Electrical waste, such as heavy weight waste glass, has become a global concern in terms of resource recycling. At the same time, aggregate is one of the most widely used infrastructure materials, and it is being exhausted. So, in this paper, the heavy weight waste glass is considered as aggregate due to its physical characteristics and chemical composition. From the results, when the heavy weight waste glass substitution ratio increase, the compressive strength and flexural strength decreased.

This paper describes the flexural characteristic of high strength steel fiber reinforced concrete (SFRC) prisms with different fiber tensile strength. All mixtures have specified compressive strength of 80 MPa and fiber volume fraction of 0.5% and 1.0%. In accordance with EN-14651, SFRC prisms were made and tested under bending loading. Test results indicated that steel fiber has no significant effects on compressive behavior of SFRC. However, flexural behavior of high strength SFRC was improved considerably with increase of fiber tensile strength.

The purpose of this study is determining the effects of flexural behavior of aramid fibers in ultra high performance concrete. The 10 kinds of aramid fibers with different length, diameter and twisting were used. The flexural behavior was determined by bending tests on specimens, which was prepared by mixing 1 % of volume fractions of aramid fibers into ultra high performance concrete mortar. Consequently, the load-displacement relationship curves were obtained by using the test results for each kinds of aramid. While the specimen that contains the small diameter of aramid fiber gives the strong flexural strength due to large contact area between the fiber and concrete matrix, that specimen by small diameter of aramid fiber does not guarantee the ductile behavior of specimen like the steel fiber. But the length and twisting of aramid fiber gives the ductile behavior of ultra high performance concrete flexural specimen.

본 연구에서는 유압식 급속재하 시험 장치를 제작하여 변형 속도에 따른 후크형 강섬유 및 폴리아미드 섬유보강 시멘트 복합체의 압축강도 및 인장강도 특성을 평가하였다. 그 결과, 변형 속도가 증가함에 따라 압축강도, 최대 응력 점에서의 변형 및 탄성계수는 증가하였으 며, 섬유 종류 및 혼입률은 변형 속도에 의한 압축강도의 영향은 크지 않았다. 본 연구에서 평가된 압축강도의 DIF는 CEB-FIP model code 2010 에 비해 상회하였으며, ACI-349의 예측값과 유사한 경향이 나타났다. 인장특성의 경우에도 변형 속도가 증가함에 따라 인장강도와 변형능력 이 크게 향상되었다. 후크형 강섬유보강 시멘트 복합체는 변형 속도가 증가함에 따라 섬유와 매트릭스의 부착력이 증가하는 것에 의해 인장강 도와 변형능력이 크게 향상되었으며, 섬유가 매트릭스로부터 인발되는 파괴 특성이 나타났다. 한편, 폴리아미드 섬유보강 시멘트 복합체의 경 우 섬유와 매트릭스의 부착력이 크기 때문에 섬유가 매트릭스로부터 인발되지 않고 끊어지는 파괴 특성이 나타났으며, 폴리아미드 섬유보강 시멘트 복합체의 인장특성에 대한 변형 속도 효과는 섬유의 인장강도에 큰 영향을 받는 것으로 판단되었다. 이러한 결과로부터 폴리아미드 섬 유보강 시멘트 복합체의 인장강도에 대한 변형 속도의 효과는 후크형 강섬유의 부착력에 대한 민감도 보다 큰 것으로 사료된다.

Powder mine wastes cause secondary environmental problems from dust flying around villages. It is necessary to recycle to prevent this secondary pollution and to use its beneficial contents. Magnesium and iron may play a role like that of aluminum in geopolymer forming. In this study, therefore, we analyzed the compressive strength of geopolymer prepared from melting slag (MS) and high-magnesium iron mine waste (MW). The compressive strength increased by increasing the mixing ratio of MS and decreasing the L/S ratio. The optimal properties were obtained at a mixing ratio of MS to MW of 5 : 5, molar ratio of SiO2/Na2O of 1.8, and L/S ratio of 0.2. Under these conditions, the compressive strength at 28 days was 112.5 MPa. According to the FT-IR analysis, a geopolymer structure was identified. As a result, we confirmed the possibility of geopolymer forming from MS and MW.

By analyzing the compressive strength througth field test execution on the shotcrete mixture with 40% blast furnace slag and slurry accelerator, confirmed the suitability as subsea tunnel material. As a result, strength characteristic on the anti-chloride shotcrete is excellent evaluated in terms of compressive strength compared with existing shotcrete.

This study examined the effect of outside temperature on the properties of high-strength concrete to determine conditions for four-season construction. With 20 ℃ as the reference temperature, 20, 30, and 40 ℃ were set as hot weather conditions, and 5, -10, and –20 ℃ as cold weather conditions. Properties as the effect of outside temperature on compressive strength of high-strength concrete was studied.

This paper investigates the strength properties of ground granulated blast furnace slag(GGBFS) with magnesium sulfate(MgSO4). GGBFS was replaced with 1, 2, 3, 4, and 5% MgSO4 by weight. Mixtures of sodium hydroxide(NaOH) and sodium silicate(Na2SiO3) were used as the alkaline activator; a mixture of 5% NaOH and 5% Na2SiO3, and a mixture of 10% NaOH and 10% Na2SiO3 by slag weight. The added activators were dissolved in the water, and the weight ratio of water to slag was 0.45. This study was performed using compressive strength testing, ultrasonic pulse velocity(UPV), water absorption and X-ray diffraction(XRD). In this study, the strength of hardened samples decreases with increasing MgSO4 content. In addition, the water absorption of samples increases and UPV decreases, with the increase of MgSO4 content. Brucite, gypsum and M-S-H(magnesium silicate hydrate) are present in the XRD patterns of the hardened samples.

In this study, Retarder, which shows characteristics of delay hydration reaction and reduce hydration heat in concrete, was processed through granulation and paraffin coat to induce reation by hydration heat. Concrete with Granulated and paraffin coated retarder were prepared and compressive strength was measured by curing at 20℃ and 40℃. As a result, it was confirmed that retarder exhibits performance depending on the curing temperature.

In this study, cement mortar (KS F 4042) used for repairing concrete structures was evaluated for compressive strength and bond strength according to the mixing ratio of polymer. From the experimental results, it was confirmed that as the polymer content increases, the bond strength properties increase, but the compressive strength decreases slightly at a certain rate.

In this research, in order to improvement the performance of the two-component mixed aggregate mixed with fine granite fine aggregate and seawater, the examination of the effect of reject ash on the cement mortar according to the change of substitution rate was done. As a result, it was found that the effect of improving the compressive strength is more effective when the rejection ash is replaced by 5% in the mixed aggregate than in the case of using the high quality aggregate.

This research proposed MPC (Magnesia Phosphate Composite) mortar as a rapid repair material. But because this rapid reactivity inherently has issues related to microcracking caused by expansion and reaction heat, retarder and fibers are proposed to be used to control the hardening rate and cracking.

This paper examines the effect of steel fiber volume fraction on compressive and flexural properties of high-strength concrete with compressive strength of 40 MPa. The fiber volume fractions used in this study consist of 0.5, 0.75 and 1.0%. The prisms with 150x150x550 mm were made and tested in accordance with EN-14651.

In this study, hydration heat, autogenous shrinkage and compressive strength of the specimens has been verified with moisture supply on the hardened cement paste depending upon the difference in moisture condition of the fine aggregates. The result showed that, autogenous shrinkage was significantly reduced and also the compressive strength was improved due to the continuous moisture supply regarding on fine aggregates.

The purpose of this study is to understand a compressive strength and propose a dry shrinkage strain equation being able to predict dry shrinkage of alkali-activated materials(AAM) mortar samples manufactured using fly-ash(FA) and ground granulated blast furnace slag(GGBFS). The main parameters investigated were the GGBFS replace ratios(30, 50, 70 and 100%) and sodium silicate modules(Ms[SiO2/Na2O] 1.0, 1.5 and 2.0). The compressive strength of AAM increased with increases GGBFS replace ratios or Ms contents. The dry shrinkage strain of AAM decreased with increases Ms contents. But, the dry shrinkage strain of AAM increased as the GGBFS replace ratio increases. Therefore, the GGBFS replace ratio seems to have very significant and important consequences for the mix design of the AAM mortar. The results indicated the R-square of single regression analysis based on each mix properties was the highest value; 0.7539~0.9786(average 0.9359). And the presumption equation of dry shrinkage strain with all variables(GGBFS, Ms and material age) has higher accuracy and its R-square was 0.8020 at initial curing temperature 23 degrees Celsius and 0.8018 at initial curuing temperature 70 degrees Celsius.

By analyzing the compressive strength througth field test execution on the shotcrete mixture with 40% blast furnace slag and slurry accelerator, confirmed the suitability as subsea tunnel material. As a result, strength characteristic on the anti-chloride shotcrete is excellent evaluated in terms of compressive strength compared with existing shotcrete.

This study examined the effect of outside temperature on the properties of high-strength concrete to determine conditions for four-season construction. With 20 ℃ as the reference temperature, 20, 30, and 40 ℃ were set as hot weather conditions, and 5, -10, and –20 ℃ as cold weather conditions. Properties as the effect of outside temperature on compressive strength of high-strength concrete was studied.

This paper investigates the strength properties of ground granulated blast furnace slag(GGBFS) with magnesium sulfate(MgSO4). GGBFS was replaced with 1, 2, 3, 4, and 5% MgSO4 by weight. Mixtures of sodium hydroxide(NaOH) and sodium silicate(Na2SiO3) were used as the alkaline activator; a mixture of 5% NaOH and 5% Na2SiO3, and a mixture of 10% NaOH and 10% Na2SiO3 by slag weight. The added activators were dissolved in the water, and the weight ratio of water to slag was 0.45. This study was performed using compressive strength testing, ultrasonic pulse velocity(UPV), water absorption and X-ray diffraction(XRD). In this study, the strength of hardened samples decreases with increasing MgSO4 content. In addition, the water absorption of samples increases and UPV decreases, with the increase of MgSO4 content. Brucite, gypsum and M-S-H(magnesium silicate hydrate) are present in the XRD patterns of the hardened samples.

In this study, Retarder, which shows characteristics of delay hydration reaction and reduce hydration heat in concrete, was processed through granulation and paraffin coat to induce reation by hydration heat. Concrete with Granulated and paraffin coated retarder were prepared and compressive strength was measured by curing at 20℃ and 40℃. As a result, it was confirmed that retarder exhibits performance depending on the curing temperature.

In this study, cement mortar (KS F 4042) used for repairing concrete structures was evaluated for compressive strength and bond strength according to the mixing ratio of polymer. From the experimental results, it was confirmed that as the polymer content increases, the bond strength properties increase, but the compressive strength decreases slightly at a certain rate.