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연규석 ( Yeon Kyu-seok ),이현종 ( Lee Hyun-jong ),유능환 ( Ryu Neung-hwan ),김성기 ( Jin Xing-qi ),이지원 ( Lee Chi-won ) 한국농공학회 2005 한국농공학회 학술대회초록집 Vol.2005 No.-
Prepacked polymer mortar that is mainly composed of MMA monomer and used for the patching and restoring materials of concrete structures was developed, and its hardening and strength properties were experimentally surveyed. Results of study show that the permeance of binder into the aggregate was excellent for the case of PMMA mixing ratio of below 10%, the surface hardening inferiority was not generated for the case of the ratio of over 5%. Working time of the prepacked polymer mortar and hardening shrinkage tended to decrease as the PMMA mixing ratio increased. On the other hand, the ratio turned out not to decisively affect on compressive and flexural strengths. Regardless of PMMA mixing content, the adhesive strength was about 2.5 MPa. Occurring the desquamation on the substrate of cement concrete showed the adhesive strength of MMA prepact polymer mortar was excellent.
톱밥을 이용(利用)한 네일링 콘크리트의 기초적(基礎的) 성질(性質)
연규석 ( Yeon Kyu Seok ) 한국농공학회 1987 韓國農工學會誌 : 전원과 자원 Vol.29 No.1
The objective of this study was to obtain basic data which can be applied to the use of nailing concrete using sawdust. The data results from an investigation of fundamental properties of nailing concrete using sawdust from pine native to Korea (Pinus densiflora S. et Z.). This data was then used to examine the effects of varying the mixing ratio of cement, sand, sawdust and water-cement ratio. Results of this study are summarized as follows; 1. The flow values varied between 22 to 108 per cent. To obtain these values, water-cement ratios required were 85 to 95 per cent and 100 to 120 per cent at the sawdust proportions of 0.2 and 0.3, respectively. 2. The specific gravities ranged from 1.09 to 1.43, which were lower than conventional concrete or mortar. This demonstrated the feasibility of making a light weight concrete for nailing using sawdust. 3. The water absorption was 25 to 30 per cent which was obviously higher values than for conventional concrete or mortar. Therefore, it may be concluded that nailing concrete using sawdust would not be recommended for use as a structural material exposed to water. 4. The Shore hardness was measured at 9.4 to 12. 6. These values were larger as the sawdust proportion, water-cement ratio, cement-sand proportion became smaller. 5. The compressive strength ranges were 18 to 51kg/㎠, 25 to 62kg/㎠ and 32 to 76 kg/㎠ at the age of 7-days, 14-days and 28-days, reapectively. The Shore hardness values became larger as the sawdust propertion, water-cement ratio, cement-sand propertion became smaller. 6. The resistance to nail driving and extraction were 5.9 to 13.3kg/cm and 4.1 to 15.2 kg/cm, respectively. The resistance to nail extraction was higher than that to nail driving at the 1 : 1 mixing ratio of cement to sand, resistances to nail driving and extraction were nearly equal at the 1 : 1.5 mixing ratio of cement to sand, and resistances to nail extraction was lower than that to nail driving at the 1 : 2 mixing ratio of cement to sand. It was confirmed that a mixing ratio of cement to sand smaller than 1 : 1.5 would be required in order to keep the bearing power of nail in designs for nailing concrete using sawdust.
연규석 ( Yeon Kyu-seok ),최윤상 ( Choi Yoon-sang ),이재철 ( Yi Jaichul ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-
Polymer concrete is mainly used for the precast products for laying under the ground because it has excellent strength and durability comparing to the cement concrete. In this study, MMA is used to improve the quality of unsaturated polyester polymer concrete. The unsaturated polyester polymer concrete is used to make panel specimens reinforced by FRP. Tests were carried out to survey the effect of FRP reinforcement according to thickness of the panels. The width and length of panel specimens are 20 cm and 100 cm, respectively, and the thicknesses of polymer concretes are 60, 80, and 100 mm. The thicknesses of FRP reinforcements are 0, 1.0, 1.5, 2.0, 2.5, and 3.0 mm. For each specimen, the load-deflection curves and other related physical properties were obtained to survey the flexure characteristics of FRP-reinforcement polymer concrete panels.
연규석 ( Yeon Kyu Seok ),권윤환 ( Kwon Yoon Hwan ),유근우 ( Ryu Keun Woo ),김남길 ( Jin Nan Ji ) 한국농공학회 2001 한국농공학회 학술대회초록집 Vol.2001 No.-
This study was performed to evaluate the internal and external factors affecting external strength of the 3-layer polymer composite pipes made of polymer mortar and fiber--glass reinforced plastic. Twenty four sandwich type 3-layer polymer composite pipes were made of polymer mortar and fiber-glass reinforced plastic by centrifugal method. The objective of this study was to evaluate the effects the of polymer mortar thickness for and core fiber-glass contents per unit area on external strength of 3-layer polymer composite pipes. For the more economical and practical design of 3-layer polymer composite pipe, further study should be done for the various polymer mortar, fiber-glass and different ratio of the inside/outside FRP thickness.
연규석 ( Yeon Kyu Seok ),김관호 ( Kim Kwan Ho ),김기락 ( Kim Ki Rak ) 한국농공학회 1998 한국농공학회 학술대회초록집 Vol.1998 No.-
While a little research has been peformed on flexural behavior of reinforced polymer concrete (RPC)beams with the compressive strength lower than 900kg/㎠ vary little exists in conjunction with the behavior of RPC 1,000kg/㎠ or higher in compressive strength. In this paper the flexural performance of high strength polymer concrete beams with 1,450kg/㎠ in compressive strength was evaluated. The unsaturated polyester resin was used to make polymer concrete as binder. The beams with stirrup singly/doubly were tested to examine the effect of tensile reinforcement ratio. As test results, reinforcement ratio increased with the increase moment strength, decreased with ultimate deflection, ductility index.