• Title/Summary/Keyword: high strength lightweight concrete

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Properties and Mock-up Test of Lightweight Foamed Concrete Based on Blast Furnace Slag by Crack Reducing Admixture (팽창성 균열저감제를 이용한 고로슬래그 미분말 기반 경량기포 콘크리트의 특성 및 목업실험)

  • Han, Sang-Yoon;Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.17 no.6
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    • pp.507-515
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    • 2017
  • This study is to develop a high quality lightweight foamed concrete that can be applied in the field using EXFG by cracking reducing agent combined with FGD and ALS. First, to increase the volume of foam, the flow and density of the mixture was increased and decreased, respectively. At this time, the effect of substitution ratio of EXFG on fluidity was negligible. The fraction of foam was the highest at EXFG 1%, and the settlement was found to be prevented by the expansion reaction at EXFG 1%. At this time, the ratio of foam was 65%. In the compressive strength, the strengths were similar or decreased when the substitution ratio of EXFG was more than 1%. The apparent density satisfied the KS 0.5 type at the bubble contents was 65%. In case of EXFG substitution, dry shrinkage was decreased by about 10%. As the substitution ratio of EXFG increased, the thermal conductivity increased proportionally.

Tailoring ECC for Special Attributes: A Review

  • Li, Victor C.
    • International Journal of Concrete Structures and Materials
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    • v.6 no.3
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    • pp.135-144
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    • 2012
  • This article reviews the tailoring of engineered cementitious composites (ECC), a type of high performance fiber reinforced cementitious composites with a theoretical design basis, for special attributes or functions. The design basis, a set of analytic tools built on micromechanics, provides guidelines for tailoring of fiber, matrix, and fiber/matrix interfaces to attain tensile ductility in ECC. If conditions for controlled multiple cracking are disturbed by the need to introduce ingredients to attain a special attribute or function, micromechanics then serve as a systematic and rational means to efficiently recover composite tensile ductility. Three examples of ECCs with attributes of lightweight, high early strength, and self-healing functions, are used to illustrate these tailoring concepts. The fundamental approach, however, is broadly applicable to a wide variety of ECCs designed for targeted fresh and/or hardened characteristics required for specific applications.

Structural performance by strengthening types of wood frames using H shaped steel joints (H형강 접합부를 갖는 목조 골조의 보강형식에 따른 구조성능)

  • Kim, Soon-Chul;Moon, Youn-Joon;Yang, Il-Seung;Park, Geun-Hong
    • KIEAE Journal
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    • v.8 no.3
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    • pp.77-83
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    • 2008
  • The effective mixture of structural laminated timber and other materials is expected to extend the potentials of building structures because of the potentials to realize high performance in structural safety. The classical joint types using drift pin and bolts are occurred local failures due to the small bearing area. In result, new joints using H shaped steel were suggested in this research. The objective of this study is to evaluate elasto-plastic behaviors by strengthening types of wood frames with new joints connecting structural laminated timber with H shaped steel. A total of five specimens of about one-second scale were tested. Specimens had columns with 1,050 height and $84mm{\times}100mm$ section, and a beams with 1,950mm length and $130mm{\times}100mm$ section. Also, the specimens were stiffened by brace, hwang-toh brick, and autoclaved lightweight concrete. The results of the test showed that the specimen stiffened with autoclaved lightweight concrete was characterized by fairly good strength and stiffness than those of the other specimens. Initial stiffness of H-2.0D-NS specimen with 2 times inserting length of beam height showed 1.33 times than that of H-1.5D-NS specimen. However, the strength of H-2.0D-NS specimen has not improved too much than H-1.5D-NS specimen.

Experimental Study on the Improvement of Workability of Cementitious Composites Using Nano-bubble Water (나노버블수를 활용한 시멘트 복합체의 작업성 증진에 대한 실험적 연구)

  • Lee, Nankyoung;Kang, Sung-Hoon;Moon, Juhyuk
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.6
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    • pp.27-32
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    • 2021
  • This study was conducted to improve the workability of cementitious composites using nano-bubble water. The used nano-bubble water contains 7% of nano-sized bubbles with an averaged bubble size of 750 nm. Various different types of cementitious composites including ultar-high performance concrete, lightweight cementitious composites, and high-strength mortar have been tested to identify the changes of material properties. From the use of nano-bubble water, it was confirmed that workability has been improved by 3-22%. On the other hand, other material characteristics such as compressive strength did not have noticeable changes. Therefore, it was proposed that the use of nano-bubble water can enhance workability of cementitious composites without having significant impact on other material properties.

Safety Assessments through Acute Oral Toxicity Test and Acute Dermal Toxicity Test of Cement Composite Containing Nano Materials (나노 소재 혼입 시멘트 복합체의 급성경구독성시험 및 급성경피독성시험을 통한 유해성 평가)

  • Jae Hyuck, Sung;Kyung Seuk, Song;Yeonung, Jeong;Sanghwa, Jung;Joo Hyung, Kim
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.411-419
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    • 2022
  • This study conducted acute oral toxicity test and acute dermal toxicity test to evaluate the toxicity of lightweight and high-strength cement composite containing carbon nanotube. It was compared with the toxicity of ordinary concrete that did not contain carbon nanotube. Both lightweight and high-strength cement composite and ordinary concrete were categorized in GHS category 5 as a result of acute oral toxicity test. In addition, no toxic symproms were observed during the acute dermal toxicity test in all specimens, concluding that those were judged to correspond to GHS category 5/unclassified.

Research on the Mechanical Properties of Some New Aluminum Alloy Composite Structures in Construction Engineering

  • Mengting Fan;Xuan Wang
    • Korean Journal of Materials Research
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    • v.34 no.2
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    • pp.72-78
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    • 2024
  • The lightweight and high strength characteristics of aluminum alloy materials make them have promising prospects in the field of construction engineering. This paper primarily focuses on aluminum alloy materials. Aluminum alloy was combined with concrete, wood and carbon fiber reinforced plastic (CFRP) cloth to create a composite column. The axial compression test was then conducted to understand the mechanical properties of different composite structures. It was found that the pure aluminum tube exhibited poor performance in the axial compression test, with an ultimate load of only 302.56 kN. However, the performance of the various composite columns showed varying degrees of improvement. With the increase of the load, the displacement and strain of each specimen rapidly increased, and after reaching the ultimate load, both load and strain gradually decreased. In comparison, the aluminum alloy-concrete composite column performed better than the aluminum alloy-wood composite column, while the aluminum alloy-wood-CFRP cloth composite column demonstrated superior performance. These results highlight excellent performance potential for aluminum alloy-wood-CFRP composite columns in practical applications.

Foamed Concrete with a New Mixture Proportioning Method Comparable to the Quality of Conventional ALC Block (ALC 블록성능의 기포콘크리트 배합설계 연구)

  • Yang, Keun-Hyeok
    • Journal of the Korea Institute of Building Construction
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    • v.15 no.1
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    • pp.1-7
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    • 2015
  • The objective of this study is to develop a high-performance foamed concrete made with a new mixture proportioning as an alternative of autoclaved lightweight concrete (ALC) block. For the early-strength gain of the foamed concrete under an atmospheric curing condition, the binders and chemical agents were specially contrived as follows: 3% anhydrous gypsum was added to ordinary portland cement (OPC) in which $3CaO{\cdot}SiO_2$ content was controlled to be above 60%; and the content of polyethylene glycol alkylether in a polycarboxylate-based water-reducing agent was modified to be 28%. Using these binders and chemical agents, 11 mixes were prepared with the parameters of W/B ratio (30% to 20% in a interval of 2.5%) and unit binder content ($400kg/m^3$ to $650kg/m^3$ in a interval of $50kg/m^3$). The quality and availability of the mixed foamed concrete were examined according to the minimum requirements specified in the KS for ALC block and existed conventional foamed concrete. The measured properties satisfied the minimum requirement of KS for ALC block and proved that the developed high-performance foamed concrete had considerable potential for practical application.

Experimental Study on the Development and Evaluation of Lt.Wt.& High Strength Composites Utilizing By-Products and Calcium Silicates for Construction Materials(1) (산업부산물 및 규산칼슘계 재료를 이용한 건재용 경량.고강도 복합체의 개발.평가에 관한 실험적 연구(기 1))

  • 박승범
    • Magazine of the Korea Concrete Institute
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    • v.6 no.4
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    • pp.141-152
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    • 1994
  • The results of an experimental study on the development and the evaluation of lightweight and high strength composites utilizing by-products and calcium silicates for construction materials are presented in this paper. The composites using early strength portland cement, by-Products( f1y ash, silica fume), silica powder, quick lime, gypsum, A1 powder and fibers(PAN-derived CF, alkali-resistance GF) were prepared using various mixing conditions. As the test results show, PAN-derived CF and alkali-resistance GF were suitable for rein-forcing fiber of the composites. And the mechanical properties,such as compressive tensile flexural strength, and toughness of Lt. Wt. fiber reinforced calcium silicates cement comp-osites were improved by increasing the fly ash and silica fume contents, and fiber contents, especially by increasing fiber contents the toughness of the composites were remarkably in-creased. Also, compressive tensile flexural strength,and toughness of the composites rein-forcing PAN-derived CF were higher than those of the composites reinforcing alkali-resistance GF..

Physical Properties and Quality Control of Foamed Concrete with Fly Ash for Cast-in-Site (플라이애쉬를 혼입한 현장타설 경량기포콘크리트의 물리적 특성 및 품질관리)

  • 이도헌;전명훈;고진수
    • Journal of the Korea Concrete Institute
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    • v.13 no.1
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    • pp.69-76
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    • 2001
  • Foamed concrete for cast-in-site, which shows excellent lightweight, thermal insulation, noise insulation, constructability and cost efficiency, has been applied as thermal insulation or filling material for On-dol. However, the technology is too insufficient to obtain the high level of quality, and serious problems often occur in quality control at sites. It, thus, is necessary to establish the proper and reasonable quality control method for ensuring the required quality, based on the investigation on the physical properties and their reciprocal relation. This study aims to settle the quality control method in case of applying FA foamed concrete replacing 40% by weight with fly-ash as the filling material for On-dol. The results of the study include the correlation among flow, as-placed density and foam ratio of fresh foamed concrete, the correlation between physical properties before hardening and after 28-day, provision of an equation to estimate 28-day compressive strength early with 7-day compressive strength, and suggestion of quality criteria for the revision of KS on foamed concrete for cast-in-site.

Development of Nanomodified Snow-Melting Concrete Using Low-Temperature Phase-Change Material Impregnated Lightweight Aggregate (저온 상변화 물질 함침 경량골재를 이용한 나노 개질 융설 콘크리트 개발)

  • Kyoung, Joo-Hyun;Kim, Sean-Mi;Hu, Jong-Wan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.42 no.6
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    • pp.787-792
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    • 2022
  • In winter, the excessive use of deicing salt deteriorates concrete pavement durability. To reduce the amount of deicing salt used, phase-change materials (PCMs) potentially offer an alternative way to melt snow through their latent heat storage characteristics. In this research, thermal energy storage concrete was developed by using PCM-impregnated expanded clay as 50 % replacement to normal aggregate by volume. In addition, to improve the thermal efficiency of PCM lightweight aggregate (PCM-LWA)-incorporated concrete, multi-walled carbon nanotubes (MWCNTs) were incorporated in proportions of 0.10 %, 0.15 %, and 0.20 % by binder weight. Compressive strength testing and programmed thermal cycling were performed to evaluate the mechanical and thermal responses of the PCM-LWA concrete. Results showed a significant strength reduction of 54 % due to the PCM-LWA; however, the thermal performance of the PCM-LWA concrete was greatly improved with the addition of MWCNTs. Thermal test results showed that 0.10 % MWCNT-incorporated concrete had high thermal fatigue resistance as well as uniform heat flow, whereas specimens with 0.15 % and 0.20 % MWCNT content had a reduced thermal response due to supercooling when the ambient temperature was varied between -5℃ and 10℃.