Liew Yun Ming
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Liew Yun Ming
Official Name
Liew Yun Ming
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Yun-Ming, Liew
Liew, Y. M.
Yun Ming, Liew
Ming, Liew Yun
Liew, Yun Ming
Ming, L. Y.
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Scopus Author ID
57204242778
Researcher ID
S-7164-2019

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Towards greener one-part geopolymers through solid sodium activators modification

2022-12-10 , Ooi Wan En , Liew Yun Ming , Heah Cheng Yong , Ho Li Ngee , Mohd. Mustafa Al Bakri Abdullah , Bin Khalid M.S. , Foo Kai Loong , Ong Shee Ween , Pei Seng T. , Hang Yong Jie , Khairunnisa Zulkifly

This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.

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Acid-resistance of one-part geopolymers: Sodium aluminate and carbonate as alternative activators to conventional sodium metasilicate and hydroxide

2023-11-10 , Wan-En O. , Liew Yun Ming , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Ho Li Ngee , Pakawanit P. , Wei Ken P. , Khalid M.S. , Md Razi H. , Lee W.H. , Tan Soo Jin , Shee-Ween O. , Yong-Jie H.

In this study, the durability of one-part geopolymers (OPGs) made from high calcium fly ash is assessed by investigating their resistance to acid attacks. The predominant use of less environmentally sustainable sodium metasilicate (Na2SiO3) and sodium hydroxide (NaOH) in OPG, along with the limited understanding about the influence of solid alkali activators on OPG's acid resistance propelled the investigation and comparison of acid resistance of OPGs activated using both conventional activators and potential alternatives like sodium aluminate (NaAlO2) and sodium carbonate (Na2CO3). The OPGs developed were exposed to sulphuric acid (H2SO4) solution for 28 days. The MH sample (activated with Na2SiO3 and NaOH) was vulnerable to acid attack, with a 66% compressive strength drop after 5% H2SO4 solution exposure, due to high sorptivity. In contrast, the MA sample (activated with Na2SiO3 and NaAlO2) demonstrated excellent acid resistance, with only a 32% strength reduction, attributed to its Al-rich hydrated gel. The MC sample (activated with Na2SiO3 and Na2CO3) exhibited a 41% strength reduction, where the formation of calcite reduced extensive ion exchange, gradually mitigated deterioration. The residual compressive strength of MA and MC samples increased by 7% and 9% from 7 to 28 days of immersion in 5% H2SO4 solution, respectively. The NaAlO2 and Na2CO3 are potential activators for OPG, serving as alternative construction materials to OPC and traditional geopolymers in acidic environments.

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Strength optimization and key factors correlation of one-part fly ash/ladle furnace slag (FA/LFS) geopolymer using statistical approach

2023 , Hang Yong Jie , Heah Cheng Yong , Liew Yun Ming , Mohd. Mustafa Al Bakri Abdullah , Lee Yeng Seng , Kong Ern-Hun , Ong Shee Ween , Ooi Wan En , Ng Hui Teng , Ng Yong Sing

The utilization of ladle furnace slag (LFS) in one-part geopolymer technology has not been reported. The study of the cause-and-effect relationship between the mixing ratio is therefore important. The present work optimized one-part fly ash (FA)/LFS geopolymer with 33 full factorial design using variance analysis (ANOVA) to predict the key engineering properties of the one-part geopolymer with satisfactory precision. Three factors, which are alkali activator to aluminosilicate sources (AA/AS), sodium metasilicate to sodium hydroxide, Na2SiO3 to NaOH (SM/SH) and water to binder (W/B) ratios, were considered. The AA/AS, W/B and interrelationship between AA/AS and W/B ratios were the most significant factors influencing the key engineering properties. The one-part geopolymer with AA/AS, SM/SH and W/B ratios of 0.20, 5.0 and 0.25 were concluded as an optimal response to achieve a good compressive strength of 38.8 MPa after 28 days. The microstructural and phase analysis indicated that the LFS participated moderately in geopolymerization reaction with the formation of calcium silicate hydrate (C–S–H) and sodium aluminate silicate hydrate (N-A-S-H). The optimized one-part FA/LFS geopolymer met the minimum requirement of ASTM C1157 (>28.0 MPa) for a functional construction binder. The outcome of the paper offers a guideline to the construction industry to maximize the use of LFS to prepare green construction binder.

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Towards greener one-part geopolymers through solid sodium activators modification

2022-12-10 , Ooi Wan-En , Liew Yun Ming , Heah Cheng Yong , Ho Li Ngee , Mohd. Mustafa Al Bakri Abdullah , Bin Khalid M.S. , Foo Kai Loong , Ong Shee-Ween , Pei Seng T. , Hang Yong Jie , Khairunnisa Zulkifly

This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.

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Microwave-absorbing building materials: Assessing thickness and antenna separation in fly ash-ladle furnace slag one-part geopolymer

2024-06-15 , Yong-Jie H. , Heah Cheng Yong , Lee Yeng Seng , Liew Yun Ming , Mohd. Mustafa Al Bakri Abdullah , Wei-Hao L. , Pakawanit P. , Ern-Hun K. , Shee-Ween O.

This paper aims to examine the effect of thickness (20, 40, 60, 80, and 100 mm) and antenna separation (20, 40, 60, 80, and 100 mm) on microwave absorption ability of fly ash-ladle furnace slag one-part geopolymer. The one-part geopolymers exhibited a dense structure with a good compressive strength of 39.2 MPa, which satisfies the minimum requirement for structural building (>28.0 MPa). The geopolymers had good dielectric properties with a low dielectric constant and increased dielectric loss and loss tangent, subsequently contributing to the microwave absorption properties. The microwave absorption ability increased from 60.0% to >80.0% at an optimal thickness of 100.0 mm and antenna separation of 20.0 mm. The presence of calcium-silicate-hydrate (C–S–H) refined the microstructure and enhanced the microwave absorption performance. This work offered an optimal thickness and antenna separation to maximize the microwave absorption ability, which is crucial for reducing microwave interference and preventing public exposure in regions with widespread deployment of Wi-Fi and 5G networks.

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Microwave absorption function on a novel one-part binary geopolymer: Influence of frequency, ageing and mix design

2024-05-10 , Yong-Jie H. , Heah Cheng Yong , Liew Yun Ming , Mohd. Mustafa Al Bakri Abdullah , Yeng-Seng L. , Wei-Hao L. , Pakawanit P. , Shee-Ween O. , Hoe-Woon T. , Cheng-Hsuan H.

This paper presents an innovative application of a one-part geopolymer for microwave absorption. The influences of frequency, ageing time and mixing formulations on the mechanical, dielectric, and microwave-absorbing performance of the one-part binary geopolymer using fly ash and ladle furnace slag were investigated. The mixing formulations included alkali activators-to-aluminosilicate sources, sodium metasilicate-to-sodium hydroxide, and water-to-binder ratios. The results demonstrated that the dielectric constant decreased while the dielectric loss and loss tangent increased and remained constant with increasing frequency. The geopolymers have the highest dielectric values at an early age and diminish with ageing time. These resulted in the geopolymers having excellent microwave absorption (50 – 80%) at high-frequency levels and later ages. A higher water content resulted in higher porosity, reducing mechanical strength but enhancing microwave absorption. An optimal water content must be attained to achieve dual mechanical strength and microwave absorption performance.

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Interaction of silica fume on flexural properties of 10 mm-thickness geopolymers based on fly ash and ladle furnace slag under the thermal conditions

2023 , Ng Yong-Sing , Liew Yun Ming , Catleya Rojviriya , Mohd. Mustafa Al Bakri Abdullah , Heah Cheng Yong , Mohd Suhaimi Khalid , Ong Shee-Ween , Ooi Wan En , Hang Yong Jie

Studies regarding the properties of geopolymers with silica fume addition at elevated temperature exposure were rarely reported. This paper evaluates the effect of silica fume inclusion on the flexural and thermal performance of geopolymers based on fly ash (FA) and ladle furnace slag (LFS) with thickness of merely 10 mm. Fly ash/slag (FS) geopolymer was prepared by mixing FA and LFS using a weight ratio of 60:40 with an alkali activator (sodium silicate and sodium hydroxide). Silica fume (1, 2, 3, and 4 wt%) was added to prepare FSF geopolymers. The geopolymers were then subjected to the elevated temperature up to 1100 °C after 28-days of curing. Higher flexural strength of 9.1 MPa was achieved in unexposed FSF geopolymers with 3 wt% silica fume addition as compared to unexposed FS geopolymers (7.8 MPa). Flexural strength degraded with higher silica fume content of 4 wt%. Heat treatment significantly improved the flexural strength of geopolymers. Both FS and FSF3 geopolymers had increased strength of 208.9% to 24.1 MPa at 1100 °C and 192.3% to 26.6 MPa at 1000 °C, respectively as compared to the unexposed specimen. The inclusion of silica fume with extreme fineness improved the interconnectivity of the geopolymer matrix, densifying the geopolymer structure and thus enhancing the thermal resistance of geopolymers. However, the dense matrix with low flowability of FSF3 geopolymers could not sustain the high thermal stress and caused strength degradation and crack formation at a high temperature of 1100 °C. Even so, the flexural strength of 1100 °C heat-treated FSF3 geopolymer was 13.2% higher than the unexposed specimen. This demonstrated that silica fume could be incorporated in enhancing the thermal resistance and high strength achievement in geopolymers.

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