본 논문은 기존 수중 콘크리트 구조물의 강도관리 및 진단기술의 중요성은 날로 증가함에 따라 개발되고 있는 ROV (Remote Control Vehicle)에 탑재될 수 있는 비파괴 검사 장비를 개발하여 콘크리트 내부의 강도측정을 하고자하였다. 수중화된 슈미트해머와 초음파센서를 통하여 수중에 있는 콘크리트 공시체의 반발경도 및 초음파속도를 계측하여 실제 압축강도 값과 비교하였으며 이를 통하여 수중에서의 강도추정식을 도출하였다. 도출된 3가지 식 중에서 반발경도와 초음파속도를 복합적으로 사용하는 복합식이 가장 정확도가 높았으며 이에 따라 실제 수중에서의 콘크리트의 강도를 추정하고자 할 때 활용 가능성도 높아질 것으로 예상된다.

In this study, compressive behavior of form-block-wall was studied through prism test. In the experiment, main variables are the difference in mix design of block and strength of grout concrete. Experiment result showed that the prism strength of form-block-wall increased in proportion to the strength of grout and block. The initial stiffness in load-displacement curve varied corresponding to the difference of block strength in low strength of grout concrete while there was not a difference of it in the case of high strength of grout concrete.

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.

This study investigated the compressive strength of concrete by using ultrasonic pulse velocity method, and proposed the equation able to predict the compressive strength of concrete.

The pupose of this study is to evaluate compressive strength of concrete applying to dynamic modulus of elasticity. Using the method of fundamental transverse and longitudinal resonant frequencies for concrete specimens, elastic modulus of concrete was measured and the relationship between compressive strength and dynamic modulus of elasticity was predicted.

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.

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%.

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, 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

Up to date, the specifications of construction and maintenance for airport pavement are primarily from ICAO (International Civil Aviation Organization), IATA (International Air Transport Association) or FAA (Federal Aviation Administration). In order to consider circumstances such as rainfall characteristics, this study aims to develop pervious concrete for base course of an airport pavement. Strength characteristic of pervious concrete was investigated with respect to different maximum course aggregate size. When 25mm sized aggregate was used, greatest strength was achieved.

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.

Temperature of fresh concrete can be effectively used to predict the strength of concrete being cured and make an informed decision for stripping the molds. A hygrothermograph and thermo-couple sensors that require an extensive wiring have been applied to measure a temperature of concrete at the early stage of the curing process on site. Therefor, this study on the strength prediction using Maturity is mainly focused on, but the study on the concrete mixing blast furnace slag powder is insufficient. The purpose of this study is to investigate the relationships between compressive strength and equivalent age by Maturity function and is to compare and examine the strength prediction of concrete mixing Blast Furnace Slag Power using ACI and Logistic Curve prediction equation.

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

The purpose of this study was to develope the environmentally favorable method of roller compacted soil concrete pavement using industrial waste red mud. Red mud was the major solid waste produced in the process of alumina extraction from bauxite(Bayer process). For recycling purpose, red mud was treated and applied to use as concrete admixtures. To this end, laboratory test such as compressive strength of soil concrete, and field test such as construction characteristics of soil concrete pavement, had been conducted. From the study results, the compressive strength of soil concrete was strongly related to its matrix proportion and compaction energy. The optimum mix proportion was comprised of cement 300 kg/m3, water 110 kg/m3, fine aggregate 600 kg/m3, course aggregate 1400 kg/m3, red mud admixture 50 kg/m3 and compaction energy above 2.86 cm-kgf/cm3. The 7th-day and 28th-day mean compressive strength of soil concrete were 43.8 MPa and 53.3 MPa each under the optimum condition. Pavement application of soil concrete using red mud admixture indicated that the proposed method was simple in case of construction and showed a good surface texture.

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.

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.

최근 구조물이 노후화되면서 기존 구조물과 시공품질을 관리하는 비파괴검사 평가의 요구가 증가되고 있다. 콘크리트 구조물의 압축강도 추정의 중요성이 건설업계에서 또한 점차적으로 증대되고 있는 실정이고, 시공관리와 품질관리에 있어서 중요한 요소이다. 본 연구는 콘크리트의 압축강도를 비교하기 위한 비파괴 검사법 중 슈미트해머 시험과 충격반향기법을 이용하여 수행되었다. 콘크리트 압축강도와 슈미트해머에 의한 반발경도 값과 충격반향기법 실험결과와의 관계를 알아내는데 초점을 두었으며, 콘크리트의 압축강도와 반발경도 값은 밀접한 관계가 있음을 알 수 있었다.