It will use the Schmidt hammer law, the Ultrasonic waves velocity law and the composition law in the concrete Korean mandolin lump examination law from the research which it sees consequently and proposal of the usual concrete and existing regarding the high-in-tensity concrete the comparison which will be cool it will analyze and compared to accurately the burglar presumption which is the possibility of buying the compressive strength of the concrete it will be cool and it proposes.

In this study, compressive capacity of a new form-block-wall (FBW) was studied through both the prism test and compressive strength test for single form-block. In the experiment, main variables are the difference in mix design of block and in strength of grout concrete. The result of prism test showed that the compressive strength of FBW was largely influenced by the strength of grout concrete while it was not influenced by the block‘s mix design difference.

Concrete structures known that relatively safe for the fire, but the fire damage at different depending on the materials used will be affected, depending on the strength of the concrete damage situation appears different. In this study compared to compressive strength properties acooding to different type of concrete strength fire damege through about concrete structure is utilized as a basis for maintenance.

Based on the study of compressive strength due to SPC(sulfur polymer cement) content variation in the sulfur polymer concrete , it was found that the SPC content was required more than 16% to get over 50 MPa compressive strength and increasing ratio of the strength was greatest at SPC 14%.

This paper reviewed on the minimum strength of concrete in cold climates from the viewpoint of durability. The results show that the minimum strength to prevent early frost damage recommend to 21 MPa.

In this study, to improve the early-age compressive strength of concrete, the powder of rapid setting additives crushed by treatment with functional grinding aid, the power-typed rapid setting cement clinker by sintering industrial waste and byproducts containing a large amount of CaO-SiO2-Al2O3 was developed. And, after adding smart BFS powder to powder of rapid setting additives, the strength tests were performed

In this study, KS F 2405 was used to investigated the compressive strength of property of high performance concrete (HPC) using the fly ash and silica fume. The experiments were carried out silica fume-binder ratio from 5% (SF5) and fly ash 25%+silica fume 5% (FA25SF5). The compressive strength of HPC determined on 7days and 28days.

In this study, we investigated the physical properties and thermal behaviors of specimens that applied different mixing ratios of foaming agent to evaluate the possibility of use in the structural elements. We proposed the estimating equation for compressive strength of each mix having different ratio of foaming agent. We also confirmed that the density of cement matrix is decreased as the mixing amount of foaming agent increase up to 0.6% of foaming agent mixing ratio which was observed by SEM. Based on porosity and compressive strength of control mortar without foaming agent, we built the estimating equations of compressive strength for mortars with foaming agent

This paper is to investigate experimentally the effect of waste cooking oil on compressive strength and chloride penetration resistance of high volume fly ash and blast furnace slag concrete. According to results, the incorporation of waste cooking oil resulted in an improvement of penetration resistance of chloride.

In this study, one of nondestructive evaluation (NDE)　techniques for the effective maintenance of underwater concrete structures are investigated: Ultrasonic Pulse Velocity Method and Rebound hardness Test. Currently, lots of ROV(Romotely Operated Vehicle) Systems to inspection Underwater Concrete Structures are being considered.

In this study, I tried to derive the expression intensity estimation through analyzing the correlation between wave velocity and compressive strength of high-strength concrete and normal-strength one, using ultrasonic pulse velocity which is one of the non-destructive tests which do not damage the structure. By producing a material age strength and body separate experiment which is applied to the ultrasonic pulse velocity, we have derived the estimating compressive strength such as a formula strength of normal-strength concrete : Fc=0.0841vp3.6018, R2=0.82 high strength concrete : Fc=0.0008vp6.9287, R2=0.88. As a result of this verification experiment, the estimated error rate of the compressive strength of normal strength concrete is 16.32%, in the case of high-strength concrete is now 7.58 percent.

콘크리트의 강도는 시간에 따라 증가하며, 많은 연구에서 시간에 대한 회귀 분석식을 사용하고 있다. 본 연구는 수화물량을 수화도 및 공극률의 함수로 가정하였으며, 재령의 증가에 따라 감소하는 공극률을 이용하여 고성능 콘크리트의 압축강도 모델링을 수행하였다. 본 연구에서는 기존의 시간에 대한 회귀분석없이 공극률의 감소만을 이용하여 압축강도를 예측하였다. 총 21개의 고성능 콘크리트 배합에 대해 초기재령 콘크리트의 거동 해석프로그램인 DUCOM을 이용하여 각각의 공극률을 도출하였으며, 강도 모델링을 수행하였다. OPC 콘크리트에 대해서 수화도, 단위시멘트량, 공극률의 함수로 강도 예측식을 제안하였으며, GGBFS 및 FA를 혼입한 콘크리트에 대해서는 장기강도 영향을 구현하기 위해 공극률을 고려한 장기강도변수를 도입하였다. 기존의 실험결과와의 비교를 통하여 제안된 강도예측식의 타당성을 입증하였다.

As Concrete is construction materials which is unevenly mixed with cement, aggregate and water, compressive strength and modulus of elasticity is an important factor to seize movement of structures. The purpose of this study is to investigate a correlation compressive strength and modulus of elasticity according to the size of structures, and also to analyze and compare to prediction equation of many countries.

In this study, specimens were produced to reach design standard strengths 40, 50 and 60MPa on age 28 days to evaluate the usability of high strength recycled aggregate concrete and the applicability of compressive strength by Impact Echo method and numerical analysis, and after 0, 30, 50 and 100% recycled coarse aggregates were substituted and mixed into each combination, totally 12 combinations were set. And, through compressive strength test, Impact Echo method, shock reverberation technique and numerical analysis on 1, 3, 7 and 28 days of age

이 연구에서는 콘크리트 압축강도에 따른 고강도 나선철근의 횡구속 성능을 평가하고자 하였다. 총 24체의 실린더형 콘크리트 실험체(150×300mm)를 제작하고 단조 압축하중 실험을 수행하였다. 주요 실험변수는 나선철근의 항복강도와 콘크리트 압축강도로 계획하였다. 나선철근의 항복강도에 따른 횡구속 효과를 효과적으로 평가하기 위하여 나선철근의 외경을 실험체 직경과 동일하게 계획하였다. 실험결과, 나선철근의 횡구속 성능은 나선철근의 항복강도가 증가할수록 그리고 콘크리트 압축강도가 낮아질수록 증가하였다. 또한 기존 해석모델을 이용하여 실험체의 응력-축변형률 관계를 예측한 결과, 해석결과는 나선철근의 항복강도와 콘크리트 압축강도가 증가할수록 정확성이 떨어지는 것으로 확인되었다.

The objective of this study is to investigted the mechanical properties used cement mix-materials, blast furnace slag. Experimental variables of this study are replacement ratio of blast furnace slag.

It was evaluated penetration depth and spalling resist thickness by compressive strength. As a result, it was found that the more compressive strength is increased, the penetration depth is suppressed. And the result of this study are similar to modified NDRC formula and US ACE formula.

메타카올린은 고령토나 카올린으로 알려진 카올린 광물의 풍화물로, 도자기 산업에 주로 사용되는 원료로, 일반적으로 메타카올린의 입자 크기는 시멘트보다는 작지만, 마이크로 실리카퓸보다는 크다. 본 연구에서는 콘크리트용 혼화재로 메타카올린을사용한 콘크리트의 압축강도와 염소이온 투과저항 특성에 관한 영향에 관해 조사하였다. 메타카올린과 실리카퓸의 혼입률이 압축강도와 염소이온 투과저항에 주는 영향을 비교하기 위해 물-결합재비를 30%로 고정하고 각각 0, 5, 10, 15, 20%인 배합수준을 설정하여 비교하였다. 연구결과 메타카올린을 혼입한 콘크리트는 실리카퓸을 혼입한 콘크리트와 유사한 강도특성을 보였지만, 염소이온 투과저항성은 다소 불리한 것으로 나타났다. 따라서, 강도와 염소이온 투과저항 성능을 동시에 만족하기 위한메타카올린의 혼입률은 10% 정도인 것으로 나타났다.