Journal of The Korea Concrete Institute 

About: Journal of The Korea Concrete Institute is an academic journal published by Korea Concrete Institute. The journal publishes majorly in the area(s): Compressive strength & Flexural strength. It has an ISSN identifier of 1229-5515. Over the lifetime, 1392 publications have been published receiving 3527 citations. The journal is also known as: Journal of the Korea Concrete Institute.

The Effect of Steel-Fiber Contents on the Compressive Stress-Strain Relation of Ultra High Performance Cementitious Composites (UHPCC)

Abstract: The effect of steel-fiber contents on the compressive behavior of ultra high performance cementitious composites (UHPCC) was studied to propose a compressive behavior model for UHPCC. The experiments considered fiber contents of 0~5 vol.% and the results indicated that compressive strength and corresponding strain as well as elastic modulus were improved as the fiber contents increased. Compared to the previous study results obtained from concrete with compressive strength of 100MPa or less, the reinforcement effect on strength showed similar tendency, while the effect on the strain and elastic modulus were much less. Strength, strain, and elastic modulus according to the fiber contents were presented as a linear function of fiber reinforcement index (RI). Fiber reinforcement in UHPCC had no influence on the shape of compressive behavioral curve. Considering its effect on compressive strength, strain, and elastic modulus, a compressive stress-strain relation for UHPCC was proposed.

Flexural Behavior of Reinforced Recycled Aggregate Concrete Beams

Abstract: Building Structure & Resources Research Division, Korea Institute of Construction Technology, Goyang 411-712, KoreaABSTRACT These days the amount of demolished concrete waste has been increasing due to reconstruction and redevelopmentof aged buildings. So the use of recycled aggregates is recommended to solve environmental problems. Some investigations havebeen carried out to study the flexural behavior of reinforced concrete beams with recycled aggregates. But these have some lim-itation due to the use of low quality recycled aggregates and small-scale specimens in the laboratory. The purpose of this exper-imental study is to evaluate the flexural behavior of simply supported RC beams subjected to four-point monotonic loading andmade with recycled aggregates. Seven full-scale RC beams were manufactured with different replacement level of recycled aggre-gates. The main parameters of the study are combination of aggregates. From the test results, the flexural behavior of the beamis described in terms of crack patterns and failure modes. And the flexural strength of RC beam with different types of recycledcoarse aggregates and recycled fine aggregates is compared with the provision of KCI code.Keywords: recycled coarse aggregate, recycled fine aggregate, strength properties, replacement level, construction and demolition waste

Bond Characteristics of Ultra High Performance Concrete

Abstract: Ultra high performance concrete (UHPC), is characterized by its high compressive strength and advanced tensile behavior that is much superior to those of conventional concrete. In order to apply this new material in practice, the bond characteristics of UHPC were evaluated in this study. Pull-out tests between UHPC and deformed steel rebar were carried out according to the modified RILEM test method, and were verified by finite element analysis. From the test results showed that UHPC presents 5 to 10 times higher bond strength compared to normal strength concrete, this study suggested remarkably reduced development length and concrete cover comparing to existing specifications. The test results of 700 MPa high strength steel rebar demonstrated the applicability of high strength steel to UHPC. In addition, the transfer length measurements of seven-wire strand in UHPC specimens indicated that the transfer length limit set by the current design code is very conservative for UHPC.

Strength Development of Blended Sodium Alkali-Activated Ground Granulated Blast-Furnace Slag (GGBS) Mortar

Abstract: Strength model for blasted furnace slag mortar blended with sodium was investigated in this study. The main parameters of AAS (alkali activated slag) mortar were dosage of alkali activator, water to binder ratio (W/B), and aggregate to binder ratio (A/B). For evaluating the property related to the dosage of alkali activator, sodium carbonate (Na2CO3) of 4~8% was added to 4% dosage of sodium hydroxide (NaOH). W/B and A/B was varied 0.45~0.60 and 2.05~2.85, respectively. An alkali qual- ity coefficient combining the amounts of main compositions of source materials and sodium oxide (Na2O) in sodium hydroxide and sodium carbonate is proposed to assess the compressive strength of alkali activated mortars. Test results clearly showed that the compressive strength development of alkali-activated mortars were significantly dependent on the proposed alkali quality coef- ficient. Compressive strength development of AAS mortars were also estimated using the formula specified in the previous study, which was calibrated using the collected database. Predictions from the simplified equations showed good agreements with the test

An Experimental Study on the Joints in Ultra High Performance Precast Concrete Segmental Bridges

Abstract: Failures of segmental bridges have been attributed to the inadequate joint connection techniques, which led to corrosion of the post-tensioned tendons connecting the segmental joints. The principal objective of this study is to evaluate the performances of the in-situ cast joint and epoxy applied shear key joints as a function of shear and ultimate strengths. Furthermore, shear behavior and strength of shear key joints in ultra high performance precasted concrete segmental bridges are experimentally evaluated to understand its shear failure behavior. The test parameters of shear key shape and type, load-displacement relations, cracking behavior, concrete strength, and fracture modes are considered in the study. Also, several parameters which influence the mechanical behavior of the shear key joint are analyzed. Based on the study results, the optimal shear key shape and joint type are proposed for the joint design and analysis guidelines.