• Title/Summary/Keyword: high strength cement

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Influence of palm oil fuel ash on behaviour of green high-performance fine-grained cement mortar

  • Sagr, Salem Giuma Ibrahim;Johari, M.A. Megat;Mijarsh, M.J.A.
    • Advances in materials Research
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    • v.11 no.2
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    • pp.121-146
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    • 2022
  • In the recent years, the use of agricultural waste in green cement mortar and concrete production has attracted considerable attention because of potential saving in the large areas of landfills and potential enhancement on the performance of mortar. In this research, microparticles of palm oil fuel ash (POFA) obtained from a multistage thermal and mechanical treatment processes of raw POFA originating from palm oil mill was utilized as a pozzolanic material to produce high-performance cement mortar (HPCM). POFA was used as a partial replacement material to ordinary Portland cement (OPC) at replacement levels of 0, 5, 10, 15, 20, 25, 30, 35, 40% by volume. Sand with particle size smaller than 300 ㎛ was used to enhance the performance of the HPCM. The HPCM mixes were tested for workability, compressive strength, ultrasonic pulse velocity (UPV), porosity and absorption. The results portray that the incorporation of micro POFA in HPCMs led to a slight reduction in the compressive strength. At 40% replacement level, the compressive strength was 87.4 MPa at 28 days which is suitable for many high strength applications. Although adding POFA to the cement mixtures harmed the absorption and porosity, those properties were very low at 3.4% and 11.5% respectively at a 40% POFA replacement ratio and after 28 days of curing. The HPCM mixtures containing POFA exhibited greater increase in strength and UPV as well as greater reduction in absorption and porosity than the control OPC mortar from 7 to 28 days of curing age, as a result of the pozzolanic reaction of POFA. Micro POFA with finely graded sand resulted in a dense and high strength cement mortar due to the pozzolanic reaction and increased packing effect. Therefore, it is demonstrated that the POFA could be used with high replacement ratios as a pozzolanic material to produce HPCM.

Fundamental Study on High Strength and High Durability Cement Concrete Pavement: Part II Strength and Durability Evaluations (시멘트콘크리트 포장의 고강도 고내구성을 위한 기초 연구 : Part II 최적배합콘크리트의 강도 및 내구특성 분석)

  • Yun, Kyong-Ku;Park, Cheol-Woo;Hong, Seung-Ho
    • International Journal of Highway Engineering
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    • v.11 no.3
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    • pp.51-60
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    • 2009
  • This study investigates the fresh state characteristics, strength, chloride ion penetration resistance and freeze-thaw resistance of the suggested high strength-high durability cement concrete pavement. The required workability and air content could be achieved by using an appropriate admixtures. However its dosage should be carefully determined through field trial batches. Compressive strength increased with the increased cement content and, in particular, high cement volume concrete continuously developed strength up to 90 days. No clear relationship, however, existed between flexural strength and cement content. Chloride penetration resistance seemed as a function of curing age rather than the cement content. Freeze-thaw resistance test was conducted using two different coolants, tap water and 4% NaCl solution. When the tap water was used no severe damage was observed up to 300 cycles regardless the air content. Under 4% NaCl solution, specimens of 326kg/$m^3$ cement content showed severe damage with surface scaling. Based on the experimental investigations herein, it is highly recommended that the cement content be greater than 400kg/$m^3$ for strength-high durability cement concrete pavement structures.

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An Experimental Study on the Engineering Properties of High Strength Flowing Concrete Using Flyash and Silicafume (Part I. Workability of Fresh Concrete) (플라이애시 및 실리카흄을 사용한 고강도유동화콘크리트의 공학적 특성에 관한 실험적 연구 (제1보, 아직 굳지않은 콘크리트의 시공성 검토))

  • 김진만;이상수;김규용;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 1994.10a
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    • pp.161-166
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    • 1994
  • Production of high strength concrete requires a low water-cement ratio and this leads to the high cement content. Mineral admixture like fly ash(FA) is often cheaper than ordinary portland cement(OPC) and this factor in combination with possible improvement in workability and moderation of the heat evolution of the cement-rich mixes tends to encourage its use. The other mineral admixture that its use has been widly advocated is silica fume that increases compressive strength due to its pozzolanic reaction. The objective of this study is to assess the contribution of mineral admixtures(FA, SF) to the workability and the strength of concrete with low water-binder ratios. In this experimental study that investigates and analyzes the properties of fresh concrete, it is presented that using admixtures like flysh and silica fume as binding material increases properties of high strength flowing concrete having very low water cementitious ratios of 0.25 and 0.30.

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An Experimental Study on the Engineering Properties of High Strength Flowing Concrete Using Flyash and Silicafume (Part 2. Engineering Properties of Hardened concrete) (플라이애시 및 실리카흄을 사용한 고강도유동화 콘크리트의 공학적 특성에 관한 실 험적 연구 (제 2보. 경화콘크리트의 공학적 특성 검토))

  • 김진만;이상수;김규용;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.04a
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    • pp.84-87
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    • 1995
  • Production of high strength concrete requires a low water-cement ratio and this leads to the high cement content. Mineral admixture like fly ash(FA) is often cheaper than ordinary portland cement(OPC) and this factor in combination with possible improvement in workability and moderation of the heat evolution of the cement-rich mixes tends to encourage its use. The other mineral admisture that its use has been widly advocated is silica fume that increases compressive strength due to its pozzolanic reaction. The objective of this study is to assess the contribution of mineral admixtures(FA, SF) to the workability and the strength of concrete with low water-binder ratios. In this experimental study that investigates and analyzes the properties of fresh concrete. it is presented that using admixtures like flyash and silica fume as binding material increases properties of high strength flowing concrete having very low water cementitious ratios of 0.25 and 0.30.

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An Experimental Study on the Mechanical Properties of High Sulphated Cement Concrete with Fly-Ash (고황산염시멘트와 플라이애쉬를 사용한 고강도콘크리트의 역학적 특성에 관한 실험적 연구)

  • 박승범;임창덕;최수홍
    • Proceedings of the Korea Concrete Institute Conference
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    • 1994.04a
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    • pp.175-180
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    • 1994
  • The purpose of this experimental study is to improve the workability and durability in high sulphated cement concrete with fly-ash. As a results, we can make high strength concrete by using only high sulphated cement but try to improve the workability and degree of strength by adding 10% fly-ash but the effect beyond my expectation to improve the workability and degree of strength does not show, and the improvable effect except the drying shrinkage of durability dose not show, either. So we must give attention to using fly-ash.

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A Study on Early Strength Estimation of High-strength Concrete Using Non-sintering Cement (NSC) (비소성시멘트를 사용한 고강도 콘크리트의 조기강도 추정 연구)

  • Kim, Han-Sik;Lim, Sang-Jun;Kang, In-Seuk;Park, Moo-Young;Mun, Kyung-Ju;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.609-612
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    • 2006
  • The quality of the concrete compression strength can be determined after the passage of 28 days, but if any defect is found the quality of concrete after that length of time, there can be serious problems in dismantling and repair. Thus, in response to the use of concrete using non sintering cement (NSC), the present study purposed to propose a method of managing the strength of high strength concrete using NSC in comparison with high strength concrete using ordinary Portland cement (OPC) through early strength estimation using microwave, which enables the quick estimation of the strength of high strength concrete using NSC.

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A Study On the Chemical shrinkage and Autogenous Shrinkage of High strength Concrete (고강도 콘크리트의 수화수축과 자기수축의 실험연구)

  • Heo, Woo-Young;Kim, Wha-Jung
    • Journal of the Korea Institute of Building Construction
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    • v.4 no.2
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    • pp.81-88
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    • 2004
  • The purpose of this study is to investigate the chemical shrinkage and autogenous shrinkage of high strength cement paste and silica fume and fly ash and sand to cement ratio by the method of volumetric tests, and also investigate the autogenous shrinkage of high measurement method, and compare the results of volumetric test and linear length measurement test. A series of cement paste which have W/C ratio of 25%, 35%, 45% respectively were planed to study the effect of the W/C ratio to the shrinkages, and a series of cement paste which were replaced the cement by the silica fume and fly ash with 5%, 10%, 15% as the mass of cement respectively were planed to investigate the effects of poazolana to the shrinkages. A series of mortar which have a C/S ratio of 1:1, 1:1.5, 1:2 respectively were planed to investigate the shrinkage resistant effect of aggregate.

Effect of Microstructure on the Properties of High Strength Hardened Cement Paste(I) (고강도 시멘트 경화체의 특성에 미치는 미세구조의 영향(I))

  • 김정환;최상흘;한기성
    • Journal of the Korean Ceramic Society
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    • v.27 no.7
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    • pp.861-868
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    • 1990
  • Investigation for the preparation of high strength hardened cement paste using ordinary portland cement, hydroxypropyl methyl cellulose(HPMC) with SiC powder was carried out. The cement paste was mixed with 0.1 of water cement ratio by twin roll mill and cured 60 days in humidity chamber. The hydration degree of cement paste cured with W/C=0.1 in 60 days was about 30% and most pores in the paste were found to be existed as gel pores of diameter less than 0.01㎛. The maximum flexural strength of hardened cement paste was about 960kg/㎠. When the SiC powder was added to the paste, the flexural strength was 1000∼1100kg/㎠ and the Young's modulus was 8∼9×105kg/㎠.

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Exploring the Flexural Bond Strength of Polymer-Cement Composition in Crack Repair Applications (균열 보수용 폴리머 시멘트 복합체의 휨접착강도에 관한 연구)

  • Jo, Young-Kug
    • Journal of the Korea Institute of Building Construction
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    • v.24 no.1
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    • pp.23-34
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    • 2024
  • This research aims to assess the flexural bonding efficacy of polymer-cement composites(PCCs) in mending cracks within reinforced concrete(RC) structures. The study involved infilling PCCs into cement mortar cracks of varying dimensions, followed by evaluations of enhancements in flexural adhesion and strength. The findings indicate that the flexural bond performance of PCCs in crack repair is influenced by the cement type, polymer dispersion, and the polymer-to-binder ratio. Specifically, the use of ultra-high early strength cement combined with silica fume resulted in an up to 19.0% improvement in flexural bond strength compared to the application of ordinary Portland cement with silica fume. It was observed that the augmentation in flexural strength of cement mortar filled with PCCs was significantly more dependent on the depth of the crack rather than the width. Furthermore, PCCs not only acted as repair agents but also as reinforcement materials, enhancing the flexural strength to a certain extent. Consequently, this study concludes that PCCs formulated with ultra-high early strength cement, various polymer dispersions, silica fume, and a high polymer-to-binder ratio ranging from 60% to 80% are highly effective as maintenance materials for crack filling in practical settings.

Development of high performance shotcrete for permanent shotcrete tunnel linings (Application of high-early strength cement with alkali-free accelerator in spring water condition) (영구 숏크리트 터널 라이닝 구축을 위한 고성능 숏크리트 개발 (용수부에서의 조강시멘트와 alkali-free급결제 적용 검토))

  • Park, Hae Geun;Lee, Myeong Sub;Kim, Jea Kwon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.1
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    • pp.23-31
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    • 2003
  • Since the mid of 1990, permanent shotcrete tunnel linings such as Single-shell and NMT have been constructed in many countries for reducing the construction time and lowing construction costs instead of conventional in-situ concrete linings. Among essential technologies for successful application of permanent shotcrete linings, high performance shotcrete having high strength, high durability and better pumpability has to be developed in advance as an integral component. This paper presents the idea and first experimental attempts to increase early strength and bond strength of wet-mixed Steel Fiber Reinforced Shotcrete (SFRS) in spring water condition. In order to increase early behavior of SFRS, a new approach using high-early strength cement with alkali-free liquid accelerator has been investigated. From the test results, wet-mix SFRS with high-early strength cement and alkali-free accelerator exhibited excellent early compressive strength improvement compared to the ordinary portland cement and good bond strength even under spring water condition.

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