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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Concrete Structures and Materials
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Korea Concrete Institute
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Volume & Issues
Volume 2, Issue 2 - Dec 2008
Volume 2, Issue 1 - Jun 2008
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Adhesion Strength and Other Mechanical Properties of SBR Modified Concrete
Chmielewska, Bogumila ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 3~8
DOI : 10.4334/IJCSM.2008.2.1.003
Polymer-cement composites are known repair materials. The aim of this work is to investigate the influence of various amount of dispersion of carboxylated styrene-butadience copolymer on the selected mechanical properties of polymer-cement concrete (PCC) and on its adhesion to ordinary concrete. The compressive, flexural and tensile strengths as well as frost resistance and fracture resistance of the composites are tested. Adhesion strength of PCC to ordinary concrete, as one of most important performance of good repair material is evaluated and analyzed using three test methods. The results obtained in standard pull-off test are compared with the two other tests. The first one, which is an adaptation of WST (wedge splitting test) characterizes crack propagation in the plane of bond created during repair. In the second test the resistance to shear is a measure of adhesion strength.
Early-Age Properties of Polymer Fiber-Reinforced Concrete
Myers, Daniel ; Kang, Thomas H.K. ; Ramseyer, Chris ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 9~14
DOI : 10.4334/IJCSM.2008.2.1.009
The cracking problem in concrete is widespread and complex. This paper reviews the problem and focuses on those parts of the problem that are more readily solved. Polymer fibers are shown to have promise in several important areas of the cracking problem. To investigate one of these areas of the cracking problem more completely, an experimental research program focusing on the early-age properties of fibers was carried out. This study researched the properties of four polymer fibers; two of the fibers were macrofibers, and two were microfibers. Each fiber was tested at several dosage rates to identify optimum dosage levels. Early-age shrinkage, long-term shrinkage, compressive strength, and tensile strength were investigated. Long-term shrinkage and strength impacts from the polymer fibers were minimal; however, the polymer fibers were shown to have a great impact on early-age shrinkage and a moderate impact on early-age strength.
Comparative Study on Compressive Strength of Concrete with New Sand-Cap and Neoprene Pad
Park, Young-Shik ; Suh, Jin-Kook ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 15~19
DOI : 10.4334/IJCSM.2008.2.1.015
The most typical capping method for concrete structures is a sulfur-mortar compound capping, provided it satisfied the standard criterion set forth by ASTM C 617, but this conventional bonded-type method has many problems. It exhibits relatively the smaller unreliable value of the strength of high-strength concrete due to the differences of elasticity and strength between the cylinder and the cap, and manifests poor serviceability such as dangerous working tasks or a waste of the working time. To prevent these problems, unbonded-type capping methods have taken the place of the conventional methods in recent years. One of the popular methods is the use of synthetic rubber like a neoprene pad. Serious problems still remain in this method, which include the consideration of its chemical characteristics in consideration of the selection, the safekeeping and the economy of the pads. Moreover, the synthetic rubber pads cannot be used in concrete cylinder with strength greater than 80 MPa according to ASTM C 1231-00. New 'sand-capping method' presented in this study, can be applicable to the compressive strength evaluation of the high strength concrete in the range of
. This new method has better simplicity and reliability than those of existing 'sand-box', because usual materials such as standard sand and simply-devised apparatus are used for the capping system. The statistical analysis of the test results revealed that the new sand-capping method exhibited the smallest deviation and dispersion, attesting for its much better reliability than other methods specified in ASTM C 1231/1231M.
Performance of Concrete in Aggressive Environment
Aguiar, Jose B. ; Camoes, Aires ; Moreira, Pedro M. ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 21~25
DOI : 10.4334/IJCSM.2008.2.1.021
Surface treatments act as a barrier between the environment and the concrete, preventing or retarding the entry of harmful substances and cutting off the transportation path into concrete. The effectiveness of a surface protection preventing the permeation depends on how close and strongly connected are the resin molecules. This work intends to contribute to a better understanding of the performance of protected concrete in chemically aggressive environments, by presenting results of ion diffusion and resistance to aggressive solutions of several hydrophobic agents and coatings used to protect concrete. Three different types of surface protections were tested: silicone hydrophobic agent, acrylic and epoxy coatings. The obtained results indicate that the overall performance of epoxy resin was better than the other selected types of protections.
Performance Evaluation of Sprayed Ductile Fiber-Reinforced Mortar as a Repairing Material
Kang, Su-Tae ; Koh, Kyung-Taek ; Ryu, Gum-Sung ; Kim, Jin-Soo ; Han, Cheon-Goo ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 27~33
DOI : 10.4334/IJCSM.2008.2.1.027
Most of existing repair materials have some shortcomings such as brittle fracture, imperfect interface bonding and marked difference in modulus of elasticity compared with the structures. These problems make their repair inefficient. Some researches on using a fiber-reinforced mortar as an alternative to enhance the efficiency have been carried out recently. This paper presents the results of an experimental study on the performance of sprayed PVA fiber-reinforced mortar as a repair material. We evaluated its mechanical properties, durability and strengthening effect. This study shows that the sprayed PVA fiber-reinforced mortar is remarkably effective as a repair material.
Flexural Behavior of Polymer Mortar Permanent Forms Using Methyl Methacrylate Solution of Waste Expanded Polystyrene
Bhutta, M. Aamer Rafique ; Tsuruta, Ken ; Ohama, Yoshihiko ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 35~39
DOI : 10.4334/IJCSM.2008.2.1.035
This experimental study examines the applicability of polymer mortar permanent forms using a methyl methacrylate (MMA) solution of waste expanded polystyrene (EPS) to develop effective recycling processes for the EPS, referring to the flexural behavior of a polymer-impregnated mortar permanent form with almost the same performance as commercial products. An MMA solution of EPS is prepared by dissolving EPS in MMA, and unreinforced and steel fiber-reinforced polymer mortars are mixed using the EPS-MMA-based solution as a liquid resin or binder. Polymer mortar permanent forms (PMPFs) using the EPS-MMA-based polymer mortars without and with steel fiber and crimped wire cloth reinforcements and steel fiber-reinforced polymer-impregnated mortar permanent form (PIMPF) are prepared on trial, and tested for flexural behavior under four-point (third-point) loading. The EPS-MMAbased PMPFs are more ductile than the PIMPF, and have a high load-bearing capacity. Consequently, they can replace PIMPF in practical applications.
Spalling Properties of High Strength Concrete Mixed with Various Mineral Admixtures Subjected to Fire
Han, Cheon-Goo ; Han, Min-Cheol ; Heo, Young-Sun ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 41~48
DOI : 10.4334/IJCSM.2008.2.1.041
This study investigates the spalling properties of high strength concrete designed with various types of mineral admixture and diverse content ratios of polypropylene (PP) fiber. Experimental factors considered in series I are four pozzolan types of mineral admixture and series II consists of three shrinkage reducing types of mineral admixture. PP fiber was added 0.05, 0.10 and 0.15vol. % in each mixture of series I and series II, so that totally 27 specimens including control concretes in each series were prepared. Test results showed that the increase of fiber content decreased the slump flow of fresh concrete and increased or decreased the air content depending on the declining ratio of slump flow. For the properties of compressive strength, all specimens were indicated at around 50 MPa, which is high strength range; especially all specimens in series II were 60 MPa. Fire test was conducted in standard heating curve of ISO 834 with
size of cylinder moulds for 1 hour. The specimens incorporating silica fume exhibited severe spalling and most specimens without the silica fume could be protected from the spalling occurrence in only 0.05vol % of PP fiber content. This fire test results demonstrated that the spalling occurrence in high strength concrete was not only affected by concrete strength related to the porosity of microstructure but also, even more influenced by micro pore structure induced by the mineral admixtures.
PMM for Surface Treatment of Concrete with the Utilization of By-Products
Drochytka, Rostislav ; Zizkova, Nikol ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 49~55
DOI : 10.4334/IJCSM.2008.2.1.049
The disadvantage of PMM's (polymer-modified mortars) that are currently on the market is the utilization of expensive polymer additives and also the cost of the other components. One of the possibilities how to decrease this price is the effective utilization of waste materials which are very inexpensive in spite of their good properties. The combinations of different degree in polymer adhesiveness and waste secondary raw materials - fly ash - are experimentally verified in the paper. The use of fly ash in adhesive materials for ceramic tiles is limited by unsatisfactory initial adhesiveness to sintered ceramic sherd as a result of a running pozzolanic reaction that lowers the efficiency of polymer additives. On the other hand, the use of adhesive and backfill coating materials for gluing ETICS board insulation materials has brought very good results.
Ultimate Strength of Concrete Barrier by the Yield Line Theory
Jeon, Se-Jin ; Choi, Myoung-Sung ; Kim, Young-Jin ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 57~62
DOI : 10.4334/IJCSM.2008.2.1.057
When the yield line theory is used to estimate the ultimate strength of a concrete barrier, it is of primary importance that the correct assumption is made for the failure mode of the barrier. In this study, a static test was performed on two full-scale concrete barrier specimens of Korean standard shape that simulate the actual behavior of a longitudinally continuous barrier. This was conducted in order to verify the failure mode presented in the AASHTO LRFD specification. The resulting shape of the yield lines differed from that presented in AASHTO when subjected to an equivalent crash load. Furthermore, the ultimate strengths of the specimens were lower than the theoretical prediction. The main causes of these differences can be attributed to the characteristics of the barrier shape and to a number of limitations associated with the classical yield line theory. Therefore, a revised failure mode with corresponding prediction equations of the strength were proposed based on the yield lines observed in the test. As a result, a strength that was more comparable to that of the test could be obtained. The proposed procedure can be used to establish more realistic test levels for barriers that have a similar shape.
Early Age Properties of HPC Columns under Construction-Site Conditions
Yun, Ying-Wei ; Jang, Il-Young ;
International Journal of Concrete Structures and Materials, volume 2, issue 1, 2008, Pages 63~68
DOI : 10.4334/IJCSM.2008.2.1.063
High performance concrete (HPC) is widely used in civil engineering due to its high durability and low permeability etc. Compared with ordinary concrete, HPC may develop much higher AS (autogenous shrinkage) at early age due to the relative low water cement (w/c) ratio and adding of mineral admixtures, which is one of the main reasons for early age micro-cracking of HPC structures. This paper studies the early age property of HPC columns under similar construction-site surroundings by embedded strain transducers. Results show that for HPC structure, early-age autogenous shrinkage especially within the first day after concrete pouring is pretty large. AS within the first day are 60% larger than those for 14 days in this research for all specimens. Therefore it should be taken into account for structure durability. By comparison of PHPC (plain HPC column) and RHPC (reinforced HPC column) specimens, the effects of reinforced bars on AS and temperature distribution have been analyzed. Also the influence of w/c ratio on AS is demonstrated.