본 연구에서는 코어직경에 따른 시멘트 모르타르의 부착강도 변동 특성을 분석하기 위하여, 코어직경 50mm 부착강도 13개 데이터와 코어직경 75mm 부착강도 17개 데이터를 활용하여 분석하였다. 부착강도의 평균값을 비교하면 코어직경 75mm의 값이 코어직경 50mm의 값에 비해 10.5% 정도 크게 나타났으며, 코어직경에 따른 부착강도의 변동계수(Coefficient of Variation) 값을 비교·분석한 결과 코어직경 75mm의 변동계수가 모든 시험 회차에서 상대적으로 작게 나타났다. 그러므로, 코어 직경에 따른 부착강도의 변동성을 최소화 하기 위해서는 코어직경 75mm를 사용하는 것이 바람직할 것으로 판단된다.

In this study, presents the mechanical bond strength properties of mortar using bio polymer in seaweed. The evaluation was based on the method presented in KS F 2762. It was confirmed that the resistance performance all levels of biopolymer using mortar excellent performance with bond strength over 1.0 MPa as defined in KS F 4042 『Polymer-cement mortar for Concrete Structures』.

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 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.

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.

This study aimed to describe the mechanism and reaction characteristics of the adhered mortar removal of recycled aggregate (RA) using microwave irradiation (700 W) and a mixed solution of HCl and H2O2. The HOCl concentration increased to 29.7 M at 35oC and 40 min of reaction time without RA in the mixed solution, which shows that HCl reacts with H2O2 to form HOCl and water. However, after nitrogen purging, the HOCl concentration decreased to 2.71 M in 20 min, which proves indirectly that HOCl reacts with HCl to form Cl2 and water. The HOCl concentration decreased from 29.7 M to 1.88 M at 35oC in 40 min with RA in the mixed solution, and the Ca2+ concentration increased to 9,750 mg/L, which demonstrates indirectly that mortar mainly composed of Ca(OH)2 reacts with Cl2 to form Ca(OCl)2 and CaCl2. The reaction rate (k) with microwave heating was about 2.3 times faster than that with conventional heating, and k at a reaction temperature of 50oC was about 1.3 times faster than that at 35oC. The treated RA was improved in density, water absorption, abrasion loss, and absolute volume.

This study aimed to determine adhered mortar content of recycled aggregate (RA) using microwave irradiation (700W)and mixed solution of hydrochloric acid (HCl) and hydrogen peroxide (H2O2). The optimum condition was first to soakRA in tap water for 30 min and then RA was soaked in mixed solution of 30% HCl and 15% H2O2 (HCl:H2O2=1:2) for 70-90min after 15-min microwave irradiation. The mortar of RA in the condition was completely removed within2.3 hrs. Reaction rate (k) with the condition was −0.6408hr−1, which was about 190 times faster than that with HCl only(k=−0.0034hr−1).

We conducted this study to develope technique for removing fine mortar attached to waste reinforcing steel bar (D13). We observed the effect of the glycolic acid concentration (10 ~ 40%) and reaction time (0.5 ~ 4 hr) on the mortar removal. The reaction rate (−1.3089 hr−1) was the fastest at 20% of glycolic acid. The mortar was completely removed in 3 hrs. The reaction rate decreased with pH increase (1.4 ~ 2.0) at 20% of glycolic acid.

The purpose of this study is to develop eco-friendly finishing materials of acrylic emulsion-modified mortars using lightweight aggregate carrier which contains pyroligneous liquid. Four types of light-weight aggregate carriers such as perlite, vermiculite, charcoal and zeolite are selected. The acrylic emulsion-modified mortars are prepared with light-weight carrier replacements to dolomite of 0, 5, 10, 15, 20%, and tested for flowability, adhesion in tension, water absorption coefficient and antibiosis. As a result, the flowability of acrylic emulsion-modified mortars using zeolite light-weight is improved with increasing light-weight carrier content. The adhesion in tension of acrylic emulsion-modified mortars using lightweight carrier is satisfied with KS requirement. Especially, the adhesion in tension of acrylic emulsion-modified mortars using light-weight aggregate carrier at a high temperature of 40oC are better than the low temperatures of 0oC and 20oC. The water absorption coefficient of acrylic emulsion-modified mortars using light-weight aggregate carriers is increased with increasing light-weight carrier content. However, the water absorption coefficient is satisfied with KS requirement. The antibiosis of acrylic emulsion-modified mortars using zeolite light-weight carrier is remarkably improved with increasing light-weight carrier content.

Experiments were divided into two parts; one part is to understand the basic properties of high flowable VA/VeoVa-modified cement mortar with different polymer cement ratio (P/C) and the weight ratio of fine aggregate to cement (C:F) and the other part is to investigate the effect of surface water spread on the concrete substrate on adhesion in tension. To understand the basic performance, the specimens were prepared with proportionally mixing VA/VeoVa redispersible powder, ordinary portland cement, silica sand, superplasticizer and viscosity enhancing agent. Here, P/C were 10, 20, 30, 50 and 75% and C:F were 1:1 and 1:3. As the change of P/C and C:F unit weight, flow test, crack resistance and adhesion in tension were measured. Three specimens with good adhesion properties were selected among specimens with different P/C and C:F. The effect of surface water evenly sprayed on concrete substrate on adhesive strength is investigated. The results show that surface water on concrete substrate increases the adhesion in tension of high flowable VA/VeoVa-modified cement mortar and additionally improves the flowability compared to the non-sprayed case.

본 연구에서는 고유동성의 SBR 개질 시멘트 모르타르의 기초적 성능을 바탕으로 콘크리트의 보수용 재료에 매우 중요한 요구성능인 부착강도에 대한 피착체의 표면에 존재하는 표면수량의 영향을 검토하는 연구가 수행하였다. 고유동성 SBR 개질 시멘트 모르타르의 기초적인 성능을 토대로 부착강도, 잔갈림성, 재료분리 저항성이 좋은 시험체를 선택하였다. 시험체는 C:F=1:1인 경우 P/C=20%, 30%의 시험체 2개, C:F=1:3인 경우 P/C=50%의 시험체 1개, 총 3개가 선택되었으며 이 3개의 배합에 대하여 피착체의 표면수량에 따른 고유동성 SBR 개질 시멘트 모르타르의 특성을 파악하였다. 표면수는 콘크리트 피착면의 단위 면적 (cm2) 당 각각 0, 0.006, 0.012, 0.017, 0.024 g이 균등하게 살포되었으며, 이에 따른 연도변화, 플로우값, 부착강도, 부착파괴형상, 내균열성 및 재료분리여부를 파악하였다. 본 연구를 통해 콘크리트 피착체에 살포된 표면수는 고유동성 SBR 개질 시멘트 모르타르의 부착강도를 증진하는 효과가 있다는 결론을 얻었다.

폴리머시멘트 모르타르는 고강도 및 고내구성 등의 우수한 재료적 성질을 가지고 있어 철근콘크리트 구조물의 보수재료로 광범위하게 사용되어져 왔다. 폴리머시멘트 모르타르와 콘크리트 사이의 부착거동은 폴리머시멘트 모르타르에 의해 보수․보강된 철근콘크리트 부재의 보강성능을 좌우하는 매우 중요한 요소이다. 따라서 폴리머시멘트 모르타르와 콘크리트 접합면에서 발생되는 부착파괴의 메커니즘은 명확히 구명될 필요가 있다. 본 연구에서는 직접인발시험을 통해 국내에서 판매되는 폴리머시멘트모르타르와 콘크리트의 부착강도를 평가하였다. 표준, 침수, 온냉반복 및 동결융해 등의 전처리 조건에 노출된 폴리머시멘트 모르타르의 부착강도를 실내시험을 통해 평가하였으며, 2차에 걸친 시험시공을 통한 현장부착강도도 함께 평가하였다. 시험결과 현장부착강도는 표준조건에서 실시한 실내 부착강도 시험결과보다 낮은 수준이었으며, 열충격조건에서의 실내시험결과와 유사한 것으로 나타났다. 본 연구결과를 기초로 KS에 규정된 폴리머시멘트모르타르의 시험방법 및 품질기준의 타당성을 검토하였다.