available worldwide as industrial, agricultural byproducts.). It has a high percentage of silica and alumina, which react with alkaline solution (activators). Aluminosilicate gel, which forms as a result of this reaction, is an effective binding material for the concrete. This paper presents an up-to-date review regarding the important engineering properties of geopolymer formed by FA and slag binders; the findings demonstrate that this type of geopolymer could be an adequate alternative to ordinary Portland cement (OPC). Due to the significant positive mechanical properties of slag-FA geopolymer cements and their positive effects on the environment, it represents a material that could potentially be used in the construction industry.

Geopolymers vs. alkali-activated materials (AAMs): A comparative study on durability, microstructure, and resistance to elevated temperatures of lightweight mortars

This paper studied the durability, microstructure, and fire behavior of lightweight mortars based on cement, metakaolin (MK), ultrafine ground granulated blast furnace slag (UGGBFS), ceramic waste powder (CWP), and clay brick waste powder (CBWP). Two sets of mixes were prepared with two types of lightweight aggregate including lightweight expanded clay aggregate (LECA) and pumice aggregate. Regarding the durability assessment, the electrical resistivity and water absorption of the mortars were measured. The UGGBFS-based alkali-activated mortar with pumice aggregate exhibited the highest electrical resistivity and lowest water absorption, while CBWP-based geopolymer mortar with LECA showed the lowest electrical resistivity, and the water absorption of this mortar was 62% higher than that of the equivalent cement mortar. In addition, scanning electron microscopy (SEM) images showed that UGGBFS-based mortar developed a dense matrix with few pores; whereas, incomplete geopolymerization and voids were detected in CWP- and CBWP-based mortars. Furthermore, the effect of elevated temperatures ranging from 23 to 800 °C on the compressive strength of specimens was investigated. According to the results, CWP- and CBWP-based mortars showed the best performance and retained about 54% and 49% of their original strength at 800 °C, respectively. Furthermore, a statistical study was carried out on the fire test results to quantify the contribution of different parameters using analysis of variance (ANOVA) method. It was shown that temperature was the most influential parameter.

Study on Compressive Strength of Geopolymer Concrete using Ultra-Fine GGBS for Ambient and Heat Curing

Study on Compressive Strength of Geopolymer Concrete using Ultra-Fine GGBS for Ambient and Heat Curing

Effects of ultra-fine ground granulated blast-furnace slag on initial setting time, fluidity and rheological properties of cement pastes

The initial setting time, fluidity and rheological properties of compound paste systems containing ultra-fine GGBS (UFS) were studied. The replacement of UFS into cement results in fast setting. An increase in the dosage of UFS shortened the initial setting time gradually due to the shortening of the induction period. Under the same UFS dosage, the induction period and initial setting time of the pastes was shorter in proportion to the fineness of the particles. The UFS showed a negative effect on the fluidity, and increasing the dosage of UFS gradually reduced the initial fluidity of the pastes. However, an interesting phenomenon was observed: for the same dosage of polycarboxylate superplasticizer (PCE), the initial fluidity was approximately the same as the increasing dosage of UFS. These results indicate that a possible positive synergistic effect on the initial fluidity was exerted due to the combination of UFS and the PCE, indicating that the UFS benefits the dispersing efficiency of PCE and the fluidity preservation of the pastes. The cement paste with UFS showed adverse effects on the rheological behaviour. The yield stress (τ0) and the plastic viscosity (ηp) increased with the rising dosage of UFS. Under the period of steady-state shearing (1800 s), the initial shear stress (τi) and minimum shear stress (τmin) increased consistently as the UFS content increased. However, adding PCE to the cement-UFS system resulted in rheological properties opposite to those of the pastes without PCE; the τi and τmin decreased as the UFS content increased. The results also confirmed the positive synergy effects between the UFS and the PCE.

Ultrafine GGBS and calcium nitrate as concrete admixtures for improved mechanical properties and corrosion resistance

This work reports the modification of ordinary Portland cement with ultrafine ground granulated blast furnace slag (GGBS) as a mineral admixture and calcium nitrate as a chemical admixture and examines how mechanical and corrosion properties are improved by this modification. Ultrafine GGBS with average particle size of 4–6 μM was introduced as a replacement mineral admixture (10%) to ordinary Portland cement while calcium nitrate was introduced as a chemical admixture at 2% amount of cementitious material, in the preparation of concrete. X-ray diffraction studies on powdered concrete showed that the amount of silica in the concrete increases with the introduction of GGBS. Calcium hydroxide was converted to calcium silicates. Ultrafine GGBS reduced the workability and water absorption and increased the compressive strength of the concrete (18%) and the bond strength of the steel rebar (45%). Adding calcium nitrate further reduced water absorption of the concrete but improved workability, compressive strength (32%) and bond strength (131%). The pH of the concrete powdered solution became more alkaline with the replacement of ultrafine GGBS and addition of calcium nitrate. Free chloride content dropped by 39% and 65%, respectively, with the introduction of GGBS and nitrate. Corrosion behaviour of the concrete specimens were studied using measurement of open circuit potentials, linear polarization resistance and Tafel polarization in an accelerated corrosion medium of 3.5% NaCl and 1 M sulphuric acid. Corrosion potential and current of the control specimens decreased with time for 40 days after which an increase was observed. Ultrafine GGBS shifted the corrosion potential in the cathodic direction, indicating retardation of the cathodic reaction (ex. oxygen reduction). Calcium nitrate, on the other hand, shifted the corrosion potential anodically by promoting the formation of a passive film of iron(III) hydroxide on the steel surface. Corrosion currents in GGBS and nitrate-modified concrete decreased by 200-fold compared to the control specimen on the first day, and by 480-fold on the 50th day (150-times smaller than the specimen modified with GGBS alone). Finally, scanning electron microscopy images of the corroded rebar at the end of 50th day indicate that pitting and intergranular corrosion occurs, with its extent reduced significantly by the introduction of admixtures. These results demonstrate that ultrafine GGBS and calcium nitrate as admixtures enhance the mechanical properties of concrete and reduce the corrosion of rebar.

Eco-friendly GGBS Concrete: A State-of-The-Art Review

Concrete is the most commonly used material in the construction industry in which cement is its vital ingredient. Although the advantages of concrete are many, there are side effects leading to environmental issues. The manufacturing process of cement emits considerable amount of carbon dioxide (CO2). Therefore is an urgent need to reduce the usage of cement. Ground Granulated Blast furnace Slag (GGBS) is a by-product from steel industry. It has good structural and durable properties with less environmental effects. This paper critically reviews the literatures available on GGBS used in cement concrete. In this paper, the literature available on GGBS are grouped into engineering properties of GGBS concrete, hydraulic action of GGBS in concrete, durability properties of GGBS concrete, self- compacting GGBS concrete and ultrafine GGBS are highlighted. From the review of literature, it was found that the use of GGBS in concrete construction will be eco-friendly and economical. The optimum percentage of replacement of cement by GGBS lies between 40 - 45 % by weight. New materials that can be added in addition to GGBS for getting better strength and durability also highlighted.

Utilization of fly ash and ultrafine GGBS for higher strength foam concrete

Foam concrete is a widely accepted construction material, which is popular for diverse construction applications such as, thermal insulation in buildings, lightweight concrete blocks, ground stabilization, void filling etc. Currently, foam concrete is being used for structural applications with a density above 1800kg/m3. This study focuses on evolving mix proportions for foam concrete with a material density in the range of 1200 kg/m3 to 1600 kg/m3, so as to obtain strength ranges that will be sufficient to adopt it as a structural material. Foam concrete is made lighter by adding pre-formed foam of a particular density to the mortar mix. The foaming agent used in this study is Sodium Lauryl Sulphate and in order to densify the foam generated, Sodium hydroxide solution at a normality of one is also added. In this study efforts are made to make it a sustainable construction material by incorporating industrial waste products such as ultrafine GGBS as partial replacement of cement and fly ash for replacement of fine aggregate. The fresh state and hardened state properties of foam concrete at varying proportions of cement, sand, water and additives are evaluated. The proportion of ultrafine GGBS and fly ash in the foam concrete mix are varied aiming at higher compressive strength. Studies on air void-strength relationship of foam concrete are also included in this paper.

Crumb Rubber Recycling in Enhancing Damping Properties of Concrete

Damping plays a major role in the design of roadside structures that gets affected due to vibrations transmitted from moving traffic. In this study, fine aggregates were partially replaced with crumb rubber in concrete, at varying percentages of 5, 10, 15 and 20% by weight. Three different sets of concrete, mixed with crumb rubber were prepared using raw rubber, treated rubber and treated rubber with partial replacement of cement. Cement was partially replaced with Ultra-Fine Ground Granulated Blast furnace Slag (UFGGBS) for this study. Samples were cast, cured and tested for various properties on the 7th and 28th day. The damping ratio and frequency of the peak value from a number of waves in rubber incorporated beams were found out using a FFT Analyser along with its Strength, Damping and Sorptivity characteristics. SEM analysis was conducted to analyse the micro structural bonding between rubber and concrete. The mode shapes of pavement slabs were modelled and analysed using a FEM tool, ANSYS. From the results, the behaviour of the three sets of rubberized concrete were compared and analysed, and an optimum percentage for crumb rubber and UFGGBS was proposed to achieve best possible damping without compromising the strength properties.

Experimental Investigation on Damping Property of Coarse Aggregate Replaced Rubber Concrete

Rubber has good damping and vibrational characteristics and can reduce cracking significantly due to its elastic nature. This property of rubber can be incorporated in concrete to control vibrations and create better pavements. Crumb Rubber on being dumped in landfills has serious repercussions and causes soil and land pollution. An innovative use of waste tires is shredding them into small pieces and using them as a replacement for coarse aggregate. Crumb rubber is obtained by chopping scrap tires, and in this study it was added in two different sets named SET 1 - Treated Crumb Rubber and concrete, and SET 2 - Treated Crumb rubber with Ultra Fine GGBS as admixture in concrete. Coarse aggregate replaces Rubber in each of the 2 SET’s in proportions of 5, 10, 15 and 20%. Properties like Compressive Strength, Young’s Modulus, Direct and Semi direct Ultrasonic Pulse Velocity, Sorptivity, Damping ratio and Frequency were found out. Deformation and mode shape were studied with modal analysis and static analysis by applying a uniform pressure corresponding to the highest compressive strength of the slab, using ANSYS.

Strength Studies of SCC Incorporating Silica Fume and Ultra Fine GGBS

The study of self-compacting concrete (SCC) denotes a field of exploration that shows a strong possibility of development due to its specific properties. The cost related with the utilization of vast volumes of concrete and synthetic admixtures is one of the significant disadvantages of SCC which can be redressed by the utilization of supplementary cementitious materials (SCM). Experimental investigation on the fresh and mechanical properties of SCC replacing cement with SCM such as silica fume and ultra-fine GGBS in 0%, 5%, 10% and 15% individually is carried out in this paper. SCC mix was obtained by fixing the water binder ratio and changing super plasticizer dosage with respect to total cementitious content. Incorporation of silica fume in 10% gave the best result in mechanical properties than any other combination with or without SCM.

Influences of Ultrafine Slag Slurry Prepared by Wet Ball Milling on the Properties of Concrete

The application of ultrafine ground‐granulated blast‐furnace slag (GGBFS) in concrete becomes widely used for high performance and environmental sustainability. The form of ultrafine slag (UFS) used in concrete is powder for convenience of transport and store. Drying‐grinding‐drying processes are needed before the application for wet emission. This paper aims at exploring the performances of concrete blended with GGBFS in form of slurry. The ultrafine slag slurry (UFSS) was obtained by the process of grinding the original slag in a wet ball mill, which was mixed in concrete directly. The durations of grinding were 20 min, 40 min, and 60 min which were used to replace Portland cement with different percentages, namely, 20, 35, and 50, and were designed to compare cement with original slag concrete. The workability was investigated in terms of fluidity. Microstructure and pore structure were evaluated by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The fluidity of concrete mixed with UFSS is deteriorated slightly. The microstructure and early strength were obviously improved with the grind duration extended.

Determination of fracture energy of ultra high strength concrete

In this paper, twenty-nine three-point bending beam specimens made of ultra high strength concrete (cube compressive strength of about 125MPa and cylinder compressive strength of about 105MPa) incorporating Ultra Fine Ground Granulated Blast-furnace Slag (UFGGBS) were tested. The depths of the beam specimens range from 75mm to 300mm. The fracture energy calculated by Hillerborg’s work-of-fracture method, Bazant’s size effect method, and Karihaloo–Nallathambi’s effective crack method, as well as two empirical formulas of Bazant and Becq-Giraudon and of CEB-FIP Model Code 1990 were investigated and compared on the basis of the tested specimens. It was found that the results from the different methods were different from one another. In addition, the authors introduce a nonlinear regression method based on the effective elastic crack model to calculate the fracture energy. It is shown that the proposed method shows good tolerance on the scattered test data, and thus leads to a more consistent fracture energy value.

Durability and mechanical properties of high strength concrete incorporating ultra fine Ground Granulated Blast-furnace Slag

Ground Granulated Blast-furnace Slag (GGBS) is a green mineral admixture that improves the rheology of fresh concrete, and its ultimate mechanical and durability properties. Ultrafine GGBS (UFGGBS) has increased surface area which increases the apparent rate of hydration, pozzolanic reactions and has a better filling effect. Two concrete mixes with 450 and 520kg/m3 of ordinary Portland cement and two more mixes of equivalent total cementitious materials with 30% UFGGBS replacement were cast. Compressive strength, flexural strength, modulus of elasticity, chloride migration, electrical resistivity and drying test results are presented. Concrete with UFGGBS has a higher early strength, lower permeability and improved durability even at 3days of curing.

Study on Ultra-Strength Mortar Prepared with Mineral Admixture

In this paper, preparation, property study of ultra-strength mortars with mineral admixture and clear river sand was carried out. The mineral admixture include fly ash, ultra-fine GGBS and silica fume. The experimental results show that the compressive strength of mortar improves with increasing amount of silica fume or ultra-fine GGBS. When the content of silica fume or ultra-fine GGBS is 30~35%, the compressive strength and flexural strength of mortar in curing age of 7 days are 100 MPa and 20MPa, respectively. But strength of mortar decreases with the increase replacement rate of fly ash. When the mortar mixes with combined of silica fume and ultra-fine GGBS, the optimum proportion of siliaca fume to ultra-fine GGBS is 2:3. And the compressive strength of mortar in curing age of 7 days is 75~100MPa when the mixed mineral admixture is 40~60%. The compressive strength of mortar is about 90MPa as it mix 60% of cement, 15% of silica fume, 15% of GGBS and 10% of fly ash. Moreover, the ultra strength mortar refines its pore structure and its capiliary pore (≥100nm) amount reduces by 78% compared to ordinary mortar.

A study on creep and drying shrinkage of high performance concrete

Creep and drying shrinkage are two important time-dependent properties of high-performance concrete (HPC). In this study, three groups of HPC with same mix proportioning except the type of binding materials were prepared. Their creep behaviour and drying shrinkage characteristics were measured in accordance with the Chinese Standard GBJ82-85. The effects of ultrafine ground granulated blast-furnace slag (GGBS) and silica fume (SF) on creep and drying shrinkage of HPC were compared and the mechanism was analysed.