Blast Furnace Slag Replacement Research Articles

3성분계 무시멘트 경화체의 양생방법에 따른 강도특성

본 연구는 <TEX>$CO_2$</TEX>발생으로 인한 지구 온난화에 따른 해결책으로 고로슬래그, 레드머드, 실리카 흄 등을 시멘트를 대체하기 위한 기초적인 연구를 수행한 것으로 고로슬래그, 레드머드, 실리카 흄 및 알칼리 자극제를 사용하여 시멘트와 같은 성질을 가지는 경화체의 제조가 가능한지에 대한 실험적 검토를 실시하였다. 이를 위하여 시멘트 대체재로 고로슬래그, 레드머드, 실리카 흄 등의 무기결합재와 수산화나트륨(NaOH), 규산나트륨(<TEX>$Na_2SiO_3$</TEX>)등을 사용하여 비빔시간 변화에 따른 강도특성을 선행실험에 실시하였다. 선행실험을 바탕으로 본 실험에서는 기건양생, 수중양생, 피막양생, 한지양생을 실시함으로써 경화체의 강도특성에 대하여 분석을 실시하였다. 그 결과, 수중양생 <TEX>$80^{\circ}C$</TEX>의 경우 재령 28일에서 압축강도 및 휨강도가 가장 우수하였으며 무시멘트 경화체의 제조가 가능해서 친환경적인 콘크리트 생산에 커다란 영향을 미칠 수 있을 것으로 판단된다. This study was conducted as the basic research for the replacement of Blast Furnace Slag, Red Mud, Silica Fume, etc., with cement as a solution to the problems arising from the global warming caused by the generation of <TEX>$CO_2$</TEX>, and conducted the experimental review to examine the feasibility of matrix having properties identical to those of cement by using the Blast Furnace slag, Red mud, Silica fume, and alkali-activator. For this, by using the the inorganic binder, such as Blast Furnace Slag, Red Mud, Silica Fume, etc., and NaOH, <TEX>$Na_2SiO_3$</TEX> and others as the cement substitute material, the strength characteristic according to the mixture time variation was performed in the tentative experiment. Based on the preceding experiment, this study performed the experiment to analyze the strength properties of hardener through the curing by air-dry temperature, curing by temperature in water, coating curing, and Korean paper curing. For the water curing at <TEX>$80^{\circ}C$</TEX>, the compressive strength and flexural strength were found to be the most excellent at the age of the 28th day, and furthermore, it was found that the non-cement hardener could be made, which is considered to affect the production of eco-friendly concrete.

Efficiency of ground granulated blast-furnace slag replacement in ceramic waste aggregate mortar

From our previous findings, the recycling of ceramic waste aggregate (CWA) in mortar has been proved an ecological means plus an excellent outcome against chloride ingress. The CWAs were porcelain insulator wastes supplied from an electric power company, which were crushed and ground to fine aggregate sizes. In this study, to further develop the CWA mortar as an eco-efficient construction material, ground granulated blast-furnace slag (GGBS) was incorporated. The slag (having the Blaine fineness of 6230cm2/g) was utilized as a supplementary cementitious material (SCM) at three different replacement levels of 15%, 30%, and 45% of cement by weight. The efficiency of the GGBS on enhancing chloride resistance in the CWA mortars was experimentally assessed by using a silver nitrate solution spray method and an electron probe microanalysis (EPMA). The tests were carried out on mortar samples after immersed in a 5.0% NaCl solution for 24weeks. Another set of the mortar samples was exposed to a laboratory ambient condition for 24weeks and then followed with a carbonation test. The test results indicated that the resistance to the chloride ingress of the CWA mortar becomes more effective in proportion to the replacement level of the GGBS. In contrast, the carbonation depth of the CWA mortar increases with the increase of the GGBS. The activeness of the GGBS was also evaluated on the basis of the compressive strength development up to 91days. Due to its high fineness, the GGBS can be used up to 30% while the high relative strength (more than 1.0) is achieved at all ages.

Significance of Blast Furnace Slag as Coarse Aggregate in Self-Compacting Concrete

Self-compacting concrete (SCC) is a flowing concrete mixture that is able to consolidate under its own weight. The highly workable nature of SCC makes it suitable for placing in complex structural elements and in sections with congested reinforcement. Utilization of industrial waste products in the construction industry draws serious attention of many researchers and investigators. In this study an experimental investigation has been carried out to study the significance of blast furnace slag as partial replacement for coarse aggregate in fly ash blended self-compacting concrete. The coarse aggregate was replaced by blast furnace slag at 10% to 100% and various tests were conducted to determine the optimum level of replacement of blast furnace slag in self-compacting concrete. The specimens were subjected to compressive strength, split tensile strength and flexural strength tests in addition to fresh concrete properties. Slump flow, J-ring test, L-box, U-box and V-funnel tests were carried out for evaluating fluidity, filling ability and segregation properties of the fresh concrete. Based on the overall observations it could be concluded that an increase in slag proportion increases the strength properties and among the various percentages of replacement 30% is found to be optimum for maximum strength properties.

Influence of Blast Furnace Slag on the Mechanical Properties of High Performance Concrete

The characteristics of the compressive strength and splitting tensile strength according to replacement ratio of the blast furnace slag were found in this study. The blast furnace slag was utilizes as the concrete mix-material and then, these results were compared with the basis presented in the international standards. In this study, cylinder made of concrete with water/binder ratio 0.34 and blast furnace slag replacement rate of 10%, 30%, 50%, and 70% were prepared to measure the compressive strength and spiting tensile strength. Test results indicate that The 28 days and 91 days compressive strength is affected by blast furnace slag replacement except specimen BS30 and the splitting tensile strength in specimen BS series is slightly larger than that of OPC except specimen BS 30.

Effects of mineral admixtures and superplasticizers on micro hardness of aggregate-paste interface in cement concrete

This paper presents quantitatively the results of an experimental investigation on influence of mineral admixtures and superplasticizers on Vickers micro hardness (HV) of aggregate-paste interface in cement concrete. The HV was measured by Vickers hardness testing equipment. The results indicate that addition of fly ash decreases HV of the concrete. Although it decreases with the increase of ground granulated blast furnace slag (GGBS) replacement, the HV is higher than that of concrete containing fly ash at all replacements. The flying ash and GGBS composition increases HV in later curing ages, but does not improve it in early curing ages. Aminosulfonic acid based superplasticizer and aliphatic hydroxy sulphonate condensate superplasticizer can enhance HV in early curing ages. The HV of concrete with polycarboxylic acid superplasticizer is higher in later curing ages.

반응표면설계법(反應表面設計法)을 이용한 고로(高爐)슬래그 경량기포(輕量氣泡)콘크리트 제조(製造)의 최적화(最適化)

고로슬래그(BFS) 경량기포콘크리트 제조의 최적 배합비를 도출하기 위해 반응표면분석법 중 하나인 Box-Behnken법을 이용하여 연구를 수행하였다. 경량기포콘크리트는 상압증기양생법으로 제조하였으며 주요 실험변수로는 물/분체(<TEX>$W/P_d$</TEX>)비, BFS 치환률 그리고 분체량(<TEX>$P_d$</TEX>) 기준 Al분말 첨가량을 설정하였다. 반응표면분석에 의해 경량기포콘크리트의 절건비중 및 압축강도에 대한 회귀 모델식이 유도되었다. 경량기포콘크리트의 절건비중과 압축강도에 대한 목표값을 각각 0.72와 4.42 MPa로 설정하고 회귀 모델식에 의해 도출된 경량기포콘크리트의 최적 배합비는 <TEX>$W/P_d$</TEX>비 0.62, BFS 치환률 35.5% 그리고 분체대비 Al분말 첨가량 0.05%이었다. 이처럼 도출된 배합비로 제조한 경량기포콘크리트 시험체에 대한 절건비중과 압축강도의 측정값을 통해 회귀 모델식의 신뢰성이 확인되었다. This study was conducted to optimize a mixing design of lightweight aerated concrete with the blast furnace slag(BFS) using Box-Behnken method, one of response surface designs. The lightweight aerated concrete with the BFS was made on the conditions of steam curing method at atmospheric pressure. The experimental factors were unit Water(W)/total powder(<TEX>$P_d$</TEX>) ratio, BFS replacement percentage and Al powder addition based on the total powder (<TEX>${P_d}^*$</TEX>%). From the results of the response surface analysis, regression models for dried specific gravity and compressive strength of the lightweight aerated concrete were derived. When the target values for dried specific gravity and compressive strength of the lightweight aerated concrete were set at 0.72 and 4.42 MPa respectively, its optimized mixing conditions driven from the regression models were 0.62 of <TEX>$W/P_d$</TEX> ratio, 35.5% of BFS replacement and 0.05% of Al powder addition. This experimental design model was found to be credible by measuring the dried specific gravity and compressive strength of the sample made from the above mixing conditions.

EFFECTS OF BLAST FURNACE SLAG ON CHLORIDE PERMEABILITY OF CONCRETE

Chloride-induced corrosion of steel reinforcement is the main cause of deterioration of reinforced concrete structures in marine environments. The penetration of chlodride ions into concrete cover that accelerates corrosion process of steel reinforcement, this affects the bearing capacity of structures. This paper investigates on chloride permeability cheracteristic of concrete using blast furnace slag in terms of chloride diffusion coefficient and chloride binding capacity. The concrete used in this research has grade of 45MPa and the slag content replacement of cement PC50 is in range of 0% - 70%. The chloride diffusion coefficient of concrete is determined by ASTM C1202 and NordTest NT Build 492. Results showed that the blast furnace slag replacement increases (from 0% to 50%), the chloride ion diffusion coeffient decreases and bound chloride content in concrete increases. It is clear to conclude that blast furnace slag can be used to replace cement PC50 in range of 30% to 40% in order to increase the resistance of concrete to chloride penetration without affecting concrete strength.

The influence of the blast furnace slag replacement on chloride penetration in concrete

Corrosion of steel reinforcement due to chloride penetration is the greatest cause of durability problems in concrete; intense international research has been carried out to understand and avoid this. This paper summarises the results of a theoretical and experimental research programme investigating the influence of blast furnace slag on chloride-related transport properties. The relationship between the apparent chloride diffusion coefficient, electrical resistivity and compressive strength was measured. Chloride, hydroxide, sodium and potassium's intrinsic diffusion coefficients were obtained by using a computational model and an electrical migration test. The initial hydroxide composition of the pore solution, porosity and chloride binding capacity were also determined from the model. The results showed that blast furnace slag improved chloride penetration resistance, resulting in concrete which was less vulnerable to corrosion.

Efficiency of granulated blast furnace slag replacement of cement according to the equivalent binder concept

Abstract The strength development of slag cement has a great consideration for the scheduling of formwork removal, prestressing operations, and other practical aspects of slag cement usage. The prediction of slag concrete strength, using the Feret’s model has been studied by introducing the concept of the equivalent binder. This has led to define an efficiency coefficient of slag which distinguishes the latter with the regard to the cement. Thus, this obtained coefficient characterizes well the slag and lets to predict the slag concrete strength from strength values of a normal concrete made without slag for a given age and replacement rate. At 90 days age, the test results show that for 15% replacement rate, the slag is activated completely and gives 67% of efficiency more than the cement. For higher replacement rate, the efficiency of the slag decreases and becomes similar to that of cement for 50% replacement rate.

Genetic expression programming for prediction of heat of hydration of the blended cements

This study presents a new approach based on Genetic Expression Programming (GEP) for modeling of variation of heat of hydration of Portland and blended cements. For that purpose, two different GEP models were developed to generate two mathematical equations. In the GEP Model 1, six input parameters such as the ground blast furnace slag replacement ratio (GBFS), ground basaltic pumice replacement ratio (GBP), clinker and gypsum ratio (CG), cement fineness (CF), grinding type (GT) and time (T) were used. In GEP Model 2, three input parameters such as cement fineness (CF), grinding type (GT) and time (T) were used. The results were highly promising in terms of training performances and prediction accuracies and revealed that the proposed GEP models can be used in the prediction of heat of hydration of blended cements. Key words: Cement, heat of hydration, genetic expression programming.

Influence of Interstitial Phase Composition and Granulated Blast-Furnace Slag on the Adiabatic Temperature Rise of Cement

When the utilization volume of industrial wastes and by-products in cement plants are increased, it is necessary to control the adiabatic temperature rise of cement containing a large amount of the interstitial phase. As previously reported, we produced an adiabatic calorimeter in order to evaluate the adiabatic temperature rise using about 30mL of mortar sample only. In this study, we investigated the influence of interstitial phase composition and ground granulated blast-furnace slag on the adiabatic temperature rise of the cement mortar using the advanced calorimeter. Changes in adiabatic temperature rise were negligible even when the amount of interstitial phase of cement was increased from 18mass% to 21mass%. It was confirmed that the adiabatic temperature rise of cement containing the interstitial phase of more than 21mass% was improved by a 20mass% replacement of blast-furnace slag.

Thermal conductivity and compressive strength of concrete incorporation with mineral admixtures

In this study, the effect of silica fume (SF), class C fly ash (FA), blast furnace slag (BFS), SF+FA, SF+BFS, and FA+BFS on the thermal conductivity (TC) and compressive strength of concrete were investigated. Density decreased with the replacement of mineral admixtures at all levels of replacements. The maximum TC of 1.233W/mK was observed with the samples containing plain cement. It decreased with the increase of SF, FA, BFS, SF+FA, SF+BFS, and FA+BFS. The maximum reduction was, 23%, observed at 30% FA. Compressive strength decreased with 3-day curing period for all mineral admixtures and at all levels of replacements. However, with increasing of curing period reductions decreased and for 7.5% SF, 15% SF, 15% BFS, 7.5% SF+7.5% FA, 7.5% SF+7.5% BFS replacement levels compressive strength increased at 28days, 7- and 28-days, 120days, 28- and 120days, 28days curing periods, respectively. Maximum compressive strength was observed at 15% BFS replacement at curing period of 120days.

Optimal Mixture Proportion for High Performance Concrete Incorporating Ground Granulated Blast furnace Slag

In this study, a mix design for self compacting concrete was based on Okamura's method and concrete incorporated just a ground granulated blast furnace slag. Replacement ratio of slag is in the range of <TEX>$20-80\%$</TEX> of cement matrix by volume. For the optimal self compactability in mixture incorporating ground granulated blast furnace slag, the paste and mortar tests were first completed. Then the slump flow, elapsed time of 500mm slump flow, V funnel time and filling height by U type box were conducted in concrete. The volume of coarse aggregate in self compacting concrete was in the range of <TEX>$50-60\%$</TEX> to the solid volume percentage of coarse aggregate. Finally, the compressive and splitting tensile strengths were determined in the hardened self compacting concrete incorporating ground granulated blast furnace slag. From the test results, it is desirable for self compacting concrete that the replacement of ground granulated blast furnace slag is in the range of <TEX>$40-60\%$</TEX> of cement matrix by volume and the volume of coarse aggregate to the solid volume percentage of coarse aggregate with a limit of <TEX>$55\%$</TEX>.

고로슬래그를 함유한 콘크리트의 자기수축 특성

초록 · 키워드 목차 오류제보하기 등록된 정보가 없습니다. ABSTRACT1. 서론2. 실험 연구3. 실험결과 및 분석4. 자기수축 예측 모델5. 결론참고문헌요약

Influence of mineral admixtures on thermal conductivity and compressive strength of mortar

Cement paste with natural sand content and the effect of silica fume (SF), class C fly ash (FA) and blast furnace slag (BFS) on the thermal conductivity and compressive strength of mortar was investigated. SF, FA and BFS were added as replacement for cement by decreasing the cement in the ratios of 10, 20 and 30% by weight. The maximum thermal conductivity of 1.186 W/mK was observed with the samples containing plain cement. It decreased with the increase of SF, FA and BFS as replacement for cement. The reductions due to SF were 17, 31 and 40% for 10, 20 and 30% SF (replacement for cement), respectively. FA induced reductions of 14, 26 and 33% for 10, 20 and 30% FA, respectively. Both SF and FA had a decreasing effect on thermal conductivity. BFS effect on the thermal conductivity, was approximately the same at all percent (BFS replacement for Portland cement, PC) and the reduction values were between 12 and 14%. Ten percent SF and 10 and 20% FA and all level BFS increased compressive strength a little at 120 days. However, except 10% SF the other admixters at all level replacement decreased compressive strength at early ages, especially FA decreased compressive strength as function of replacement percent.