Blast Furnace Slag Fine Aggregates Research Articles

Chemical Resistance of Concrete Using Blast Furnace Slag Fine Aggregate as Industrial Waste

Chemical Resistance of Concrete Using Blast Furnace Slag Fine Aggregate as Industrial Waste

Durability enhancement mechanism of mortar using blast furnace slag fine aggregate against combined deterioration of frost and salt damage

The effect of BFS (Blast Furnace Slag Fine Aggregate) on the freezing and thawing resistance under chloride environment was evaluated, and the freezing and thawing resistance was proven to be improved by using BFS with fine grain size and by increasing the mixing ratio of BFS to natural sand. The electrical resistivity and effective chloride ion diffusion coefficient were measured in order to evaluate the effect of BFS on the resistance of the penetration of chloride ions into concrete, and the mortar using BFS had higher electrical resistivity and lower effective chloride ion diffusion coefficient than the mortar using mountain sand. In order to elucidate the reaction products at the interface between cement paste and BFS, which cause densification of the BFS interface when BFS is used as fine aggregate in concrete, an investigation and analysis of the reaction products were conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As a result, it was found that a reaction phase is formed in the BFS-cement paste interfacial transition zone (ITZ), and its thickness is 0.45 to 1.4 μm. TEM observation and selected-area diffraction (SAD) analysis revealed the existence of hydrotalcite-like compounds in the BFS-cement paste ITZ. The chloride enrichment in hydrotalcite-like compounds at ITZ was confirmed by TEM observation and TEM-EDS of mortar with BFS after freeze–thaw tests under chloride environment. Therefore, it was considered to contribute to the improvement of the resistance of the penetration of chloride ions into concrete mixed with BFS.

Mechanical and durability properties of C–S–H-seeded cement mortar cured at fluctuating low temperatures with granulated blast furnace slag as fine aggregates

The conservation of natural resources, efficient use of industrial side-streams, and reduction of environmental impacts are the main targets of the construction sector worldwide. However, the low ambient temperatures and long harsh winter seasons in northern regions limit the use of industrial side-streams in construction activities under cold weather conditions due to their slow strength development rate. This study aimed to develop an eco-friendly construction material suitable for construction under cold weather conditions using blast furnace slag as a binder and fine aggregate admixed with a calcium silicate hydrate seed accelerator in mortar. Natural sand (NS) was volumetrically substituted with 25%, 50%, 75%, and 100% of granulated blast furnace slag (GBFS) fine aggregate in mortar cured at fluctuating low/freezing temperatures (+5 to −5 °C), representing the late fall and early spring seasons in northern regions. The mortar's compressive strength increased with the incorporation of GBFS aggregate over the first three days of curing and decreased thereafter. A denser interfacial transition zone was captured around GBFS aggregates than NS in the three days old mortars. The deceleration influences of fluctuating low/freezing temperatures on the compressive strength development of mortars were diminished with time. Capillary water absorption increased with higher GBFS aggregate contents. Mortar with 25–50 vol.% GBFS aggregates exhibited greater frost resistance than control mortar with NS only. The incorporation of GBFS aggregate enhanced the mortar's resistance against a sulfuric acid attack. This study demonstrates the potential of GBFS aggregate for use in construction under cold weather conditions.

Fundamental Study on Applicability of Blast Furnace Slag Fine Aggregate to Alkali Activated Material Mortar

Fundamental Study on Applicability of Blast Furnace Slag Fine Aggregate to Alkali Activated Material Mortar

Durability Enhancement Mechanism of Mortar Using Blast Furnace Slag Fine Aggregate Against Combined Deterioration of Frost and Salt Damage

Durability Enhancement Mechanism of Mortar Using Blast Furnace Slag Fine Aggregate Against Combined Deterioration of Frost and Salt Damage

Characteristics of Mortars with Blast Furnace Slag Powder and Mixed Fine Aggregates Containing Ferronickel-Slag Aggregate.

Recently, interest in environmentally friendly development has increased worldwide, especially in the construction industry. In this study, blast furnace slag powder (BFSP) and mixed steel fine aggregates were applied to cement mortars to reduce the environmental damage caused by the extraction of natural aggregate and to increase the recycling rate of steel by-products in the construction industry. We investigated the fluidity, compressive strength, tensile strength, accelerated carbonation depth, and chloride ion penetration resistance of mortars with steel slag aggregate and their dependence on the presence or absence of BFSP. Because the recycling rate of ferronickel slag is low and causes environmental problems, we considered mortar samples with mixed fine aggregates containing blast furnace slag fine aggregate (BSA) and ferronickel slag fine aggregate (FSA). The results showed that the 7-day compressive strength of a sample containing both 25% BSA and 25% FSA was nearly 14.8% higher than that of the control sample. This trend is likely due to the high density and angular shape of steel slag particles. The 56-day compressive strength of the sample with BFSP and 50% FSA was approximately 64.9 MPa, which was higher than that of other samples with BFSP. In addition, the chloride ion penetrability test result indicates that the use of BFSP has a greater effect than the use of steel slag aggregate on the chloride ion penetration resistance of mortar. Thus, the substitute rate of steel slag as aggregate can be substantially enhanced if BFSP and steel slag aggregate are used in an appropriate combination.

Strength and Durability Characteristics of Cement Composites with Recycled Water and Blast Furnace Slag Aggregate

Recently, interest in sustainable development has been increased. In this regard, efforts have been made to prevent environmental pollution, and research on the recycling of construction industry byproducts has been actively conducted in the construction industry. In South Korea, about 20 million tons of waste wash water from the ready-mixed concrete production process are generated, and some of them are recycled using recycling facilities in a ready-mixed concrete plant, but a significant portion of them is discharged or landfilled without permission, causing environmental problems. To increase the recycling rate of steel slag and reduce environmental pollution in the construction industry, we simultaneously applied blast furnace slag fine aggregate (BSFA) and recycled water (RW) to cement mortar. In this study, to examine the feasibility of RW and BSFA, we evaluated the fluidity, compressive strength, tensile strength, drying shrinkage, carbonation depth, and chloride penetration resistance of cement mortar using RW and BSFA. From the test results, the 28-day compressive strengths of all samples using RW and BSFA were higher than that of the control sample. In the case of samples using RW, as the BSFA replacement ratio was increased, the carbonation depth of the samples decreased. Therefore, when RW and BSFA are used properly, the mechanical properties of cement mortar, carbonation resistance, and chloride ion penetration resistance are expected to be effectively improved.

Effect of Superplasticizer Dosage on Compressive Strength and Microstructure of High Volume Basic-Oxygen Slag Mortar Exposed to Sea Water Attacks

The influence of superplasticizer addition on durability reinforcement of cement mortars made with basic-oxygen blast-furnace slag fine aggregate (BOF) as completely substitute for natural sand after being exposed to sea water solution for 6 months was evaluated by determining physico-mechanical characteristics in terms of water absorption and compressive strength in addition to microstructure analysis. In this procedure, all studied mixtures were doped with 1% and 2% superplasticizer. After the initial curing of samples in tap water for 28 days, they were subjected to sea water solution for 6 months using water to binder ratios of 0.35 and 0.45. The new hydration phases and microstructure of hardened specimens were identified by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results showed that cement mortars with slag fine aggregate blended with 2% SP offered better water absorption, compressive strength and microstructure than their counterparts with natural sand against sea water attacks. Therefore, they can be used in offshore structure applications.

Replacement Work of PC Slab with Concrete Using Blast Furnace Slag Fine Aggregate─Projects of Renewal Work of the Chugoku Expressway between Hokubo IC and the Oosa Smart IC

本技術は，プレキャストPC床版取替工事におけるコンクリート床版に高炉スラグ細骨材を用いることで，環境負荷低減と高い耐久性を併せ持つコンクリート構造物を構築するものである。本施工に先立ち，高速道路での実際の輪荷重を想定した荷重を載荷した場合の輪荷重走行試験を実施した。その結果，100年間使用する場合に必要な，輪荷重の繰返しに対する安全性が確保されていることが確認された。本稿では，高炉スラグ細骨材を用いたコンクリートの輪荷重走行試験の結果，ならびに現場施工の概要および実施工時に採集した試験体の耐久性試験の結果等を報告する。

Development of ternary blended rubberized cement mortar

Abstract The production of concrete has led to a major environmental issue with the production of cement has led to an equivalent CO2 emission in to the atmosphere, which is one among the green house gases. Secondly, the production of concrete with natural aggregates is a major challenge with the mining of silica sand from the river beds has led to an enormous environmental threat. In order to overcome these issues, M−sand obtained from the quarries has led to an effective replacement for river sand. In addition, the dumping of discarded waste tire from the vehicles in the waste land has led to an environmental degradation of the land which leads to pollution. In order to effectively utilize this waste tires, these can be effectively utilized as a partial substitution for M−sand in the construction sector. Hence, this work has been framed to investigate the effect of substituting cement with industrial byproducts such as ground granulated blast furnace slag (GGBFS) and silica fume (SF) and fine aggregate with crumb rubber at various replacement levels to assess the compressive strength of the ternary blended cement mortar.

Experimental investigation of monotonic behavior and stress-strain models of AE and non-AE high strength concrete with BFS fine aggregates under freezing and thawing

This study is attempted to investigate the change in mechanical properties and to formulate the stress-strain models of air-entrained (AE) and non-air entrained high strength concrete with blast furnace slag (BFS) sand as fine aggregates under freezing and thawing. The freeze-thaw (FT) test was carried out on the concrete specimens followed by static compression tests and the results are compared with those of AE normal strength normal (AENSN) and AE high strength normal (AEHSN) concrete using crushed sand. The experimental results disclose that overall the rate of plastic strain development due to freezing and thawing in non-AE high strength concrete is higher than that of AE high strength concrete, but less than that of companion normal strength concrete. Consequently, the mechanical properties of non-AE concrete deteriorate at higher rate in comparison with AE concrete under freezing and thawing. However, no significant reduction in mechanical properties of AEBFS and AEHSN concrete is observed compared to AENSN concrete. Moreover, it is found that the Young’s modulus of frost-damaged concrete degrades rapidly than the compressive strength. Thereafter, the stress-strain relationships for AE and non-AE high strength concrete under monotonic loading are formulated based on elasto-plastic and fracture concept. Based on the experimental data, the relationships for fracture parameter and plastic strain development of high strength concrete under monotonic loading are developed. The stres-strain relationships calculated by the proposed model are compared with the experimental ones.

Summary of Test Results of Blast-furnace Slag Fine Aggregate Concrete Cured in 20°C Water for 30 Years

Summary of Test Results of Blast-furnace Slag Fine Aggregate Concrete Cured in 20°C Water for 30 Years

Characteristics of the Concrete with Blast Furnace Slag Fine Aggregate and Fly Ash and its Applications

Characteristics of the Concrete with Blast Furnace Slag Fine Aggregate and Fly Ash and its Applications

Sulfuric Acid Resistance of Concrete with Blast Furnace Slag Fine Aggregate

Sulfuric Acid Resistance of Concrete with Blast Furnace Slag Fine Aggregate

高炉水砕スラグの粒度および密度に及ぼす製造条件の影響

The water granulation conditions for producing high density, coarse granulated blast furnace slag were investigated in a laboratory-scale experiment. The influence of the slag temperature, water temperature and nozzle shape on the density and grain size of the granulated slag was clarified. The influence of these factors on the density and grain size of the slag was confirmed by using various nozzles in the slag water granulation system.Neural network computation was applied to estimation of the density and grain size of granulated blast furnace slag. The influence of the water granulation conditions on the density and grain size predicted by neural network computation corresponded closely to the results of the laboratory-scale experiment.Based on the results of this research, we proposed a new slag granulation system and manufactured a high density, coarse blast furnace slag fine aggregate.

EXPERIMENTS ON THE STRENGTH DEVELOPMENT IN STRUCTURE SPECIMENS OF HIGH-STRENGTH CONCRETE USING THE BLAST FURNACE SLAG FINE AGGREGATE

In this experiment, the strength development in structure specimens of high-strength concrete using the blast furnace slag fine aggregate was studied. As results, it is less than specimens of standard curing that the proportion of mixing the blast-furnace slag fine aggregate influences the deterioration of strength about structure specimens. In period of curing, the temperature of concrete using blast furnace slag fine aggregate is slightly higher than concrete using sand in structure specimens. Strength correction value (S value) of the concrete using the blast furnace slag fine aggregate is smaller than the concrete using river sand in structure specimens.

Experimental Study on Mechanical Properties of High-Strength Concrete Using Blast Furnace Slag Fine Aggregate

In this experiment, blast furnace slag fine aggregate that was produced by 3 different steel factory was been used in high-strength concrete, and mechanical properties of high-strength concrete were studied. The concrete using the blast furnace slag fine aggregate is admitted the increase of compressive strength as well as the case of the river sand when the water cement ratio is reduced, and the compressive strength can attain 100N/mm2. The strength of concrete using blast furnace slag fine aggregate is lower than the strength of concrete using natural river sand as fine aggregate, and the strength of concrete using mixture fine aggregate is middle of strength used river sand and strength used blast furnace slag fine aggregate. The crushing value of blast furnace slag fine aggregate is bigger than the natural river sand, and it could influence the strength of high-strength concrete using blast furnace slag fine aggregate.

EXPERIMENTS ON COMPRESSIVE STRENGTH AND PORE STRUCTURE OF CONCRETE USED BLAST FURNACE SLAG FINE AGGREGATE

In this study, compressive strength and pore structure of concrete used blast furnace slag fine aggregates that was produced by 3 different steel factories and 1 type natural river sand as compared were examined, and the relationship between compressive strength and porosity was discussed. To concrete used blast furnace slag fine aggregates, compressive strength is lower and porosity is higher than concrete used sand at early ages. At long ages, compressive strength of concrete used blast furnace slag fine aggregates is higher and porosity is lower than concrete used sand when water cement ratio is 55%, but the compressive strength of concrete used blast furnace slag fine aggregates is lower when water cement ratio is below 40%. Young's modulus of concrete using the blast furnace slag fine aggregate is higher than concrete used sand. The relationship between compressive strength and porosity of concrete used blast furnace slag fine aggregates is very consistent with common strength-porosity equation about concrete as well as the concrete used sand.

INFLUENCE OF EXTERNAL FACTORS ON LEACHING OF HEXAVALENT CHROMIUM FROM CONCRETE WASTE

In this paper, the influence of the external factors on the amount of hexavalent chromium Cr(VI) released from the concrete waste and the adsorption/reduction action caused by the surround soil, was investigated. The following results were obtained.1. Serial batch test using mildly nitric acid solution is expected to be able to assess available amount for leaching under the general environment.2. In case of the carbonation sample, the dissolution continued under the soaking condition, after the 91 days.3. Blast-furnace slag fine aggregate and the powder reduced Cr(VI).4. Volcanic cohesive soil and organic soil have the capacity of absorption/reduction.

高炉スラグ細骨材用固結防止剤の開発

良質な天然砂の採取が困難なことに加え, 最近では, 環境悪化への懸念から海砂を中心に, 天然砂の採取が規制されている。天然砂の代替に, 高炉水砕スラグを破砕し, 粒度調整した高炉スラグ細骨材がコンクリートに使用されている。しかし高炉スラグ細骨材には水硬性が有り, 貯蔵時の温度や期間によっては固結と呼ばれる硬化現象を引き起こすため, 製造時に固結防止剤を添加している。今回, コンクリートへの影響が少なく, 貯蔵期間の延長を可能にした新規の固結防止剤を開発し, 固結抑制能力とコンクリートへ及ぼす影響について評価試験を実施した。