• Computers and Concrete
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• v.3 no.4
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• pp.249-260
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• 2006

Self-consolidating concrete (SCC) in the fresh state is known for its excellent deformability, high resistance to segregation, and use, without applying vibration, in congested reinforced concrete structures characterized by difficult casting conditions. Such a concrete can be obtained by incorporating either mineral or chemical admixtures. This paper presents the results of an investigation to asses the applicability of Abram's law in predicting the compressive strength of SCC to any given age. Abram's law is based on the assumption that the strength of concrete with a specific type of aggregate at given age cured at a prescribed temperature depends primarily on the water-to-cement ratio (W/C). It is doubtful that such W/C law is applicable to concrete mixes with mineral or chemical admixtures as is the case for SCC where water to binder ratio (W/B) is used instead of W/C as the basis for mix design. Strength data of various types of SCC mixtures is collected from different sources to check the performance of Abram's law. An attempt has been made to generalize Abram's law by using various optimization methodologies on collected strength data of various SCC mixtures. A set of generalized equations is developed for the prediction of SCC strength at various ages. The performance of generalized equations is found better than original Abram's equations.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.241-244
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• 2004

The evaluation of Single or multi-degregation of concrete coated by high performance surface penetration agency was examined through various tests, i.e., carbonation, absorption, carbonation + chloride ion and carbonation + chemical solution according to various high performance surface penetration agencies and various compressive strengths of base concrete. The 2 types of high performance surface penetration agencies were used i.e., inorganic and alcohol soluble. And 2 types of compressive strength of base concrete were used such as 21 30. MPa. The characteristics of concrete coated high performance surface penetration agency was more improved than that of non-coated concrete, and especially, water soluble inorganic agency was most effective. And if compressive strength of base concrete was low, the improved effects would be larger.

• Land and Housing Review
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• v.2 no.4
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• pp.471-477
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• 2011

This paper will describe the experimental results on the shear behaviors of reinforced concrete (RC) beam with recycled coarse aggregate (RCA). The primary objective of this research is to evaluate the influences of different RCA replacement percentage (i.e, 0%, 30%, 60%, and 100%) on the shear performance of reinforced concrete beams without shear reinforcement. Eight large-scale RC beams without shear reinforcement were manufactured and tested to shear failure. All had a rectangular cross-section with 400mm width ${\times}$ 600mm depth and 6000mm length, and were tested with a shear span-to-depth of 5.1. The results showed that the deflection and shear strength were little affected by the different RCA replacement percentage. Actual shear strength of each RCA beam was compared with the shear strength predicted using the provisions of ACI 318 code and Zsutty'e equation for shear design of RC beams. ACI 318 code predicted the shear strength of RCA reinforced concrete beams well.

• Journal of the Korea Institute of Building Construction
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• v.15 no.6
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• pp.545-551
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• 2015

The aim of this research is suggesting application method of the wasted rock obtained from the limestone quarry of raw material for cement as a coarse aggregate for high strength concrete after crushing and sieving processes. The wasted rock has been normally wasted because of its low quality as a material for cement production. In this research, the concrete using this wasted limestone coarse aggregate was evaluated the constructability based on the performances of workability, air content, and compressive strength. From the experiment, a favorable performance was achieved with a limestone coarse aggregate for high strength concrete comparing to the high strength concrete using granite coarse aggregate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.1
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• pp.85-92
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• 2000

Recently. there has been steadily applied in high-performance concrete using powder type admixture in construction field. It has been reported that high-performance concrete is likely to cause the spalling by fire more seriously due to the dense microstructure. In this paper, spalling properties of high-performance concrete with the kinds of admixture and polypropylene(PP) fiber contents are presented. According to the experimental results concrete contained no PP fiber take place in the form of the surface spalling, regardless of admixture. Concrete contained more than 0.05% of PP fiber and admixture do not take place the spalling, however the concrete using silica fume do spalling. Concrete using blast furnace slag have good performance in spalling resistance. It is found that residual compressive strength has 60~70% of its original strength when spalling do not occur. Although specimens after exposed at high temperature are cured at water for 28days, they do not recover their original strength.

• Advances in concrete construction
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• v.7 no.4
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• pp.219-229
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• 2019

This paper presents an experimental study on the structural performance of an innovative ultra-high performance fiber reinforced concrete (UHPFRC) deck with coarse aggregate of composite bridge under shear force. Test parameters included curing method and shear span-to-height ratio. Test results indicated that more short fine cracks developed beside the existing cracks due to the randomly dispersed fibers, resulting in re-distributing and homogenizing of the concrete stress beside cracks and allowing for the occurrence of more cracks with small spacing compared to normal strength concrete beams. Curing methods, incorporating steam curing and natural curing, did not have obvious effect on the nominal bending cracking strength and the ultimate strength of the test specimens. Shear reinforcement need not be provided for UHPFRC decks with a fiber volume fraction of 2%. UHPFRC decks showed superior load resistance ability after the appearance of cracks and excellent post-cracking deformability. Lastly, the current shear provisions were evaluated by the test results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.55-56
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• 2014

In this research, the effect of types of aggregate and SP on fundamental properties of ultra-high performance concrete of 80 MPa of compressive strength was evaluated to provide solution for high cost of ultra-high performance concrete. As the results of a series of tests, the mixture using limestone and silica aggregates showed improved workability rather than the mixture using granite aggregate. For compressive strength of UHPC, the UHPC mixtures using limestone and silica aggregates showed higher compressive strength than the UHPC mixture using granite aggregate while all mixtures satisfied target compressive range.

• Computers and Concrete
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• v.29 no.6
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• pp.407-418
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• 2022

This paper numerically investigates the effect of changes in the mechanical properties (displacement, strain, and stress) of the ultra-high-performance concrete (UHPC) without rebar and the reinforced concrete (RC) using steel re-bars. This reinforced concrete is mostly used in the concrete bridge decks. A mixture of sand, gravel, cement, water, steel fiber, superplasticizer, and micro silica was used to fabricate UHPC specimens. The extended finite element method as used in the ABAQUS software is applied for considering the mechanical properties of UHPC, RC, and ordinary concrete specimens. To calibrate the ABAQUS, some experimental tests have been carried out in the laboratory to measure the direct tensile strength of UHPC by the compressive-to-tensile load converting (CTLC) device. This device contains a concrete specimen and is mounted on a universal tensile testing apparatus. In the experiments, three types of mixed concrete were used for UHPC specimens. The tensile strength of these specimens ranges from 9.24 to 11.4 MPa, which is relatively high compared with ordinary concrete specimens, which have a tensile strength ranging from 2 to 5 MPa. In the experimental tests, the UHPC specimen of size 150×60×190 mm with a central hole of 75 mm (in diameter)×60 mm (in thickness) was specially made in the laboratory, and its direct tensile strength was measured by the CTLC device. However, the numerical simulation results for the tensile strength and failure mechanism of the UHPC were very close to those measured experimentally. From comparing the numerical and experimental results obtained in this study, it has been concluded that UHPC can be effectively used for bridge decks.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05b
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• pp.21-22
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• 2010

In this research, the purpose is to share fire resistance method to secure 3 hours fire resistance performance which is regulation noticed by Ministry of Land, Transport and Maritime Affairs for 100MPa high strength concrete which is predicted to apply to high rise building and to propose the guideline for confirmation of fire resistance performance of high strength concrete member to which fire resistance method is applied and field application in advance.

• Structural Engineering and Mechanics
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• v.50 no.6
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• pp.709-722
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• 2014

Ultra-High Performance Concrete (UHPC) is an innovative new material that, in comparison to conventional concretes, has high compressive strength and excellent ductility properties achieved through the addition of randomly dispersed short fibers to the concrete mix. This study presents the results of an experimental investigation on the behavior of axially loaded UHPC short circular columns wrapped with Carbon-FRP (CFRP), Glass-FRP (GFRP), and Aramid-FRP (AFRP) sheets. Six plain and 36 different types of FRP-wrapped UHPC columns with a diameter of 100 mm and a length of 200 mm were tested under monotonic axial compression. To predict the ultimate strength of the FRP-wrapped UHPC columns, a simple confinement model is presented and compared with four selected confinement models from the literature that have been developed for low and normal strength concrete columns. The results show that the FRP sheets can significantly enhance the ultimate strength and strain capacity of the UHPC columns. The average greatest increase in the ultimate strength and strain for the CFRP- and GFRP-wrapped UHPC columns was 48% and 128%, respectively, compared to that of their unconfined counterparts. All the selected confinement models overestimated the ultimate strength of the FRP-wrapped UHPC columns.