Earticle

The study is propertys analyze such as the paste rheology, yield value and compressive strength etc. with used to the admixture micro powder manufacture high flow mortar, the purpose was the it`s obtain design of mix proportion of the high flow concrete or mix design necessary basic date. The result is admixture balance rate was highed according to the transposition rate to be good working a ball bearing flexibility. However, W/B is raised that it judge the unit volume weigh more than rising the flexibility is the huge affect according to the admixture`s transposition rate or addition rate of high range water reducing admixture. A special quality of mortar was according to the admixture transposition rate drop the early-age strength and it raising strength with keep dropping the W/B. It was reveal that as result of plzzoanic reaction of admixture is low early-age strength and high long-time strength. The conclude, in the more than variety of the mix condition that the research need about the high-fiuidity concrete of theory design of mix proportion or mix design method.

This study was conducted to investigate some effects of Cemesol on acidresistance and compressive strength of concrete. In mix design of concrete, the cemesol was used as an admixture of cement, and it was added to the mix in an amount equal to 0.1%, 0.2%, 0.3%, and 0.4% by weight of cement of the mix. Concrete specimens were made in accordance with the. Korean Standard Specification for concrete and they were tested for acid-resistance and compressive strength at 2 weeks intervals through 8 weeks. The tests were performed in two cases non-curing and curing for 28 days. The results obtained from the tests are summarized as follows. 1. Refering to acid-resistance test, the cemesol was comparatively effective at every cemesol content except 0.3% in case of non-curing and it was found that cemesol content of 0.4% was the optimum. On the other hand, the cemesol was ineffective in case of curing, but it was seen that cemesol content of 0.1% had some effect at 6 to 8 weeks curing only. 2. Refering to compressive strength test, the cemesol was remarkably effective at a content of 0.1% but it was also shown most inefiective at content of 0.3% in case of non-curing. On the other hand the cemesol was comparatively effective at every content of cemesol except a content of 0.2% in case of curing and it was determined that the cemesol content of 0.3% may be an optimum content. 3. Since optimum cemesol content varied according to acid-resistance, compressive strength and cases such as non-curing and curing, as indicated above may be desirable to choose an optimum cemesol content suitable for purposes and ciroumstances of construction works or conditions of location. 4. The corrosive rate was proportional to compressive strength in case of non-curing, but the relation was reversed in case of curing. It was found that corrosive rate for 8 weeks did not influence compressive strength in case of non-curing but compressive strength in case of curing begins to vary under the influence of corrosion. Thus, corrosion may be more serious to compressive strength in case of curing than that in case of non-curing.

국산 플라이애쉬 6종류에 대한 AE제의 흡착특성(吸着特性)을 살펴 본 결과 플라이애쉬 입자의 AE제흡착(吸着)은 30분 정도에서 거의 완료되었으며 강열감량이 클수록 포화흡착량이 크게 나타났다. 플라이애쉬 강열감량의 대부분은 미연소탄소(未燃燒炭素)이며 따라서 미연소탄소량이 AE콘크리트 중의 공기량을 감소시키는 요인임을 알았다. 한편, 유동화제(流動化劑)의 경우 플라이애쉬 입자의 포화흡착량은 시멘트보다 적으며 시멘트의 경우보다 분산성(分散性)도 다소 낮으나 플라이애쉬를 혼합한 콘크리트에 유동화제를 사용할 경우 유동성이 저하되는 현상은 없었다.

From the test results of the adsorption characteristics of AE admixture, it was shown that the adsorption of AE admixture on fly ash was mearly completed in 30 minutes and the higher was ignition loss, the larger the quantity of saturation adsorption. Because most of the ignition loss of the fly ash was due to the unburned carbon, it could be said that the unburned carbon is the main reason of reduction of air content in AE concrete. On the other hand, in the case of superplasticizer, the amount of saturation adsorption in fly ash was lower than in cement and the same result was obtained in the dispersive effect. But, when using superplasticizer in fly ash substituting concrete, the fludity in the concrete was not decreased.

본 연구에서는 하중조건과 혼화재료의 영향을 고려하여 콜드조인트를 가진 콘크리트의 투수성을 정량적으로 실험적으로 평가하였다. 물-결합재비 0.6과 40%의 고로슬래그 미분말 치환률을 가지는 콘크리트 시편에 콜드조인트 콘크리트를 유도하였으며, 압축영역에서는 최대응력의 0%, 30%, 60%, 인장영역에서는 최대응력의 60%로 하중수준을 고려하여 투수성을 평가하였다. OPC 콘크리트 투수계수는 Control에서 $2.41{\times}10^{-11}m/s$로 평가되었는데, 압축하중 30% 조건에서 $2.07{\times}10^{-11}m/s$로 감소하였으나 60% 조건에서는 $2.36{\times}10^{-11}m/s$로 증가하였다. 또한 GGBFS 콘크리트의 투수계수는 각각 $2.17{\times}10^{-11}m/s$, $1.65{\times}10^{-11}m/s$, $1.96{\times}10^{-11}m/s$로 같은 경향을 나타내었다. 인장영역에서는 OPC 배합의 투수계수는 Control에서 $2.37{\times}10^{-11}m/s$ 였으나 60% 조건에서 $2.67{\times}10^{-11}m/s$ 로 증가하였다. 또한 GGBFS 콘크리트에서는 각각 $2.17{\times}10^{-11}m/s$, $2.24{\times}10^{-11}m/s$로 평가되었다. 압축응력 조건에서 투수성은 하중의 증가에 따라 초기에 감소하다가 증가하였으며, 인장응력 재하시에서는 빠른 증가를 나타내었다. 이는 콘크리트내의 공극구조가 하중의 증가에 따라 압밀되고 이후 미세균열발생으로 인해 투수성이 증가하게 된다. 일반 콘크리트에 비해 고로슬래그 미분말, 하중조건, 콜드조인트는 투수성을 크게 변동시키므로 이를 고려한 투수성 평가가 필요한 것으로 확인되었다.

This paper presents a quantitative evaluation of water permeability in concrete with cold joint considering mineral admixture and loading conditions. Concrete samples with OPC (Ordinary Portland Cement) and GGBFS(Ground Granulated Blast Furnace Slag) are prepared considering 0.6 of W/C ratio and 40% of replacement. 30% and 60% loading levels for compression and 60% loading level for tension are induced to concrete samples. In compression conditions, the permeability in control case shows $2.41{\times}10^{-11}m/s$ in OPC concrete, and it changes to $2.07{\times}10^{-11}m/s$ (30% of peak) and $2.36{\times}10^{-11}m/s$ (60% of peak). The results in GGBFS concrete shows the same trend, which yields $2.17{\times}10^{-11}m/s$ (control), $1.65{\times}10^{-11}m/s$ (30% of peak), and $1.96{\times}10^{-11}m/s$ (60% of peak), respectively. In tensile conditions, the permeability increases from $2.37{\times}10^{-11}m/s$ (control) to $2.67{\times}10^{-11}m/s$ (60% of peak) while that in GGBFS concrete increases from $2.17{\times}10^{-11}m/s$ (control) to $2.24{\times}10^{-11}m/s$ (60% of peak). Permeability coefficients decreases in 30% of compressive level but increases in 60% level, while results in tensile level increases rapidly. This shows pore structure in concrete is condensed and with loading and permeability increases due to micro-cracking. Permeability evaluation considering the effects of loading conditions, cold joint, and GGBFS is verified to be important since water permeability greatly changes due to their effects.

한중(寒中)콘크리트 시공(施工)에 염화(鹽化)칼슘사용(使用)은 콘크리트의 초기강도(初期强度)를 최대한(最大限)으로 높여 동해(凍害)를 방지(防止)함과 경제적(經濟的인 구조물(構造物)을 만들고자 하는데 목적(目的)이 있으며 시험결과(試驗結果)로서 그의 범위(範圍)를 요약(要約)하면 다음과 같다. 1. 염화(鹽化)칼슘을 시멘트중량비(重量比) 1.5%를 TYPE I TYPE II에 혼합(混合)하면 초기강도(初期强度)를 최대한(最大限)으로 증진(增進)할 수 있고 구조물(構造物)의 안전(安全)을 위(爲)해서 1.5%내외(內外)가 적합(適合)하겠다. 2. 염화(鹽化)칼슘을 혼합(混合)하여 동결(凍結)의 위험(危險)을 방지(防止)하기 위한 콘크리트를 만들자면 w/c비(比)를 50% 내외(內外)로 정(定)해야 만이 한중(寒中)에 안전(安全)하겠다. 3. 포조란 초기강도(初期强度)는 떨어지나 후기강도(後期强度)가 점차(漸次)로 상승(上昇)한다. 4. 콘크리트의 초기강도(初期强度)의 증진(增進)으로 양생기간(養生期間)을 최대한(最大限)으로 단축(短縮)시킬 수 있으므로 콘크리트 구조물(構造物)의 끝손질을 조기(早期)에 실시(實施)해야 한다. 염화(鹽化)칼슘의 혼입(混入)은 시멘트응결(凝結)을 촉진(促進)시킬 수 있어 한중(寒中)에 있어서 동해(凍害)를 방지(防止)하고 공기(工期)를 최대한(最大限)으로 단축(短縮)시킬 목적(目的)으로 공사시공(工事施工) 현장(現場)에서는 유효히 사용(使用)될것으로 사료(思料)된다.

In many cold weather concrete constructison jobs calcium chloride $CaCl_2$ can be used safely as an accelerating admixture. For producing satisfactory concrete during cold weather calcium chloride is used to develop the level of strength required in a shorter period by obtaining higher early strength, the resulting in crease in heat of hydration. In this paper, to get adequated data and information of the effect on strength of concrete in using calcium chloride as an accelerating admixture, Portland cement (Type I), High-early-strength cement(Type II) and Pozzolans cement with certain 1.5 percentage of calcium chloride by weight of the cement were tested. As the result of this experiment, followings were founded: 1. At the 1.5 percent of calcium chloride cement ratio, the early strength was accelerated to the highest level, and some 1.5 percent of calcium chloride cement ratio was suitable for the stabilization of the concrete structures. 2. For Some 50 percent of Water Cement ratio was suitable, making good Concrete in the Cold weather by admixture of Calicum Chloide. 3. The concrete of Pozzorans cement in early strength was weak but that in later rised by degree. 4. As abtaining higher early strength the curing period can be reduced, but the finishing work should be done as early as possible.

제지산업은 다량의 산업부산물을 배출하고 있으며, 제지애쉬 발생량도 증가하고 있다. 본 연구에서는 제지애쉬를 시멘트 혼합재로 사용하기 위해서 수화수를 사용하여 전처리 하였다. 전처리 제지애쉬와 석고를 혼합하여 혼합재를 제조하였으며, 이후 시멘트를대체하여 사용하였다. 제지애쉬 혼합시멘트는 제지애쉬 함량에 따라 물성이 변화하였으나, 10% 이하 사용시에는 기존 OPC와 동등물성이 발현되었다. 이때 압축강도는 수화물 중 Ca(OH)2의생성량과도 일정 상관성을 나타내었으며, 3일 강도는 Ca(OH)2 함량이증가할수록, 28일 강도는 감소할수록 압축강도가 증가하였다.

Abstract Paper industry discharges many by-products and quantity of PSA (Paper sludge ash) has been increased. In this study, hydration water was added to PSA for use as cement admixture. PSA with added water was mixed with anhydrite and this mixture was used as cement substitute. Physical properties of PSA cement were changed by contents of PSA, but PSA cement containing PSA less than 10% had similar properties to those of OPC. Compressive strength of PSA cement mortar had a certain relationship with Ca(OH)2 content. Compressive strength at 3 days increased, as Ca(OH)2 content increased. However, the strength at 28 days increased, as Ca(OH)2 content decreased.

건설 분야 중 건설 재료와 건자재 산업에서 발생하는 CO2는 약 6,700만톤으로 건설 분야에서 발생하는 CO2의 약 30%를 점유하고 있다. 건설 분야에서 CO2 저감은 건자재 산업에서 CO2를 발생시키는 2차, 3차 양생을 줄여 소비되는 화석연료 사용과 배출가스 저감의 조절이 필수적이다. 따라서 본 연구는 저에너지양생용 혼합재(Low energy curing Admixture 이하 LA)를 압출성형패널에 적용한 후 그 혼입량, 섬유종류, 섬유 혼입율에 따른 물리적 특성을 관찰하였다. 섬유종류가 강도에 영향을 나타내는 주요한 인자는 아닌 것으로 나타났으며, LA 혼입율과 섬유 혼입량은 강도에 영향을 주는 주요한 인자인 것으로 나타났다. 특히 LA 혼입율dl 40% 일 때 가장 높은 강도발현을 나타냈으며, 50% 인 시험체의 경우 강도가 하락하는

CO2 emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30 % of CO2 emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of CO2 in the construction area as we reduce the second and third curing to emit CO2 in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter “LA”) to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.

본 연구는 국내 제철소에서 산업부산물로 발생되는 고로슬래그 미분말을 콘크리트용 혼화재료로 사용 가능한지를 알아보기 위한 연구의 일환으로 고로슬래그 미분말 자체의 화학성분, 물리적 성질 등과 같은 품질에 대하여 분석 검토하였다. 아울러 고로슬래그 미분말을 몇 단계로 혼합한 모르터 및 콘크리트의 콘시스텐시와 각 재령별 압축강도 및 내약품성에 대하여 기초적인 실험을 실시해 본 결과 장기재령에서 압축강도가 증가되었으며, 약품에 대한 모르터의 저항성도 우수함을 알 수 있었다.

The objective of this research is to analyze whether the ground granulated blast furnace (GGBF) slag, by-product of industry in domestic iron-foundary, can be useful as a mineral admixture for concrete by investigating physical and chemical property. In addition, according to making an fundamental experiment on mortar and concrete mixed with GGBF slag to some grade, examining the consistency, the compressive strength and the resistance to sulfate attack of concrete and mortar, the acquired results are that the compressive strength was increased and the resistance to sulfate attack was predominant.

고성능감수제를 사용한 콘크리트의 유동성 손실을 저감시키기 위한 연구의 일환으로 시멘트의 종류, 고성능감수제의 종류, 사용방법 및 사용량이 굳지않은 콘크리트의 유동성 손실에 미치는 영향을 파악하기 위하여 시멘트풀, 모르터 및 콘크리트의 유동성 손실과 관련된 실험을 통하여 얻어진 결과에 대하여 고찰하였다. 본 연구결과 고성능감수제의 첨가시기는 시멘트 및 고성능감수제의 종류에 따라 다소 차이가 있으나 30분후 첨가방법이 유동성 손실을 줄이는데 유효하였으며, 대체로 고성능감수제 사용량이 많을수록 유동성 손실이 크게 나타났으며 보통포틀랜드시멘트 콘크리트가 유동성 손실이 가장 크고 플라이애쉬 20% 혼합시멘트 콘크리트에 나프탈린계 고성능감수제를 30분후 첨가한 경우 유동성 손실이 매우 작은 효과가 있었다.

This study gives results of 1aboratory investigations to minimize the slump loss of concrete using high range water reducing admixture (HRWR). Various factors influencing on the slump loss such as cement type, HRWR type and dosage time are investigated. The acquired results indicated that 30 minutes delayed dosage of HRWR is very effective on reducing the slump loss though this tendency makes a difference to some extent according to cement and HRWR type. For the most part, the more usage of HRWR increases, the higher the slump loss occurs and concrete using ordinary portland cement has the highest slump loss and concrete using fly ash 20% replacement cement with HRWR of naphthalene type has the good effect on reducing the slump loss.

According to the test, An increase of super-retarding-agent (SRA), which combined the SRA with admixture, delayed initial and final setting time. Interestingly control concrete incorporating only admixture also retarded setting time. In addition concrete, adding combination of the SRA and admixture simultaneously, exhibited considerable results, due to the absorbing, pozzolanic and potential hydraulicity reaction of the admixture. Overall, to secure initial setting time as control concrete does, particular coefficient value considering the properties of each materials, should be applied, before it is placed in the field construction.

The purpose of this study is to investigate the effect of different levels of cement replacement(0, 5, 10, 15, 20, 25%) by copper slag as admixture on the expansion of mortar bars containing reactive aggregates. The experimental program included expansion measurement of the mortar bar specimens, also the determination of the morphology and composition of the alkali-silica reaction products by using scanning electron microscopy(SEM), energy dispersive x-ray(EDX), and x-ray fluorescence spectrometer(XRF). The results indicate that more than 15% percent replacement of portland cement by copper slag stop deleterious expansion due to the alkali-silica reaction. Also it was found that the expansion rate increased with the increase of the CaO/SiO2 and CaO/(Na2O)e ratio from the comparison of the oxide compositions with the different levels of replacement by copper slag.

This paper reports the study on the shrinkage property of expansive strain-hardening cement-based composite (SHCC) materials containing 1.5% polyethylene (PE) fibers volume fraction. Variables were cement types (ordinary portland cement, OPC and ultra-high early strength cement, UESC) and 2 replacement levels (0, 10%) of an expansive admixture (EXA). A number of experimental tests were conducted to investigate shrinkage and compressive strength. The test results indicated that using UESC improves compressive strength of SHCC. Also, replacement of EXA on SHCC can reduce the huge shrinkage value and EXA has fewer effects on UESC specimens than OPC specimens.

혼화재료로 사용한 규조토 분말이 모르타르의 강도에 미치는 영향을 검토하기 위하여 시판되고 있는 건조상태의 비소성제품과 소성제품 각 1종류 및 융제소성제품 2종류 등 모두 4종류의 규조토 분말을 사용한 모르타르의 물성실험을 실시하였다. 규조토 분말을 시멘트 질량으로 10% 범위 내에서 대체 사용하고 물-결합재비를 동일하게 한 모르타르 실험결과로서, 소성제품을 사용한 경우는 그 사용량의 증가에 따라 재령 7일, 28일 및 56일의 전체 시험재령에서 압축강도 및 휨강도가 증가하는 경향을 나타냈다. 그러나 비소성제품은 모르타르의 유동성을 저하시켜 단위수량을 크게 증가시키는 문제점이 있었으며, 융제소성제품은 모르타르의 강도개선효과가 나타나지 않았다.

When diatomite powder was used as an admixture in mortar, its effects on the mortar strength was examined by experimental tests. For the tests, 4 kinds of commercially available diatomite powder were purchased ; one non-calcined product, one calcined product, and flux-calcined product two. The compressive and flexural strength of the mortar according to the increase of added amount of calcined diatomite powder increased at all test ages(7, 28, and 56 days). However, the use of non-calcined diatomite powder worsened the fluidity of mortar severely and that caused much more required water content. And flux-calcined product did not show useful effect on the mortar strength.

Recently, the industrial waste is scattered and one of the oyster also make the serious environmental contamination. So, the purpose of this study is investigating an utilization ability as calcium binder of the oyster which is an industrial by-product. According to the previous experimentation calcining condition strength of 1000℃(120min) is higher than any other conditions. So this study shows an effect that the oyster mixes with admixtures such as fly ash or blast furnace slag by rates (10%, 20%, 30%, 40%, 50%). The compressive strength and flow of the paste in mixing condition increase. Especially, when the oyster alternates the 50% of rate with blast furnace slag the setting time has more useful condition.

In this paper, the results of setting and strength properties of concrete incorporating cement kiln dust, fly ash and blast furnace slag respectively are reported in order to reduce hydration heat of mass concrete and achieve economical advantage. According to test results, setting time was not affected by CKD contents, whereas The use of FA with 10% and 20% retarded the setting time more than 2 hours. The increase of BS with 20 and 40% delayed setting time more than 1.5 hours. For compressive strength, the increase of CKD reduced the compressive strength. The use of CKD with 10% had little effect on strength gain. The use of FA and BS resulted in a reduction in compressive strength in proportion to the contents at early age. At 28days, compressive strength with FA and BS exhibited a parabola curve with an increase in FA and BS contents. Higher strength gain was achieved in 10% of FA and 20% of BS at 28days. It can be seen that the use of mineral admixture in mass concreting considering placing layer can reduce hydration heat and economical advantage

Grout is used for filling joint of concrete structures, and it is required to have fluidity, required strength and shrinkage reduction performance. However, in cement-based grout, drying shrinkage is inevitable due to evaporation of surplus water during hydration reaction. Therefore, in this study, the physical properties of cement-based grout according to the replacement ratio of CSA expansion admixture were analyzed to reduce drying shrinkage. As an experimental results, fluidity increased as the replacement ratio of the expansion admixture increased, and the setting time accelerated as the replacement ratio of the expansion admixture increased. In terms of compressive strength, the initial compressive strength increased by about 7 % when the replacement ratio of the expansion admixture was 3 to 6 %, other than that, the compressive strength decreased as the replacement ratio of the expansion additve increased, so the target strength was not satisfied with the replacement ratio of the expansion admixture of 15 %. The expansion height was contracted(-) up to 6%, and the replacement ratio of 9% or more was expanded(+). The length change in drying shrinkage decreased as the replacement ratio of the expansion admixture increased, and increased as the curing temperature increased. However, compared with the replacement ratio of 0 %(Plain), the higher curing temperature, the better the compensation effect for shrinkage. As a result, it was found that the use of 9 to 12% of the expansion admixture was appropriate within the scope of this study.