• International Journal of Concrete Structures and Materials
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• v.18 no.2E
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• pp.117-124
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• 2006

Porous concrete has been used recently for the purpose of decreasing the load on the earth environment. It consists solely of cement, water and coarse aggregate of uni form size. Its fundamental properties are considerably affected by the physical properties of aggregate because the aggregate is the main material for the most part in its mix proportion. Because of this reason, this study carried out an investigation of the influence of the size and type of aggregate on the fundamental properties of porous concrete. It is shown that the fundamental properties of porous concrete was seldom affected by the size of aggregate except for the case of using $2.5{\sim}5mm$ aggregate but varied significantly by the type of aggregate. In particular, the compressive strength of porous concrete using $2.5{\sim}5mm$ aggregate was much higher than that using other aggregate, and its void ratio and coefficient of permeability was lower. Moreover, the capacity to maintain the permeability of porous concrete was found to vary by the size and type of aggregate. Of particular notice was that it decreased greatly when $2.5{\sim}5mm$ aggregate was used. Unlike ordinary concrete, porous concrete exhibited very high dynamic modulus of elasticity at early age and continued to increase but slowly afterwards.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.99-100
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• 2012

Aggregate thermal properties and cooling methods are most important to evaluate the residual mechanical properties of concrete. In this study, we evaluate the residual mechanical properties of concrete according to the aggregate type and cooling method. We use the normal weight aggregate and light weight aggregate which have different thermal properties. After heating to the target temperature, we evaluate the mechanical properties according to the slow and fast cooling condition. As a result, normal weight aggregate concrete has higher effectiveness of cooling conditions than light weight aggregate concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.239-242
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• 2002

This study is intended to investigate the relationship between rebound value of P type schmidt hammer and the compressive strength with various aggregates, and a series of experiments about early strength quality control by P type schmidt hammer was performed. According to the results, the compressive strength of concrete using basalt and limestone aggregate is higher by 3% and lower by 4% than that of concrete using granite aggregate respectively. Concrete using basalt and lime stone aggregate show high rebound value in vertical strike. Estimation of the compressive strength does not show differences in horizontal strike, but the compressive strength is estimated high in order of granite, basalt and limestone aggregate in vertical strike. A good correlation between the rebound value of schmidt hammer and the compressive strength is confirmed regardless of aggregate types, so it could be possible to control the quality of concrete by P type schmidt hammer test when basalt and limestone aggregates are used at the same time.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.90-100
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• 1995

This study was performed to develop the lightweight concrete using synthetic lightweight aggregate and natural coarse aggregate. Mixing ratios were three types, the first type was mixed cement and synthetic lightweight fine aggregate (Type CP), the second type was mixed cement, synthetic lightweight fine aggregate and synthetic lightweight coarse aggregate (Type CPE), the third type was mixed cement, synthetic lightweight fine aggregate and natural coarse aggregate (Type CPN). The results of this study are summarized as follows ; 1. The W/C of each mixing ratio was increased with increase of the amount of cement used, and it was shown higher in order of Type CP, CPN, CPE. 2. The unit weight of Type CP, CPE and CPN was 1.473~1.647g/cm$^3$, 1.467~1.622g/cm$^3$ and 1.658~1 .838g/cm$^3$, respectively. And the absorption ratio was approximately 20%, which was higher than that of the normal cement concrete. 3. The compressive strength of Type CP was shown 178 ~249kg/cm2, Type CPE was shown 149~241kg/cm$^2$ and Type CPN was shown 196~297kg/cm$^2$, respectively. Each strength ratio was smaller than that of the normal cement concrete. 4. The pulse velocity of Type CP, CPE and CPN was 2, 688~3, 240m/sec, 2, 981~3, 324m/sec and 2, 989 ~ 3, 545m/sec, respectively. And it was increased with increase of strength and unit weight. 5. The length change ratio at 28 days was in the range of 0.057~0.077%, and earlier length change ratio was higher than that of the later.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.111-112
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• 2022

Lightweight aggregate is a porous material that has a lower density than natural aggregate and is a lightweight construction material. Lightweight Aggregate has a suitable purpose because it is effective in reducing the heavy unit mass in high-rise buildings. However, since lightweight aggregate has weak strength and high water absorption compared to natural aggregate, it is difficult to control the quality of concrete. Although lightweight aggregate has disadvantages such as high water absorption, it is expected that the demand for lightweight aggregate concrete will continue to use in the future because the advantage of being able to reduce the weight of concrete is greater. In this study, we conducted an experimantal study on the compressive strength property of cement matrix according to the type of lightweight aggregate.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.1
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• pp.73-80
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• 1995

This study was carried out to investigate the engineering properties of no-fines con- crete, consisting only of coarse aggregate, cement and water. The used coarse aggregates were two, one is natural coarse aggregate grading 4.75~ lOmm, the other is synthetic lightweight coarse aggregate grading 3~8mm. The results of this study are summarized as follows; 1. The W/C ratio of each type was increased with increase of additional amount of coarse aggregate. 2. The unit weight of used ndtural coarse aggregate was shown 1.762~2.184g/cm$^3$, and synthetic lightweight coarse aggregate was shown 0.756 ~ 1 .348g/cm$^3$. 3. The ahsorption rate of used natural coarse aggregate was shown 8.4 ~ 9.4 %, and synthetic lightweight coarse aggregate was shown 17.0~42.4%. 4. The compressive, tensile and hending strength was decreased with increase of coarse aggregate, respectively. The compressive strength of natural coarse aggregate 1:3 was shown 309kg/cm$^2$. 5. The ultrasonic pulse velocity and dynamic medulus of elasticity of each type was de- creased with increase coarse aggregate, respectively. Also, the decreasing rate of the natural aggregate was larger than that of the synthetic lightweight coarse ag- gregate.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.153-156
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• 2006

This study investigated influence of kind of fine aggregate on fundamental properties of concrete. For the properties of fluidity with various type of fine aggregate, lime stone crushed fine aggregate(Ls) exhibited favorable result, due to grain shape and particle distribution, and next was granite crushed fine aggregate(Gs), natural fine aggregate(Ns). Ns had the highest value of air content while Ls had the lowest, due to the effective filling performance by continuos particle distribution. Ls, Ns, Gs in an order had higher bleeding capacity and faster setting time. However, compressive and tensile strength value exhibited similar tendency, regardless of aggregate type.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.63-64
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• 2012

In case of concrete, it should be deformed by many factors, such as explosive spalling, thermal strain and creep at high temperature. Structural fire design has been proposed to predict fire damage as national standard. It is general safer to use values obtained from tests of unstressed residual test in stead of stressed test. But most of thermal properties on concrete were conducted with normal aggregate. In this study, it evaluated mechanical properties of concrete with aggregate type and loading condition. we use normal and light aggregate to have different thermal properties. Also, we test mechanical properties to use Ø100×200 mm cylinder specimen according to target temperature and 0%, 20%, 40% loading.

• Computers and Concrete
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• v.2 no.3
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• pp.239-248
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• 2005

The article presents the results of examination of the fractal dimension D of concrete specimen fracture surfaces obtained in fracture toughness tests. The concretes were made from three different types of coarse aggregate: gravel, dolomite and basalt aggregate. Ordinary concretes (C40) and high-performance concretes (HPC) were subjected to testing after 7, 14, 28 and 90 days of curing, respectively. In fracture toughness and compressive tests, different behaviours of concretes were found, depending on the type of aggregate and class of concrete (C40, HPC). A significant increase in the strength parameters tested occurred also after a period of 28 days (up to the $90^{th}$ day of curing) and was particularly large for concretes C40. Fractal examinations performed on fracture replicas showed that the fractal dimension D was diverse, depending on the coarse aggregate type and concrete class being, however, statistically constant after 7 and 14 days for respective concretes during curing. The fractal dimension D was the greater, the worse strength properties were possessed by the concrete. A cross-grain crack propagation occurred in that case, due to weak cohesion forces at the coarse aggregate/mortar interface. A similar effect was observed for C40 and HPC made from the same aggregate. A greater dimension D was exhibited by concretes C40, in which case the fracture was easier to form compared with high-performance concretes, where, as a result of high aggregate/mortar cohesion forces, the crack propagation was of inter-granular type, and the resulted fracture was flatter.

• Steel and Composite Structures
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• v.17 no.6
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• pp.929-949
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• 2014

Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concrete-filled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.