• Title/Summary/Keyword: Fresh State Properties

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Consideration on Usability of Modified Sulfur of Low-Slump Concrete (저슬럼프 콘크리트의 개질유황 사용성에 대한 검토)

  • Shin, Hyo-Chul;Kim, Gyu-Yong;Kim, Jung-Hyun;Kim, Jin-Man
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.11a
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    • pp.109-110
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    • 2015
  • In this study, fresh state properties and mechanical properties of low slump concrete which is applied to road pavement have been evaluated by mixing modified sulfur. As results, influence of mixing modified sulfur on the workability was low. Also, compressive strength, and flexural strength tend to decrese with increasing addition rate of modified sulfur. However compressive strength, and flexural strength of modified sulfur concrete were equivalent with that of plain concrete.

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A Study on the Waterproof Properties of Cement Mortar with the Addition Rate of the Inorganic Admixture and Zinc Stearate (무기질 혼화재 및 금속비누의 혼입률 변화에 따른 시멘트 모르터의 방수 특성에 관한 연구)

  • Choi, Hoon;Jiang, Yi-Long;Han, Min-Cheol;Ryu, Hyun-Ki;Han, Cheon-Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10c
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    • pp.139-144
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    • 1998
  • This study is intended to devolop the self waterproof agents for high performance concrete by analyzing the properties of fresh and hardened mortar with various addition ratios of the inorganic admixture and zinc stearate. As the results of the test, the flow and air content increase with the addition of expansive additives. When the replacement rate of silica fume increases, the flow decreases for the increased viscidity. And the flow and sir content decrease with the addition of zinc stearate. At hardened state, the compressive strength, tensile strength and flexual strength decrease with the addition of expansive additives and zinc stearate. With the increase of silica fume's replacement, they show a little decrease at early age and then increase gradually. Also, absorption and permeability show a steep decrease when zinc stearate is added, and a slack decrease with the replacement of silica fume.

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Properities of Freshly Mixed Concrete Using Recycled Coarse Aggregates and Steel Fiber (강섬유를 혼입한 굳지 않은 재생 콘크리트의 특성에 관한 연구)

  • 구봉근;김창운;김태봉;박재성
    • Journal of the Korea Concrete Institute
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    • v.12 no.5
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    • pp.93-99
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    • 2000
  • The physical properties of freshly mixed steel fiber reinforced recycled concrete(SFRRC) were_investigated. Physical state and quality of fresh concrete were monitored batch by batch. the properties of freshly mixed SFRRC were determined in terms of slump, air content, superplasticizer, and bleeding ratio. Concrete mixtures were produced for three kinds of aggregate proportions. So, the experimental variables are various aggregate proportions, steel fiber contents(0, 0.5, 1.0, 1.5%) and steel length(30, 50, 60mm). From experimental results, optimum s/a by various experimental variables, variations of the slump by the air contents, and optimum superplasticizer to decrease unit water were presented.

Experimental Study on Engineering Properties of Concrete Using Fluosilicates Based Composite (규불화염계 복합 조성물을 혼입한 콘크리트의 공학적 특성에 관한 실험적 연구)

  • Yang Il-Seung;Yun Hyun-Do;Kim Do-Su;Khil Bae-Su;Han Seung-Gu
    • Journal of the Korea Concrete Institute
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    • v.17 no.5 s.89
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    • pp.769-774
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    • 2005
  • Fluosilicic acid(H2SiF6) is recovered as an aqueous solution which absorbs $SiF_4$ produced from the manufacturing of industrial-graded H3PO4 or HF. Generally, fluosilicates are the salts produced by the reaction of H2SiF6 and metal salts. Addition of fluosilicates to cement endows odd properties through unique chemical reaction with the fresh and hardened cement. This study was performed to know mechanical properties and watertightness using fluosilicates based composite made from fluosilicates and other compounds. Mix proportions for experiments were modulated at 0.45 of water to cement ratio and $0.0-2.0\%$ of adding ratio of fluosilicates based composite. Evaluation for mechanical properties of concrete was conducted to know fresh state of concrete, hardening state of concrete, and watertightness. Evaluation for watertightness of concrete was carried out permeability, absorption test and porosity analysis. In addition. Scanning Electron Microscopy(SEM) and Energy Dispersive X-Ray(EDX) used for investigating micro-structure and atomic component distributed in hardened concrete. It is ascertained that characteristics of mechanical properties and watertightness was more improved than non-added because of packing role of fluosilicates based composite and pozzolanic reaction of soluble $SiO_2$. Also, concrete added fluosilicates based composite had a tendency to delay setting time and only $0.5\%$ addition of fluosilicates based composite delayed 150 minutes compared with non-added.

Mechanical properties of sustainable green self-compacting concrete incorporating recycled waste PET: A state-of-the-art review

  • Shireen T. Saadullah;James H. Haido;Yaman S.S. Al-Kamaki
    • Advances in concrete construction
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    • v.16 no.1
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    • pp.35-57
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    • 2023
  • Majority of the plastic produced each year is being disposed in land after single-use, which becomes waste and takes up a lot of storage space. Therefore, there is an urgent need to find alternative solutions instead of disposal. Recycling and reusing the PET plastic waste as aggregate replacement and fiber in concrete production can be one of the eco- friendly methods as there is a great demand for concrete around the world, especially in developing countries by raising human awareness of the environment, the economy, and Carbon dioxide (CO2) emissions. Self-compacting concrete (SCC) is a key development in concrete technology that offers a number of attractive features over traditional concrete applications. Recently, in order to improve its durability and prevent such plastics from directly contacting the environment, various kinds of plastics have been added. This review article summarizes the latest evident on the performance of SCC containing recycled PET as eco-friendly aggregates and fiber. Moreover, it highlights the influence of substitution content, shape, length, and size on the fresh and properties of SCC incorporating PET plastic. Based on the findings of the articles that were reviewed for this study, it is observed that SCC made of PET plastic (PETSCC) can be employed in construction era owing to its acceptable mechanical and fresh properties. On the other hand, it is concluded that owing to the lightweight nature of plastic aggregate, Reusing PET waste in the construction application is an effective approach to reduces the earthquake risk of a building.

Influence of Foaming Agents on the Properties of Foamed Concretes Having Various Densities

  • Kim, Jin-Man;Jeong, Ji-Yong
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.1
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    • pp.22-30
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    • 2012
  • Four types of foaming agents, including Alcohol Ethoxy Sulfate (AES), Alpha Olefin Sulfonate (AOS), Vegetable Soap (VS), and Fe-Protein (FP), are widely used in the construction field. These have different surface tensions and viscosities in water of the same concentration, affecting the flow speed of liquid, size and distribution of foam, and foam stability. However, there is a lack of data regarding the properties of foam concrete using various foam agents. The purpose of this study is to investigate influence of foaming agents on the properties of foamed concretes with various densities. We find that the foaming agent type has little effect on the density, compressive strength, and thermal conductivity of foam concrete, but considerably affects the unit weight of foam, flow and flexural strength of foamed concrete. While almost all properties of foam concrete are affected by density in fresh or hardened state, the potential energy changed by slurry density and the viscosity of foam are dominant factors in the flowability of foam slurry.

Preparation of Waxy Barley Cake and Its Quality Characteristics (찰보리를 이용한 인절미 제조와 품질 특성)

  • 윤계순;고하영
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.27 no.5
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    • pp.890-896
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    • 1998
  • In order to increase the use of waxy barley, cakes were made and the textural and sensory properties were investigated. The moisture content of cakes made out of waxy barley grain and flour were 51.0 and 52.1%, respectively. L values in color of the waxy barley cakes tended to decrease during 3 day storage at 15$^{\circ}C$. Textural analysis showed that there were no differences among two waxy barley and waxy rice cakes in hardness at fresh state. But after 3 day storage at 15$^{\circ}C$, the hardness of the waxy barley cake was lower than that of waxy rice cake. These results implied that the degree of retrogradation of waxy barley cake might be low due to its high dietary fiber content. The hardness and adhesiveness of the waxy barley cake thawed after 15 day freezing were not significantly different from those of the fresh cake. In sensory evaluation, the overall preference of waxy barley cake was lower than that of waxy rice, but the sensory score of the cake made of waxy baley flour was above 4 point in the 5 point scale, showing a patency of waxy barley for the cakes.

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Rheology Control of Cement Paste for Applying ECC Produced with Slag Particles to Self-Consolidating and Shotcreting Process (고로슬래그 미분말이 혼입된 자기충전 및 숏크리트용 ECC의 개발을 위한 시멘트풀 레올로지 제어)

  • Park, Seung-Bum;Kim, Jeong-Su;Kim, Yun-Yong
    • Journal of the Korea Concrete Institute
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    • v.20 no.1
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    • pp.67-75
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    • 2008
  • An engineered cementitious composite produced with slag particles (Slag-ECC) had been developed based on micromechanical principle. Base grain ingredients were properly selected, and then the mixture proportion was optimized to be capable of achieving robust tensile ductility in the hardened state. The rheological design is performed in the present study by optimizing the amount of admixtures suitable for self-consolidating casting and shotcreting process in the fresh state. A special focus is placed on the rheological control which is directly applicable to the construction in field, using prepackaged product with all pulverized ingredients. To control the rheological properties of the composite, which possesses different fluid properties to facilitate two types of processing (i.e., self-consolidating and shotcreting processing), the viscosity change of the cement paste suspensions over time was initially investigated, and then the proper dosage of the admixtures in the cement paste was selected. The two types of mixture proportion were then optimized by self-consolidating & shotcreting tests. A series of self-consolidating and shotcreting tests demonstrated excellent self-consolidation property and sprayability of the Slag-ECC. The rheological properties altered through this approach were revealed to be effective in obtaining Slag-ECC hardened properties, represented by pseudo strain-hardening behavior in uniaxial tension, allowing the readily achievement of the desired function of the fresh Slag-ECC. These ductile composites with self-consolidating and shotcreting processing can be broadly utilized for a variety of applications, e.g., in strengthening seismic resistant structures with congested reinforcements, or in repairing deteriorated infrastructures by shotcreting process.

Design and Constructibility of an Engineered Cementitious Composite Produced with Cement-based Mortar Matrix and Synthetic Fibers (시멘트계 모르타르 매트릭스를 활용한 섬유복합재료 ECC(Engineered Cementitious Composite)의 설계와 시공 성능)

  • Kim, Yun-Yong
    • Composites Research
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    • v.20 no.2
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    • pp.21-26
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    • 2007
  • This paper summarizes the design procedure and constructibility of an ECC (Engineered Cementitious Composite), which is a synthetic fiber-reinforced composite produced with the Portland cement-based mortar matrix. This study employs a stepwise method to develop useful ECC in construction field, which possesses different fluid properties to facilitate diverse types of processing (i.e., self-consolidating or spray processing). To control the rheological properties of the composite, the aggregates and reinforcing fibers were initially selected based on micromechanical analysis and steady-state cracking theory. The stability and consequent viscosity of the suspensions were then mediated by optimizing the dosage of the chemical and mineral admixtures. The rheological properties altered through this approach were revealed to be effective in obtaining ECC-hardened properties, represented by pseudo strain-hardening behavior in uniaxial tension, allowing the readily achievement of the desired function of the fresh ECC.

Valorization of marble's waste as a substitute in sand concrete

  • Ouassila, Boughamsa;Houria, Hebhoube;Leila, Kherref;Mouloud, Belachia;Assia, Abdelouahed;Chaher, Rihia
    • Advances in concrete construction
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    • v.9 no.2
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    • pp.217-225
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    • 2020
  • The recovery of waste proves a solution with two impacts: the environmental impact by the reduction of pollution and the gain of the occupied space by this waste, and the economic impact by the use of these lasts in the building and in the area of public works. The present research consists in recovering a waste marble (thrown powder exposed to the different meteorological phenomena) generated by the quarry marble of Fil-fila, located at the east side of Skikda in the north-east of Algeria, and add it, as sand in the composition of sand concrete. To carry out this research, we analyzed the evolution brought by the substitution of ordinary sand by marble waste sand, with 25%, 50%, 75% and 100% on the properties in the fresh state (density, workability and air content) and in the cured state (compressive strength, tensile strength, surface hardness and sound velocity). For durability we tested water absorption by immersion and chloride penetration. The results obtained are compared with control samples of 0% of substitution rate. In order to have a good filling of the voids in the granular skeleton; we added a quantity of limestone recycled fines from the quarries and for a good workability a super-plasticizing additive. The results showed that the partial substitution modified both the fresh and the hardened characteristics of the tested concretes, the durability parameters also improved.