Zarina Yahya
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Preferred name
Zarina Yahya
Official Name
Zarina, Yahya
Alternative Name
Yahya, Zarina
Zarina, Y.
Zarina, Yahya
Main Affiliation
Scopus Author ID
51162069600
Researcher ID
DXZ-6436-2022

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The ProPerTies of Ground GranulaTed BlasT furnace slaG liGhTweiGhT aGGreGaTe (Gla) aT Various Molar raTio and iTs aPPlicaTion in concreTe

2023-01-01 , Rafiza Abd Razak , Hassan M.A. , Mohd. Mustafa Al Bakri Abdullah , Zarina Yahya , Ariffin M.A.M. , Ahmad Faizal Mansor , Hao D.L.C.

The effects of supplementary cementitious materials (SCM) on the characteristics and internal structure of synthetic aggregate made from ground granulated blast furnace slag are investigated in this study (GGBS). Due to its high pozzolanic activity, GGBS was shown to be superior to other SCM materials, enhancing both the strength and durability of synthetic aggregate. Because sintering uses a lot of energy and generates a lot of pollutants, using a cold-bonded approach to make low density lightweight aggregates is particularly significant from an economic and environmental standpoint. Thus, the utilisation of ground granulated blast furnace slag (GGBS) as a substitute material in the production of green artificial lightweight aggregate (GLA) using the cold bonding method was discussed in this work. Admixtures of ADVA Cast 203 and Hydrogen Peroxide were utilised to improve the quality of GLA at various molar ratios. The freshly extracted GLA was then evaluated for specific gravity, water absorption, aggregate impact, and aggregate crushing in order to determine the optimal proportion blend. As a result, the overall findings offer great application potential in the development of concrete (GCLA). It has been determined that aggregates with a toughness of 14.6% and a hardness of 15.9% are robust. The compressive strength test found that the GCLA has a high strength lightweight concrete of 37.19 MPa and a density of 1845.74 kg/m3. The porous features developed inside the internal structure of GLA have led to GCLA’s less weight compared to conventional concrete.

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The Effect of NaOH Concentration on Palm Oil Boiler Ash (POBA) based Geopolymer Artificial Aggregate

2024-04-19 , Hao D.L.C. , Rafiza Abd Razak , Zarina Yahya , Mohd. Mustafa Al Bakri Abdullah , Subaer

Industrial wastes or by-products can be used to create artificial aggregates. Solid waste created by the palm oil industry is a significant environmental problem that requires immediate and long-term solutions. The optimal ratio of geopolymer-based palm oil boiler ash (POBA) aggregate in terms of specific gravity, water absorption, and aggregate impact value was explored in this work. Because of its high percentages of silica oxide (SiO2) and aluminium oxide (Al2O3), POBA was chosen as the primary precursor for the geopolymer (Al2O3). The POBA aggregate with the lowest specific gravity was 1.662, while all of the geopolymer-based POBA aggregates had specific gravities below 2. The geopolymer-based POBA aggregate absorbs more water than the natural aggregate. The aggregate effect value for sodium hydroxide concentrations (6M, 8M, 10M, 12M, 14M) is less than 30%, which is considered strong.

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Investigation of influence factors and surface treatment on palm oil boiler ash (POBA) based geopolymer artificial aggregate: Impregnation vs. coating method

2023-05-01 , Ling D.C.H. , Rafiza Abd Razak , Zarina Yahya , Mohd. Mustafa Al Bakri Abdullah , Chaiprapa J. , Phan V.T.A. , Mohamed R. , Aziz I.H.

Producing man-made aggregates from industrial waste or biomass is feasible. Solid waste from the palm oil industry is a significant environmental problem requiring both immediate and long-term solutions. This study investigated the effect of influence factors of palm oil boiler ash (POBA)-based geopolymer aggregate based on its physico-mechanical, thermal, and characterization properties. The cold-bonding method was chosen due to its lower energy consumption. All POBA-based geopolymer aggregates had specific gravities below 2.0, classifying them as lightweight aggregates. Some ratios provide aggregate impact values (AIV) that are less than 30% and are characterised as strong aggregates. The overall thermal conductivity obtained from the POBA-based geopolymer is 0.161–0.243 W/m.K. The optimum ratio of POBA-based geopolymer aggregate microstructure had a denser and more complex structure. The high water absorption of the POBA-based geopolymer aggregate necessitated the development of additional surface treatment techniques, including vacuum impregnation and coating. The vacuum impregnation process with geopolymer enhanced aggregate characteristics. Microstructure analysis indicated that geopolymer had filled the voids and strengthen the matrix, as proven through Micro-XRF analysis. The properties of concrete made with treated POBA-based geopolymer aggregate can be used as a structural application.

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