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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Concrete Structures and Materials
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Journal DOI :
Korea Concrete Institute
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Volume & Issues
Volume 4, Issue 2 - Dec 2010
Volume 4, Issue 1 - Jun 2010
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Exploiting the Potentials of Rice Husk Ash as Supplement in Cement for Construction in Nigeria
Akindahunsi, Akindehinde Ayotunde ; Alade, Oluwotosin ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 3~8
DOI : 10.4334/IJCSM.2010.4.1.003
This paper present the results of investigation on the use of rice husk ash as a partial substitute for cement in construction. One hundred and eighty specimens of concrete cubes were cast. 0, 5, 10, 15, and 20% partial replacement of cement with rice husk ash were carried at 1:2:4 mixes by weight with 0.60, 0.65, 0.70 water/cement ratio. The results indicated that compressive strengths of cubes at 0.6, water/cement were higher than 0.65 and 0.70. Also 5% partial replacement cement with rice husk ash at
day average compressive strength value of
compared well with 0% partial replacement of cement with rice husk ash of
. This shows that at 5% partial replacement of cement with rice husk ash can be used for structural concrete and at 15% replacement or more it can be used for non - structural construction works or light weight concrete construction. The cost analysis shows substantial amount of savings for the country.
Effect of Steam Curing on Concrete Piles with Silica Fume
Yazdani, N. ; F. Asce, M. Filsaime ; Manzur, T. ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 9~15
DOI : 10.4334/IJCSM.2010.4.1.009
Silica fume is a common addition to high performance concrete mix designs. The use of silica fume in concrete leads to increased water demand. For this reason, Florida Department of Transportation (FDOT) allows only a 72-hour continuous moist cure process for concrete containing silica fume. Accelerated curing has been shown to be effective in producing high-performance characteristics at early ages in silica-fume concrete. However, the heat greatly increases the moisture loss from exposed surfaces, which may cause shrinkage problems. An experimental study was undertaken to determine the feasibility of steam curing of FDOT concrete with silica fume in order to reduce precast turnaround time. Various steam curing durations were utilized with full-scale precast prestressed pile specimens. The concrete compressive strength and shrinkage were determined for various durations of steam curing. Results indicate that steam cured silica fume concrete met all FDOT requirements for the 12, 18 and 24 hours of curing periods. No shrinkage cracking was observed in any samples up to one year age. It was recommended that FDOT allow the 12 hour steam curing for concrete with silica fume.
Experimental Lnvestigation on Mechanical Characteristics and Environmental Effects on Rubber Concrete
Khorrami, Morteza ; Vafai, Abolhassan ; Khalilitabas, Ahmad A. ; Desai, Chandrakant S. ; Ardakani, M. H. Majedi ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 17~23
DOI : 10.4334/IJCSM.2010.4.1.017
The feasibility of the use of scrap tire rubber in concrete was investigated. The tests conducted in two groups: replacing of coarse aggregates with crumb rubber and cement particles with rubber powder. To distinguish the properties of new concrete, the following mechanical and durability tests were designed: compressive, tensile and flexural strength, permeability and water absorption. Rubber addition could affect the concrete properties depend on the type and percentage of the rubber added. Although the rubber addition modifies the mechanical characteristics of concrete in a way, but higher rubber content could not be useful. Concrete durability showed more dependency to the type of rubber instead of percentage of rubber. Moreover, to optimize the mechanical and durability of rubberized concrete, the useful percentage of rubber has been recommended.
Interpreting Conservativeness in Design Criteria for Flexural Strengthening of RC Structures Using Externally Bonded FRP
Kansara, Kunal D. ; Ibell, Tim J. ; Darby, Antony P. ; Evernden, Mark ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 25~36
DOI : 10.4334/IJCSM.2010.4.1.025
This paper presents the influence of various flexural strengthening design criteria specified by three important design guidelines (ACI440, TR55, FIB14) on the resulting strength, ductility and conservativeness of FRP strengthened RC elements. Various generalised mathematical relations in non-dimensional form are presented that can be employed to develop design aids for the FRP-strengthening process. A design methodology is prescribed based on these equations enabling the designer to optimally and intuitively incorporate sufficient ductility while designing for strength. In order to better interpret conservativeness within design codes, four distinct levels of embedded conservativeness are identified, which cover the entire range of sources of conservativeness. Finally, a detailed parametric study is presented, using the proposed design equations and methodology, to determine the influence of each of these four levels of conservativeness on final design solutions. Specific criteria that are useful while calibrating design guidelines are also presented.
Mechanical Properties of Hydrated Cement Paste: Development of Structure-property Relationships
Ghebrab, Tewodros T. ; Soroushian, Parviz ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 37~43
DOI : 10.4334/IJCSM.2010.4.1.037
Theoretical models based on modern interpretations of the morphology and interactions of cement hydration products are developed for prediction of the mechanical properties of hydrated cement paste (hcp). The models are based on the emerging nanostructural vision of calcium silicate hydrate (C-S-H) morphology, and account for the intermolecular interactions between nano-scale calcium C-S-H particles. The models also incorporate the effects of capillary porosity and microcracking within hydrated cement paste. The intrinsic modulus of elasticity and tensile strength of hydrated cement paste are determined based on intermolecular interactions between C-S-H nano-particles. Modeling of fracture toughness indicates that frictional pull-out of the micro-scale calcium hydroxide (CH) platelets makes major contributions to the fracture energy of hcp. A tensile strength model was developed for hcp based on the linear elastic fracture mechanics theories. The predicted theoretical models are in reasonable agreements with empirical models developed based on the experimental performance of hcp.
Study of the Anisotropy of the Roller Compacted Concrete (RCC) for Pavement
Zdiri, Mustapha ; Abriak, Nor-edine ; Ouezdou, Mongi Ben ; Neji, Jamel ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 45~49
DOI : 10.4334/IJCSM.2010.4.1.045
The roller compacted concrete (RCC) is supposed to be isotropic, whereas the compaction of this material, which is achieved using the same machines used for the soil, appears only unidirectional, making the RCC an anisotropic material. In this experimental work, the influence of the phenomenon of compaction on the isotropy of the RCC is studied. This study was carried out through an evaluation of the compressive strengths and ultrasonic tests which were used for measurements of the elastic modulus and the dynamic Poisson's ratio of the RCC as well as a qualitative judgement of the RCC aspect at the hardened state. The results of this work proved the anisotropy of the RCC and they showed the sensitivity of the mechanical strengths and the elastic modulus to the compaction direction.
Experimental and SEM Analyses of Ground Fly Ash in Concrete
Brueggen, Beth ; Kang, Thomas H.K. ; Ramseyer, Chris ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 51~54
DOI : 10.4334/IJCSM.2010.4.1.051
Fly ash is used in concrete to improve the fresh and hardened properties of concrete, including workability, initial hydration temperature, ultimate strength and durability. A primary limitation on the use of large quantities of fly ash in blended cement concrete is its slow rate of strength gain. Prior studies investigated the effects of grinding fly ash and fly ash fineness on the performance of concrete containing fly ash. This study aims to discover the sources of those effects, to verify the compressive strength behavior of concrete made with raw and processed Class C fly ash, and to investigate the properties of fly ash particles at the microscopic level. Concrete cylinder test results indicate that grinding fly ash can significantly benefit the early age strength as well as the ultimate strength of concrete with ground fly ash. Therefore, it is demonstrated that grinding fly ash increases its reactivity. Scanning Electron Microscopy was then used to investigate the physical effects of the grinding process on the fly ash particles in order to identify the mechanism by which grinding leads to improved concrete properties.
Analysis of the Foam Generated Using Surfactant Sodium Lauryl Sulfate
Ranjani, G. Indu Siva ; Ramamurthy, K. ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 55~62
DOI : 10.4334/IJCSM.2010.4.1.055
The performance evaluation of a sodium lauryl sulfate to qualify as a foaming agent is presented in this paper. When new surfactants are used a systematic study of production parameters on the foam characteristics needs to be undertaken unlike proprietary foaming agents and foam generator for which manufacturer has predefined the parameters. The relative influence of the foam parameters and optimization of factors were carried out through a systematic experiment design. The foam production parameters namely foam generation pressure and dilution ratio of foaming agents are observed to have significant effect on all foam characteristics with the exception of foam output rate on which only foam generation pressure has influence. The foam with good initial foam density need not necessarily be stable foam. The optimum levels of foam production parameters are determined for the surfactant Sodium lauryl sulfate which can be used to produce stable foam for foam concrete production.
Simplified Design Equation of Lap Splice Length in Compression
Chun, Sung-Chul ; Lee, Sung-Ho ; Oh, Bo-Hwan ;
International Journal of Concrete Structures and Materials, volume 4, issue 1, 2010, Pages 63~68
DOI : 10.4334/IJCSM.2010.4.1.063
With the emergence of ultra-high strength of concrete, the compression lap splice has become an important area of interest. According to ACI 318-08, a compression splice can be longer than a tension splice when high-strength concrete is used. By reevaluating the test results of compression splices and performing regression analysis, a simplified design equation for splice length in compression was developed based on the basic form of design equations for development/splice lengths of deformed bars and hooks in tension. A simple linear relation between
was assumed, and yields good values for the correlation coefficient and the mean and the COV (coefficient of variation) of the ratios of tests to predictions of splice strengths in compression. By including the 5% fractile coefficient of 0.83, a design equation for splice length in compression was developed. The splice length calculated using the proposed equation has a reliability that is equivalent to other provisions for reinforcing bars.