Now showing 1 - 10 of 74
  • Publication
    Properties and behavior of geopolymer concrete subjected to explosive air blast loading: a review
    The severe damage to civilian buildings, public area, jet aircraft impact and defense target under explosive blast loading can cause a huge property loss. Most of researcher discusses the topics on design the concrete material model to sustain againts the explosive detonation. The implementation of modern reinforcement steels and fibres in ordinary Portland cement (OPC) concrete matrix can reduce the extreme loading effects. However, most researchers have proved that geopolymer concrete (GPC) has better mechanical properties towards high performance concrete, compared to OPC. GPC has the high early compressive strength and high ability to resist the thermal energy from explosive detonation. In addition, OPC production is less environmental friendly than geopolymer cement. Geopolymer used can lead to environmental protection besides being improved in mechanical properties. Thus, this paper highlighted on an experimental, numerical and the analytical studies cause of the explosive detonation impact to concrete structures.
  • Publication
    Finite element analysis on structural behaviour of geopolymer reinforced concrete beam using Johnson-Cook damage in Abaqus
    This paper details a finite element analysis of the behaviour of Si-Al geopolymer concrete beam reinforced steel bar under an impulsive load and hyper velocity speed up to 1 km/s created by an air blast explosion. The initial torsion stiffness and ultimate torsion strength of the beam increased with increasing compressive strength and decreasing stirrup ratio. The study involves building a finite element model to detail the stress distribution and compute the level of damage, displacement, and cracks development on the geopolymer concrete reinforcement beam. This was done in ABAQUS, where a computational model of the finite element was used to determine the elasticity, plasticity, concrete tension damages, concrete damage plasticity, and the viability of the Johnson-Cook Damage method on the Si-Al geopolymer concrete. The results from the numerical simulation show that an increase in the load magnitude at the midspan of the beam leads to a percentage increase in the ultimate damage of the reinforced geopolymer beams failing in shear plastic deformation. The correlation between the numerical and experimental blasting results confirmed that the damage pattern accurately predicts the response of the steel reinforcement Si-Al geopolymer concrete beams, concluded that decreasing the scaled distance from 0.298 kg/m3 to 0.149 kg/m3 increased the deformation percentage.
  • Publication
    The effect of various waste materials' contents on the attenuation level of anti-radiation shielding concrete
    ( 2013)
    Ali Azeez
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    Kahtan Mohammed
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    ; ;
    Sandu, Andrei Victor
    ;
    Samples of concrete contain various waste materials, such as iron particulates, steel balls of used ball bearings and slags from steel industry were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation sources comprised 137Cs and 60Co radioactive elements with photon energies of 0.662 MeV for 137Cs and two energy levels of 1.17 and 1.33 MeV for the 60Co. Likewise the mean free paths for the tested samples were obtained. The aim of this work is to investigate the effect of the waste loading rates and the particulate dispersive manner within the concrete matrix on the attenuation coefficients. The maximum linear attenuation coefficient (μ) was attained for concrete incorporates iron filling wastes of 30 wt %. They were of 1.12 ± 1.31×10-3 for 137Cs and 0.92 ± 1.57 × 10-3 for 60Co. Substantial improvement in attenuation performance by 20%-25% was achieved for concrete samples incorporate iron fillings as opposed to that of steel ball samples at different (5%-30%) loading rates. The steel balls and the steel slags gave much inferior values. The microstructure, concrete-metal composite density, the homogeneity and particulate dispersion were examined and evaluated using different metallographic, microscopic and measurement facilities.
  • Publication
    Effects of trans-polyoctylene rubber in polypropylene/recycled acrylonitrile butadiene/rice husk powder composites
    Composites of polypropylene/Acylonitrile butadiene rubber/Rice husk powder/ (PP/NBRr/RHP) with and without trans-polyoctylene rubber (TOR) were prepared, and the effects of trans-polyoctylene rubber were investigated. By using rice husk powder of 150300μm, five different compositions of PP/NBRr/RHP composites (i.e.100/0, 80/20, 70/30, 60/40 and 40/60 phr) were prepared in an internal mixer at 180 °C and 50 rpm rotor speed. The results indicate that the incorporation of TOR improved the tensile properties of PP/NBRr/RHPcomposites. Scanning electron microscopy of the fractured surfaces proved that TOR promoted good adhesion between the PP-NBRr matrices and RHP.
  • Publication
    Chemically chitosan modified with methyl methacrylate and its effect on mechanical and thermal properties of polypropylene composites
    ( 2013)
    Faisal Amri Tanjung
    ;
    Salmah Husseinsyah
    ;
    ;
    Iqmal Tahir
    Effects of methyl methacrylate on the properties of chitosan-filled polypropylene (PP) composites has been investigated. Mechanical and thermal properties of the composites were analyzed according to ASTM D 638-91, thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). The results showed that tensile strength of PP composites decreased upon the addition of chitosan, while Young's modulus improved. At a similar filler loading, the treated PP/chitosan composites were found to have higher tensile strength and Young's modulus as compared with the untreated composites. Thermal analysis results showed that thermal stability and crystallinity of the treated composites were higher than the untreated ones. Scanning electron microscopy (SEM) and Fourier transforms infrared (FTIR) studies revealed less detached filler from matrix on tensile surface of the treated composites as an evidence of enhanced filler-matrix interfacial adhesion due to formation of ester-bridge between the chitosan and the methyl methacrylate.
  • Publication
    Fly ash porous material using geopolymerization process for high temperature exposure
    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.
  • Publication
    Fly Ash porous material using geopolymerization process for high temperature exposure
    ( 2012-04-10) ; ; ;
    Mohamed Bnhussain
    ;
    Che Mohd Ruzaidi Ghazali
    ;
    Mohd Izzat Ahmad
    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.
  • Publication
    Thermal insulation properties of insulated concrete
    ( 2019-01-01)
    Shahedan N.F.
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    ; ;
    Kusbiantoro A.
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    ;
    Sandu A.V.
    ;
    Naveed A.
    In building development, concrete is world most reliable, durable and versatile in construction materials. However, the heating and cooling system of the building is influenced by outside temperature due to extreme weather or areas condition leads to the consumption of a lot of electrical power. Thermally insulated concretes represent alternative construction materials to improve the thermal efficiency in building development. Various construction materials have different thermal insulation properties and thus, their suitability for various conditions vary. Thermal insulation properties are generally identified through specific heat, thermal conductivity, thermal diffusivity, thermal expansion, and mass loss. This paper present review the thermal insulation properties of variations insulated concrete are presently in growing demand of researchers to comfort and resolve prescribed issues related to insulated concrete in enhancing thermal insulation properties as a passive energy saving building.
  • Publication
    The effect of different ratio bottom ash and fly ash geopolymer brick on mechanical properties for non-loading application
    This paper studies the finding of strength and water absorption of geopolymer bricks using bottom ash and fly ash as a geopolymer raw material for non-loading application with minimum strength. The study has been conducted to produce bottom ash and fly ash geopolymer bricks by varying the ratio of fly ash-to-bottom ash, solid-to-liquid and sodium silicate (Na2SiO3)-to-sodium hydroxide (NaOH) in the mixing process. The compressive strength range between 3.8-4.5 MPa was obtained due to the minimum strength of non-loading application with 70°C curing temperature within 24 hours at 7 days of ageing. The optimum ratio selected of bottom ash-to-fly ash, solid-to-liquid and Na2SiO3-to-NaOH are 1:2, 2.0 and 4.0 respectively. The water absorption result is closely related to the amount of bottom ash used in the mix design.
  • Publication
    Mechanical and microstructural evaluations of lightweight aggregate geopolymer concrete before and after exposed to elevated temperatures
    ( 2013)
    Omar Abdulkareem
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    ; ; ;
    Mohammed Binhussain
    This paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates.