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.

In general, polymer cement mortars that is made from organic polymer dispersion and cement have good workability compared with ordinary cement due to ball-bearing acting of polymer particles in cement mortar. The purpose of this study is to evaluate the workability of cement mortar according to adding of admixtures such as polymer dispersions, blast-furnace slag and fly ash. From the test results, the flow of polymer-modified mortars is increased with increasing polymer-cement ratio, and also is a little improved according to adding of fly ash compared to blast-furnace slag.

In this study, Early compressive strength analysis of low carbon mortar using industrial byproducts and describes relationships between strength property and CO2 indices to evaluate eco-efficient of low carbon binder mortar. Based on the results, this study is to give fundamental data for ability of eco-efficient low carbon binder.

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.

Research on concrete using activated Hwang-Toh is intensively conducted to protect environment. Therefore, in this study, the effect of activation of Hwang-Toh on strength was investigated through flexural and compressive tests. The specimen made by replacing part of cement with inactivated Hwang-Toh showed strength 55~61% of the control specimen. However, the specimen with activated Hwang-Toh as alternative material indicated load-carrying capacity 76~102% in comparison with the control specimen. Hence, concrete with activated yellow soil can be use in the construction market.

It is necessary to investigate the possibility of high density material as an ingredient in the manufacturing of radiation shielding material. In this study, the suitability of heavy weight waste glass as a shielding material is considered. From the results, it was found that when the heavy weight waste glass substitution ratio increases, radiation shielding performance also increase

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 paper investigates the effect of amount of Paraffin-encapsulated phase change material (PCM) on the thermal energy storage of cement mortar for developing energy saving concrete. The PCM with melting point of 44℃ was used in this study. The added amounts of PCM in the cement mortar were 0, 10, 20 and 30% of cement weight. The results indicated that the heat storage properties of cement mortar was improved with increasing contents of PCM.

As interest in sustainable concrete increases, research on replacing cement with alternative materials has been actively conducted. Therefore, in this study, flexural and compressive tests were carried out using sustainable specimens fabricated by replacing part of cement with blast furnace slag and activated Hwang-Toh as alternative materials and control specimen. Based on the test results, the specimen with blast furnace slag showed the best load-carrying capacity. Compared with the control specimen, the specimen with activated Hwang-Toh indicated about 94.8~102.1% load-carrying capacity. Thus, it appears that the sustainable concrete can be practically used in the construction field.

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

본 논문은 폴리머 모르타르로 보수된 철근콘크리트 보의 휨거동을 실험적 ·해석적으로 분석한 결과를 제시한다. 실험적 연구에서 는 보수위치, 모르타르 재령을 실험변수로 고려하여 제작된 13개의 보에 대한 3점 휨실험이 실시되었다. 인장측 및 압축측을 보수한 실험체들 의 파괴는 모르타르와 콘크리트의 계면에서 발생하지 않았으며, 폴리머 모르타르의 인장변형률이 극한변형률을 초과하는 순간 발생하였다. 압축측을 보강한 실험체들은 기준실험체의 최대하중과 유사하였다. 그들의 연성지수는 기준실험체보다 훨씬 컸다. 인장측을 보수한 실험체 는 매우 취성적으로 파괴되었으며, 연성지수가 크게 감소하였다. 폴리머 모르타르로 보수된 철근콘크리트의 보의 휨거동을 예측하기 위해 Opensees을 사용한 재료비선형 해석을 진행하였다. 해석 모델을 단순화하기 위해 2차원 골조요소를 적용하였으며, 재료 비선형성을 고려하기 위해 파이버 모델을 적용하였다. 해석결과는 비선형 구조해석은 압축측 보수 실험체의 휨거동을 적절하게 예측하나, 인장측 휨거동는 다소 과 대 평가하는 것으로 나타났다.

This study investigated the compressive strength characteristics of concrete and mortar containing waste pottery fine powder. To identify the effects of waste pottery fine powder on the compressive strength of concrete and mortar, cement was replaced with waste pottery fine powder at 5, 10 and 15% rates and the variations in compressive strength were evaluated. For high strength concrete, compared with a control mix, 5% replacement resulted in the reduction of 3.4% in compressive strength at 7 days; however, at 28 days, the strength actually increased by 2.5%. For normal strength concrete, compared with a control mix, 5% replacement resulted in the reduction of 20.4% in compressive strength at 7 days, and 14% reduction at 28 days. As for the mortar, at 5% replacement, compared with a control mortar mix, compressive strength of mortar decreased by 3% at 7 days, while an increase of 5.9% was observed at 28 days. Therefore, the optimum replacement rate of cement with waste pottery fine powder appears to be 5%.

본 논문은 바탕면의 함수조건에 따른 보수재료로서 MKPC의 인발 부착강도, 전단 부착강도, 계면 부착강도를 폴리머 시멘트 모르 타르, 에폭시 모르타르와 비교 분석하였다. 그 결과 MKPC는 PC 및 MKPC와 비교하여 바탕면 함수조건에 따른 부착성능의 변화가 상대적으 로 작은 것으로 나타났다. 또한 MKPC의 경우 절건 바탕면에서의 부착성능은 무기계 보수재료인 폴리머 시멘트 모르타르와 비교하여 우수한 특성을 지니고 있으며, 습윤 바탕면에서의 부착성능은 폴리머 시멘트 모르타르와 유사한 수준을 보이고 있으나 에폭시 모르타르와 비교하여 우수한 특성을 지니는 것으로 나타났다.

The quantities of low-grade reject fly ash (RFA) and paper sludge ash (PSA) generated are increasing annually and causing a serious social problem. In this study, the utility of these by-products was analyzed by using RFA and PSA as mineral admixtures. RFA-PSA blended mortar was fabricated and evaluated for use as a cement additive. RFA was milled to improve workability and the hydration reaction, and PSA was mixed with anhydrite to create the ettringite. As the RFA-PSA blended powder replaced 10% of the cement by weight, compressive strength of the mortar exceeded that of ordinary mortar prepared with Portland cement (OPC). Length change (28 days) of the RFA-PSA mortar with a 10% replacement rate was 68% of the OPC mortar and was 62% with a 30% replacement rate.

이 연구에서는, 우리나라 전통 건축재료 중 하나인 천연 황토 모르타르에 사용되어 온 해초풀과 현대적 재료인 고흡수성수지 (Superabsorbent Polymer, SAP)와 같은 흡수성 물질이 이러한 모르타르의 건조수축과 압축강도에 미치는 영향이 조사되었다. 흡수성 물질과 더불어 문화재표준시방서에서 권고하는 초기 밀봉양생의 효과 역시 검토되었다. 실험에 의한 28일 압축강도와 수렴한 건조수축 변형율의 검 토 결과, 우선 초기 7일간의 밀봉 양생은 강도향상과 수축저감에 효과적이었다. 따라서, 문화재표준시방서의 권고는 합리적이며 실효성이 있 는 것으로 검증된다. 흡수성 물질의 혼입 역시 두 재료특성에 있어 효과적인데, 그 효과는 물질들의 흡수 능력에 의존한다. 따라서, 흡수 능력이 더 높은 SAP을 사용하는 것이 해초풀을 사용하는 것보다 더 효과적이다. 그러나, 이러한 것들이 유효하기 위해서는 초기 밀봉양생과 물이 추가 되지 않는 조건들이 함께 따라야 한다. 마지막으로, 황토 모르타르의 압축강도의 증가는 건조수축의 감소와 선형적으로 관계한다. 이러한 선형 상관성에 의해, 초기밀봉 양생 또는 흡수성 물질의 혼입에 따른 모르타르의 압축강도 증가하는 원인이 정량적으로 설명될 수 있다.

Compressive strength characteristics of mortar containing waste pottery fine powder were investigated in this study. The experimental variables selected were 5, 10, and 15 percent replacements of cement with waste pottery fine powder. The findings are summarized as follows: (1) compared with the strength of the control specimens with no replacement rate, compressive strength of the mortar at 7days decreased by 3% and 9.3%, respectively at 5% and 10% replacement rate of cement with waste pottery fine powder, but (2) compressive strength of the mortar at 28days increased by 5.9% and 6.9%.

In this study, we tried to review the potential of commercialization of the developed product of aerated concrete and floor mortar used in the construction of residential buildings such as apartment buildings. As a result, it was analyzed that the difference was negligent in terms of the depth of subsidence, though the developed product was good enough in terms of compressive strength and economic efficiency.

In this research, the adverse effect of various oils when the mortar including fly ash was submerged into the oils. From the experimental results, the highest length and mass changing rates were observed when the mortar was submerged into the biodiesel and in the case of relative dynamic elastic modulus, soy oil and biodiesel caused the most decreasing. Additionally, the mortar with fly ash was influenced more than ordinary Portland cement when it submerged into the oil.

In this study, to evaluate the performance of fire resistance of the mortar with magnesium hydroxide(MH) and aluminium hydroxide(AH) which has a RCC (Radiant Control Capability) as repair material to the steel structure, temperature evaluation of mortar was conducted by increasing 500°C in the furnace. The performance of RCC can decrease a temperature to external and internal mortar. As a result, it is confirmed that temperatures of mortar with magnesium hydroxide(MH) and aluminium hydroxide(AH) were more decreased than general mortar due to the RCC effect of MH and AH. Therefore, it can be possible to apply to a repair material at the steel structure.

The purpose of this study is to assess the strengthening effect of fiber-reinforced polymer(FRP) grids on flexural members. For this purpose, experimental study was conducted using seven flexural specimens with the main variables of an FRP grid and inorganic mortar used as adhesive. All the specimens failed due to the tensile rupture of FRP grids without debonding between FRP grids and inorganic mortar. It was found that the strengthening effect was dependent on the material properties of FRP grids.