Conference Publications

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https://hdl.handle.net/20.500.14170/379

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Browsing Conference Publications by Author "Andrei Victor Sandu"
  • Publication
    Effect of crumb rubber on compressive strength of fly ash based geopolymer concrete
    ( 2016)
    Ahmad Azrem Azmi
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Che Mohd Ruzaidi Ghazali
    ;
    Andrei Victor Sandu
    ;
    Kamarudin Hussin
    This study explores the effect of different percentage of crumb rubber on compressive strength of fly ash based geopolymer concrete. This research attempted to produce rubberized geopolymer concrete as an environmentally friendly, lightweight and durable product. Crumb rubber with ranged size from 73 μm to 375 μm was used in order to replace fine aggregates in geopolymer concrete. The replacements of crumb rubber were 0%, 5%, 10%, 15% and 20% in the fly ash based geopolymer concrete. The ratio of fly ash to alkaline activator was 2.5 and the ratio of Na2SiO3 to NaOH was fixed at 2.0. After the curing process, the strengths of the samples were tested on days 7 and 28. The results show that there is a reduction in all compressive strength for crumb rubber mixture, but still higher than normal rubberized concrete. Rubberized geopolymer concrete is a suitable solution in some non structural applications.
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  • Publication
    Properties and behavior of geopolymer concrete subjected to explosive air blast loading: a review
    ( 2017)
    Nurul Aida Mohd Mortar
    ;
    Kamarudin Hussin
    ;
    Rafiza Abdul Razak
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Ahmad Humaizi Hilmi
    ;
    Andrei Victor Sandu
    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
    The effect of different ratio bottom ash and fly ash geopolymer brick on mechanical properties for non-loading application
    ( 2017)
    Laila Mardiah Deraman
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Liew Yun Ming
    ;
    Kamarudin Hussin
    ;
    Wan Mastura Wan Ibrahim
    ;
    Andrei Victor Sandu
    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
    The incorporation of Sodium Hydroxide (NaOH) concentration and CaO-Si components on ground granulated blast furnace slag geopolymers
    (IOP Publishing Ltd., 2020)
    Ikmal Hakem Aziz
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Mohd Arif Anuar Mohd Salleh
    ;
    Andrei Victor Sandu
    This paper investigates the incorporation of sodium hydroxide (NaOH) concentration and CaO-Si component on ground granulated blast furnace slag geopolymers (GGBFS). An optimal mechanical property of GGBFS with various NaOH concentrations had been determined by performing a number of compressive strength tests. It was found that GGBFS with 10M NaOH concentration resulted in high compressive strength at 65.31 MPa after 28 days curing. The microstructure analysis of the GGBFS geopolymers using SEM and FTIR revealed the formation of calcium silicate hydrate (Ca5Si6O16(OH)2.4H2O) and calcium carbonate (CaCO3) phase within the geopolymer backbone chain. The optimum NaOH concentration allows the acceptable formation of CaO-Si bond on the GGBFS geopolymers main structure and thus leads to optimum compressive strength.
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