• Title/Summary/Keyword: Hardened concrete

Search Result 569, Processing Time 0.024 seconds

Effect of the PC, diatomite and zeolite on the performance of concrete composites

  • Kocak, Yilmaz;Savas, Muhsin
    • Computers and Concrete
    • /
    • v.17 no.6
    • /
    • pp.815-829
    • /
    • 2016
  • This study has been carried out to investigate the effect of the surface properties of Portland cement, diatomite and zeolite on the performance of concrete composites. In this context, to describe the materials used in this study and determine the properties of them, chemical, physical, mineralogical, molecular, thermal, and zeta potential analysis have been applied. In the study, reference (Portland cement), 10%-20% diatomite, 10%-20% zeolite, 5+5%-10+10% diatomite and zeolite were substituted for Portland cement, a total of 7 different cements were obtained. Ultrasonic pulse velocity, capillary water absorption and compressive strength tests were performed on the hardened concrete specimens. Hardened concrete tests have been done on seven different types of concrete, for 28, 56 and 90 days. As a result of experiments it has been identified that both the zeolite and diatomite substitution has a positive effect on the performance of concrete.

Proposal of Plane Spacing Factor for Analyzing Air Void System in Concrete (콘크리트 공극 분석을 위한 평면간격계수의 제안)

  • Jeong, Won-Kyong;Choi, Sung-Yong;Kim, Sung-Hwan;Yun, Kyong-Ku
    • Journal of Industrial Technology
    • /
    • v.25 no.A
    • /
    • pp.39-47
    • /
    • 2005
  • Air void systems in hardened concrete has an important influence on concrete durability such as freeze-thaw resistance, water permeability, surface scaling resistance. Linear traverse method and point count method described at ASTM are the routine analysis of the air void system that have been widely used to estimate the spacing factor in hardened concrete. Recently, many concretes often have a spacing factor higher than the generally accepted $200-250{\mu}m$ limit for the usual range of air contents. This study is proposed to estimate the plane spacing factor by calculation of simplicity. The plane spacing factor need two parameters that are air content and numbers of air voids in the hardened concrete. Those obtained from the standard air-void system analysis of the ASTM C 457. The equation is valid for all values of paste-to-air ratio because the estimation of paste content is unnecessary at the using ASTM C 457. The plane spacing factor yields a similar estimate of the standard spacing factor.

  • PDF

Strategies for finding the adequate air void threshold value in computer assisted determination of air void characteristics in hardened concrete

  • Duh, David;Zarnic, Roko;Bokan-Bosiljkov, Violeta
    • Computers and Concrete
    • /
    • v.5 no.2
    • /
    • pp.101-116
    • /
    • 2008
  • The microscopic determination of air void characteristics in hardened concrete, defined in EN 480-11 as the linear-traverse method, is an extremely time-consuming and tedious task. Over past decades, several researchers have proposed relatively expensive mechanical automated systems which could replace the human operator in this procedure. Recently, the appearance of new high-resolution flatbed scanners has made it possible for the procedure to be automated in a fully-computerized and thus cost-effective way. The results of our work indicate the high sensitivity of such image analysis automated systems firstly to the quality of sample surface preparation, secondly to the selection of the air void threshold value, and finally to the selection of the probe system. However, it can be concluded that in case of careful validation and the use of the approach which is proposed in the paper, such automated systems can give very good estimate of the air void system parameters, defined in EN 480-11. The amount of time saved by using such a procedure is immense, and there is also the possibility of using alternative stereological methods to assess other, perhaps also important, characteristics of air void system in hardened concrete.

An Experimental Study on the Application of Lib-lath Form (리브라스 거푸집의 적용을 위한 실험적 연구)

  • Nam, Jung-Min;Park, Moo-Young;Lee, Young-Do;Jung, Sang-Jin
    • Journal of the Korea Institute of Building Construction
    • /
    • v.4 no.4
    • /
    • pp.103-108
    • /
    • 2004
  • In order for concrete as a basic material constituting reinforced concrete structure to meet the required performance, it is necessary to satisfy various requirements in concrete construction. Among them, form work has significant effects not only on the process of molding fresh concrete but also on the quality and performance of hardened concrete. Recently, the decrease and aging of form workers is becoming a great problem in the construction industry and, as a result, it is required to rationalize form works and reduce labor costs for employing form workers. Because form construction methods decide the type of form according to required performance, it is necessary to develop various form construction methods and examine their performance. Thus the present study purposed to expand the scope of application of form construction methods and, for this purpose, investigated the basic characteristics of rib- lath form and presented a system form construction method.

Evaluation on the Performance of Concrete Containing Metakaolin (메타카올린 혼입 콘크리트의 성능 평가)

  • Won, Jong-Pil;Kwon, Youn-Sung;Lee, Chan-Min;Kim, Wan-Yong
    • Proceedings of the Korean Society of Agricultural Engineers Conference
    • /
    • 2002.10a
    • /
    • pp.153-156
    • /
    • 2002
  • The purpose of this research was to evaluate on the properties of fresh and hardened high-performance concrete(HPC) incorporating high-reactivity metakaolin(HRM). Setting time, heat of hydration, compressive strength, resistance to chloride-ion penetration, and repeated freezing and thawing test were carried out in order to investigate the properties of fresh and hardened state concrete. The properties of the HRM concrete were also compared with those of the portland cement concrete and silica fume(SF) concrete. The laboratory test results indicate that HRM material can be used as a supplementary cementitious material to produce high-performance concrete.

  • PDF

Fresh and hardened properties of concrete containing cold bonded aggregates

  • Thomas, Job;B., Harilal
    • Advances in concrete construction
    • /
    • v.2 no.2
    • /
    • pp.77-89
    • /
    • 2014
  • The properties of fresh and hardened concrete made using three types of artificial cold bonded aggregates are determined. The properties, namely, slump, water absorption, compressive strength and splitting tensile strength of concrete containing artificial aggregate are reported. The variables considered are aggregate type and water-to-cement ratio. Three types of cold bonded aggregates are prepared using fly ash and quarry dust. The water-to-cement ratio of 0.35, 0.45, 0.55 and 0.65 is used. The test result indicates that artificial aggregates can be recommended for making the concrete up to a strength grade of 38 MPa. The use of quarry dust in the production of artificial aggregate mitigates environmental concerns on disposal problems of the dust. Hence, the alternate material proposed in this study is a green technology in concrete production.

Influence of the Mixing Factor on the Properties of Concrete Used Artificial Lightweight Aggregates (인공경량골재를 사용한 콘크리트의 물성에 미치는 배합요인의 영향)

  • Shin, Jae-Kyung;Choi, Jin-Man;Jeong, Yong
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2008.11a
    • /
    • pp.73-77
    • /
    • 2008
  • Structural lightweight concrete will reduced total loads of supporting sections and foundations in archtectural and civil structures. So, the lightweight concrete can be used widely for various purpose in the archtectural and civil structures. This paper were examined the influence of the mixing factor on the fresh and hardened properties of lightweight concrete that are used 2types of the differences properties of lightweight aggregates. According to types of lightweight aggregates, the case of synthetic lightweight aggregate are have need higher s/a; 2~4% on mixing proportion. Lightweight concrete was somewhat exhibit lower compressive strength than ordinary concrete. However it was not showed a marked difference. According to types of lightweight aggregates, the case of synthetic the lightweight aggregate are highest performance in fresh and hardened concrete.

  • PDF

A Fundamental Study on the Fluidity and Engineering Properties of High Flowing Concrete According to the Performance of Superplasticizing agents (고성능감수제의 성능에 따른 고유동콘크리트의 유동특성 및 공학적 특성에 관한 기초적 연구)

  • 강희관;김규용;송하영;김무한
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1996.10a
    • /
    • pp.316-320
    • /
    • 1996
  • It is now increasingly recognized that the fluid properties of superplasticized high flowing concrete can be affected by numerous parameters which characterize either the cement, the mineral or chemical admixture, the mix proportion. Particularly performance of superplasticizers used to enhance the workability and obviously plays a key role in the rtheology of fresh and engineering properties of hardened concrete. In this experiment, it is aimed to investigate and compare the each fluidities and engineering properties of high flowing concrete by performance in each 3 kinds of superplasticizers. And there is to aim the considering about fluidity and viscocity, hardened properties of hig flowing concrete.

  • PDF

A Study on the Influnence of the Properties of Concrete on Powder Content and Shape of Crushed Sand (부순모래의 미립분 함유량 및 입형이 콘크리트의 특성에 미치는 영향에 관한 연구)

  • 이진규;윤기원;임종민;이종태;김성식;한천구
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1996.10a
    • /
    • pp.17-23
    • /
    • 1996
  • The objective of this study is to present the reference data about the influence of concrete properties using crushed sand, according to the change of powder content and grain shape. From the test results. We obtained that as powder content is increased, sand aggregate ratio, water content and S.P/C are increased in mixing design of concrete. The more powder content is the less slump and air content loss are decreased in fresh state, but the higher compressive strength and drying shrinkage are increased in hardened concrete state. As grain shape become round, water content is decreased in mixing design of concrete. And also, loss of slump and air content in fresh state, compressive strength in hardened state are increased.

  • PDF

Fresh and Hardened Properties of Structural Lightweight Concrete according to the Physical Properties of Artificial Lightweight Aggregates (인공경량골재의 물리적 특성에 따른 구조용 경량콘크리트의 프레쉬 및 경화성상)

  • Shin, Jae-Kyung;Choi, Jin-Man;Jeong, Yong;Kim, Yang-Bea;Yoon, Sang-Chun;Jee, Nam-Yong
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2008.11a
    • /
    • pp.377-380
    • /
    • 2008
  • Structural lightweight concrete will reduced total loads of supporting sections and foundations in archtectural and civil structures. So, the lightweight concrete can use widely for various purpose in the archtectural and civil structures. However, the performance of lightweight concrete is essentially dependent of properties of used lightweight aggregates. So, in this paper were examined the fresh and hardened properties of lightweight concrete that are used 3types of the differences properties of lightweight aggregates from lower water-ratio to higher water-ratio of concrete mixing regions. Lightweight concrete was somewhat exhibit larger slump loss than ordinary concrete. Also, the development of compressive strength was lower than ordinary concrete, however it was not showed a marked difference. According to types of lightweight aggregates, the case of synthetic lightweight aggregate are highest performance in fresh and hardened concrete, but it is should be to evaluate the structural performance testing as anchoring and bond strength with reinforcing steel bars.

  • PDF