• International Journal of Highway Engineering
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• v.14 no.5
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• pp.93-99
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• 2012

PURPOSES: The purpose of this study is to compare the alkali-silica reactivity for mortar bar and concrete prism specimens using crushed aggregates of 5 types in Korea. And the alkali-silica reactivity for those aggregates are measured by chemical test method. METHODS: The alkali-silica reactivity for those aggregates was measured by chemical test method of KS F 2545, mortar-bar test of KS F 2546, accelerated mortar-bar test method of ASTM C 1260 and concrete prism test method of ASTM C 1293, relatively. RESULTS: The alkali-silica reactivity for those aggregates was verified by chemical test of KS F 2546 and accelerated mortar-bar test of ASTM C 1260. However, it was not by mortar-bar test of KS F 2546 and concrete prism test of ASTM C 1293. CONCLUSIONS: The above results showed that relationship among the four test methods were very low. The results from 3 types of test methods using cement-aggregate combinations appeared to be different. Because the environmental conditions of test methods for measuring the alkali-silica reactivity such as equivalent alkali content(external source), humidity, temperature, and times were different though the aggregates were same. Moreover, alkali-silica reactivity showed the biggest impact when alkalis were supplied form outside and exposed to environmental conditions. The accelerated mortar-bar test method seems to be most appropriate test method for concrete structures exposed to alkali environment.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.663-666
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• 1999

Ground Penetrating Radar (GPR) attached with 1 GHz center frequency antenna has been used to measure a dielectric constant of mortar, and to detect and locate a steel bar embedded inside laboratory size mortar specimens at various depth. Mortar specimens are made for the measurements with the dimensions of 100cm (width)$\times$100cm (length)$\times$14cm (depth). Each specimen has a 13mm diameter D13 steel bar at 2, 4, 6, 8, 10 and 12cm depth. In this paper, results of radar measurments are provided with a sample output, which successfully located the bar. It has been found that the reflected wave of the steel bar interacts with that of surface when the steel bar has the close distance to the surface.

• International Journal of Concrete Structures and Materials
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• v.4 no.2
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• pp.119-125
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• 2010

In this study, the effects of the fineness modulus of reactive aggregate on ASR expansion and ASR products have been investigated. The reactive aggregate used was metamorphic aggregate originated from Korea. ASR tests were conducted according to accelerated mortar bar test. The morphology and chemical composition of products formed in mortar bars, 5 years after the mortar bar test had been performed, were studied by scanning electron microscopy equipped with energy dispersive spectroscopy. Test results indicated that ASR expansion of mortar bars decrease in linear proportion to the fineness modulus of reactive aggregate. SEM images indicated that mortar bars showed reactive products formed in cement paste, within air voids and within cracks through particles except for the mortar bar with the fineness modulus of 3.25. The EDS analysis of the reactive products showed presence of silica, calcium and sodium, typical of ASR product composition.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.447-450
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• 1994

The chemical method and mortar-bar method for identification of the susceptibility to Alkali-Aggregate Reaction (AAR) was established as KS method by referencing the ASTM methods. However, the chemical method requires skilled chemical engineers and aggregates are tested in very severe condition, and on the other hand, the mortar-bar method needs a long time of 3 or 6 months. Judging from this circumstance that the use of crushed stones are increased due to the shortage of natural aggregates, the development and standardization of a new rapid test method is considered essential. The purpose of this paper is to research for the possibility to apply the rapid method, instead of the chemical method and the mortar-bar method with using the several domestic crushed stones.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.793-796
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• 2004

In domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation. chemical decay et. being developed and applied. However, present polymer cement mortar applied to section restoration system cause the problem of long-term working and economica] efficiency. because that is divided into two process of liquid corrosion prevention agent and polymer cement mortar. In this background, accelerated test with due regard to $3\%$ NaCl soaking and autoclave cure was performed to confirm steel bar corrosion prevention properties of polymer cement mortar mixed with corrosion prevention agent of powdered type. In conclusion. we confirmed application possibility and excellency of steel bar corrosion prevention properties of polymer cement mortar mixed with corrosion prevention agent of powdered type comparing general polymer cement mortar applied to section restoration system of present study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.27-34
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• 2012

The objective of this study is to evaluate the stiffness of mortar-filled sleeve bar splice using estimation method of failure mode in the sleeve reinforcement splice. To attain this goal, we analyzed the test results of 261 actual-sized mortar-filled sleeve splice specimens. The study results showed that the estimation method of the failure mode in mortar-filled sleeve bar splice made an effective estimate of the stiffness in this bar splice with the exception of specimens with SD500 bars and smooth pipe sleeve. Especially, of the specimens with cast sleeve or uneven pipe sleeve in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, specimens over 98% with SD400 bars and all specimens with SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in monotonic loading. In addition, of the specimens in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, all specimens with SD400 bars and SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in cyclic loading.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.180-192
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• 2008

The purpose of this research is to evaluate the structural performance of mortar-filled ductile cast iron sleeve splice developed for SD500 high-strength reinforcing bar under cyclic loading. The test variables adopted in this study are the development length of bar, compressive strength of mortar, bar size, sleeve types and others. In this research, it is showed that the mortar-filled sleeve splice for SD500 high-strength bar satisfied the structural performance required in ACI, AIJ code as well as domestic code. Also the results of experimental research presented in this paper provided basic engineering data for developing a reasonable design method of mortar-filled sleeve splice for SD500 high-strength reinforcing bar.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.531-537
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• 2009

In this study alkali reactivity of crushed stone was conducted according to the ASTM C 227 that is traditional mortar bar test, and C 1260 that is accelerated mortar bar test method. The morphology and chemical composition of products formed in mortar bar, 3 years after the mortar bar tests had been performed, were examined using scanning electron microscopy (SEM) with secondary electron imaging (SEI) and electron probe microanalysis (EPMA) with backscattered electron imaging (BSEI). The crushed stone used in this study was not identified as being reactive by ASTM C 227. However, mortar bars exceeded the limit for deleterious expansion in accelerated mortar bar test used KOH solution. The result of SEM (SEI) analysis, after the ASTM C 227 mortar bar test, confirmed that there were no reactive products and evidence of reaction between aggregate particles and cement paste. However, mortar bars exposed to alkali solution (KOH) indicated that crystallized products having rosette morphology were observed in the interior wall of pores. EPMA results of mortar bar by ASTM C 227 indicated that white dots were observed on the surface of particles and these products were identified as Al-ASR gels. It can be considered that the mortar bar by ASTM C 227 started to appear sign of alkali-silica reaction in normal condition. EPMA results of the mortar bar by ASTM C 1260 showed the gel accumulated in the pores and diffused in to the cement matrix through cracks, and gel in the pores were found to be richer in calcium compared to gel in cracks within aggregate particles. In this experimental study, damages to mortar bars due to alkali-silica reaction (ASR) were observed. Due to the increasing needs of crushed stones, it is considered that specifications and guidelines to prevent ASR in new concrete should be developed.

• Architectural research
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• v.10 no.2
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• pp.27-35
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• 2008

Because of several advantages of mortar-filled sleeve splice in reinforced concrete buildings, this method is being applied increasingly at construction sites and various methods of the splice have been developed in Korea and other countries. In order to apply this system in the field, studies on mortar-filled sleeve splice have been mainly experimental research focused on overall structural performance. However, for understanding the structural characteristics of this splice more accurately, we need to study the confining effect of sleeve, which is known to affect bond strength between filling mortar and reinforcing bar, the most important structural elements of the bar splice. Thus, in order to examine the confinement effect of mortar-filled steel pipe sleeve splice, the present study prepared actual-size specimens of steel pipe sleeve splice, and conducted a loading. Using the test results, we analyzed how the confining effect of steel pipe sleeve affects the bond strength of this splice and obtained data for developing more reasonable methods of designing the splice of reinforcement.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.508-513
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• 1996

The purpose of this paper, having chosen the connection method, filled by High-strength mortar, in conncetion of PC member, is to study the mechanical behaviour and practical usage of the method. The paper estimates the connection ability of Reinforced-bar, that is, Sleeve considering the effect of Reinforced-bar's dimeter. Sleeve's length and diameter in the structural behaviour of mortar-filled connection, therefore the behaviour of Splice-Sleeve exists in concrete practically. This paper discusses the effect of the concrete in Splice-Sleeve. Also, to estimate structural behaviour in a practical wall panel, the upper and bottom wall panels are produced and the behaviour of Splice-Sleeve is discussed. And then Vertical Tie Bar being designed by using Precast method, this paper presents the various application and the practicable method using Splice-Sleeve.