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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Surface resistivity and ultrasonic pulse velocity evaluation of reinforced opc concrete and reinforced geopolymer concrete in marine environment

2021-01-01 , Mohd Badrul Hisyam Ab Manaf , Zarina Yahya , Rafiza Abd Razak , Mohd. Mustafa Al Bakri Abdullah , Ariffin N.F. , Muhammad Munsif Ahmad , Chong Y.C.

The concrete structures that are built along the seaside often suffer from reduced service life due to inadequate durability against deterioration. This research reports the findings of concrete resistivity and quality using two Non-Destructive Testing (NDT) measures applied to Reinforced Geopolymer and Ordinary Portland Cement (OPC) concrete in the marine environment. In addition, the relationship between Reinforced Geopolymer and Reinforced OPC concrete was statistically discussed in-terms of strength and direction. The testing was carried out using a Proceeq Resipod Wenner 4-probe to measure Surface Resistivity (SR) and Ultrasonic Pulse Velocity (UPV), respectively. The testings were carried out on beam shaped samples of OPC and Geopolymer concrete that were immersed in seawater over a period of 90 days with similar curing condition. It was found from the present investigation that the maximum SR and maximum UPV values acquired for both the Reinforced OPC and Reinforced Geopolymer concrete are 2.73 kΩcm and 2.07 kΩcm, as well as 4.18 km/s and 4.05 km/s, respectively. It is apparent from the study that both concrete is comparable in terms of quality and surface resistivity.

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The effect Na2SiO3/NaOH ratio to specific gravity and water absorption of artifiticial geopolymer aggregate dolomite based

2017-09-26 , Aiman Mahmad Nor , Zarina Yahya , Mohd. Mustafa Al Bakri Abdullah

Industry such as construction and materials had depended a lot on the available aggregate. The use of aggregate need to be designed so that it have a well sustainable system with good physical properties. This paper is using dolomite to produce an artificial aggregate. The dolomite based artificial aggregate is produced using geopolymer as a hardened process. The dolomite base artificial aggregate is tested with a different alkaline activator to find water absorption and density. The lowest water absorption of dolomite artificial aggregate is 14%. The specific gravity of the artificial aggregate tested are lower when the sodium silicate is decreasing. The lowest density of artificial aggregate obtain are with 2.03 g/cm3.

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Article the effects of various concentrations of naoh on the inter-particle gelation of a fly ash geopolymer aggregate

2021-03-01 , Alida Abdullah , Kamarudin Hussin , Mohd. Mustafa Al Bakri Abdullah , Zarina Yahya , Sochacki W. , Rafiza Abd Razak , BÅ‚och K. , Fansuri H.

Aggregates can be categorized into natural and artificial aggregates. Preserving natural resources is crucial to ensuring the constant supply of natural aggregates. In order to preserve these natural resources, the production of artificial aggregates is beginning to gain the attention of researchers worldwide. One of the methods involves using geopolymer technology. On this basis, this current research focuses on the inter-particle effect on the properties of fly ash geopolymer aggregates with different molarities of sodium hydroxide (NaOH). The effects of synthesis parameters (6, 8, 10, 12, and 14 M) on the mechanical and microstructural properties of the fly ash geopolymer aggregate were studied. The fly ash geopolymer aggregate was palletized manually by using a hand to form a sphere-shaped aggregate where the ratio of NaOH/Na2SiO3 used was constant at 2.5. The results indicated that the NaOH molarity has a significant effect on the impact strength of a fly ash geopolymer aggregate. The highest aggregate impact value (AIV) was obtained for samples with 6 M NaOH molarity (26.95%), indicating the lowest strength among other molarities studied and the lowest density of 2150 kg/m3 . The low concentration of sodium hydroxide in the alkali activator solution resulted in the dissolution of fly ash being limited; thus, the inter-particle volume cannot be fully filled by the precipitated gels.

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The Influence of Cement Content to Properties of High Strength Anti Washout Concrete (HSAWC)

2024-04-19 , Khairunnisa Muhamad , Muhammad Haikal Farizad , Zarina Yahya , Liyana Ahmad Sofri

The high strength of concrete required a lot of cement content to increase its strength but not for the anti washout concrete (AWC) or underwater concrete (UWC). AWC will face another problem which is higher cement content could make the segregation to occur. This segregation process will give bad impact to the strength of the AWC. This research studied on four different cement content to examine: 450 kg/m3, 500 kg/m3, 550 kg/m3 and 600 kg/m3 towards its fresh and hardened properties of concrete. Superplasticizer is used as water reducing agent in the mix proportions to achieve high strength and self-consolidated concrete. Apart from that, there are two types of concrete samples produced, the air sampling concrete and underwater sampling concrete which have the same mix proportion. The overall results show a good correlation between the cement content in the mix and the strength of the air sampling concrete achieved. However, anti washout concrete having issues which is segregation. This segregation had affected the strength of the concrete. In conclusion, Anti washout concrete shows that optimal cement content without any viscocity modifying agent (VMA) is at 550 kg/m3

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