The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mohd Mustafa Al Bakri Abdullah - One of the best experts on this subject based on the ideXlab platform.
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effect of fly ash Alkaline Activator ratio on fly ash geopolymer artificial aggregate
AIP Conference Proceedings, 2018Co-Authors: Alida Abdullah, Mohd Mustafa Al Bakri Abdullah, K Hussin, Subaer Junaidi, Muhammad Faheem Mohd TahirAbstract:This research was conducted to study the effect of fly ash on Alkaline Activator ratio to the fly ash geopolymer artificial aggregate. The raw material used is fly ash, sodium silicate and sodium hydroxide. This research involves four different ratio of mix design which is 2.0, 2.5, 3.0 and 3.5 while ratio of NaOH/NaSi2O3 is constant at 2.5. In this study, the molarity of NaOH is fix at 12M. The characterization of fly ash was done by X-Ray Fluorescence (XRF). The properties of fly ash geopolymer artificial aggregate then characterized by Aggregate Impact Value (AIV), and its microstructure been observed by Scanning Electron Microscope (SEM). Results show that, the sample with Fly Ash/Alkaline Activator 3.0 give the lowest percentage of AIV (19.6%) which denotes a high performance of aggregate in concrete field and also contribute to high performance of concrete while ratio 2.0 gives the highest percentage of AIV (25.19%). The tested results indicated that the significant potential of fly ash geopolymer aggregate as an alternative artificial aggregate in construction materials field.
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strength and density of geopolymer mortar cured at ambient temperature for use as repair material
IOP Conference Series: Materials Science and Engineering, 2016Co-Authors: A Warid Z Wazien, Mohd Mustafa Al Bakri Abdullah, Rafiza Abd Razak, M Mohd Remy A Z Rozainy, Muhammad Faheem Mohd TahirAbstract:Geopolymers produced by synthesizing aluminosilicate source materials with an Alkaline Activator solution promised an excellent properties akin to the existing construction material. This study focused on the effect of various binder to sand ratio on geopolymer mortar properties. Mix design of geopolymer mortar was produced using NaOH concentration of 12 molars, ratio of fly ash/Alkaline Activator and ratio Na2SiO3/NaOH of 2.0 and 2.5 respectively. Samples subsequently ware cured at ambient temperature. The properties of geopolymer mortar were analysed in term of compressive strength and density at different period which are on the 3rd and 7th day of curing. Experimental results revealed that the addition of sand slightly increase the compressive strength of geopolymer. The optimum compressive strength obtained was up to 31.39 MPa on the 7th day. The density of geopolymer mortar was in the range between 2.0 g/cm3 to 2.23 g/cm3. Based on this findings, the special properties promoted by geopolymer mortar display high potential to be implemented in the field of concrete patch repair.
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flood mud as geopolymer precursor materials effect of flood mud Alkaline Activator and na2sio3 naoh ratios on compressive strength
Applied Mechanics and Materials, 2015Co-Authors: Mohd Mustafa Al Bakri Abdullah, Kamarudin Hussin, Che Mohd Ruzaidi Ghazali, Muhammad Faheem Mohd Tahir, Liew Yun Ming, Alida AbdullahAbstract:This paper investigates the potential and suitability of flood mud to be used in geopolymer technique as construction materials. Flood mud was collected from Kelantan, Malaysia and crushed and sieved into powder form. Then, it was mixed with Alkaline Activator solution (mixture of NaOH and Na2SiO3 solutions) followed by curing process to produce flood mud geopolymers. In addition, the effect of varying solids/liquid (S/L) and Na2SiO3/NaOH ratios on the compressive strength of flood mud geopolymers were also investigated. The result showed that flood mud can be potentially used as precursor materials for geopolymer formation with favorable strength. Optimum compressive strength (24.6 MPa) of geopolymers based on flood mud was obtained at S/L = 1.25 and Na2SiO3/NaOH = 1.0.
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the electrical resistivity of geopolymer paste by using wenner four probe method
Key Engineering Materials, 2015Co-Authors: Farah Farhana Zainal, Shaiful Rizam, Mohammad Tamizi Selimin, Azmi Rahmat, Mohd Mustafa Al Bakri Abdullah, Kamarudin Hussin, Andrei Victor SanduAbstract:This paper presents an experimental study of the electrical resistivity of geopolymer paste by using a non-destructive test employing Wenner four probe method. Geopolymer is produced from a combination mixture of aluminosilicate materials which is rich in Si and Al such as fly ash with an Alkaline Activator. Geopolymer paste in this study was made from a mixture of class F fly ash, sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) solution. An Alkaline Activator was prepared 24 hrs prior to use with the ratio mixture of Na2SiO3/NaOH being 2.5. Then, the prepared Alkaline Activator was mixed with the fly ash for about 30 minutes. After that, the mixture was placed in a 100 mm x 103 mm x 495 mm mould. After 24 hrs, the sample was taken out from the mould and cured at 60°C in the oven for 24 hrs. The sample was then tested after 7, 14 and 28 days. The current applied in this study was from 0.01 mA to 1.00 mA and the electrode spacing used were 0.02 m, 0.04 m, 0.06 m, 0.08 m and 0.10 m. The results showed that the geopolymer paste after 28 days with the current of 0.01 mA and 0.10 m electrode spacing showed the highest resistivity with 61575 Ω.m while the geopolymer paste after 7 days with 0.95 mA and 0.02 m electrode spacing showed the lowest resistivity with 537 Ω.m. Hence, the corrosion rate of geopolymer paste in this study was negligible and if occur, was very low.
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optimization of naoh molarity lusi mud Alkaline Activator and na2sio3 naoh ratio to produce lightweight aggregate based geopolymer
International Journal of Molecular Sciences, 2015Co-Authors: Rafiza Abdul Razak, Mohd Mustafa Al Bakri Abdullah, Kamarudin Hussin, Khairul Nizar Ismail, Djwantoro Hardjito, Zarina YahyaAbstract:This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and Alkaline Activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline Activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline Activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced.
Cengiz Duran Atis - One of the best experts on this subject based on the ideXlab platform.
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alkali activation of mortars containing different replacement levels of ground granulated blast furnace slag
Construction and Building Materials, 2012Co-Authors: Cahit Bilim, Cengiz Duran AtisAbstract:Abstract The aim of the present study is to investigate some properties of alkali-activated mortars containing slag at different replacement levels. Ground granulated blast furnace slag was used at 0%, 20%, 40%, 60%, 80% and 100% replacement by weight of cement, and liquid sodium silicate having three different Na dosages was chosen as the Alkaline Activator. In this research, carbonation resistance measurements and compressive and flexural strength tests were performed on the mortar specimens with size of 40 × 40 × 160 mm. The findings obtained from the tests showed that carbonation depth values of the mortars decreased with the increase of Activator dosage. Additionally, compressive and flexural strength values increased with the increase in Activator concentration and slag replacement level. Portland cement/slag mortars activated by liquid sodium silicate exhibited lower strength than the slag alone activated by the same Activator.
Manpreet Kaur - One of the best experts on this subject based on the ideXlab platform.
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compressive strength of rice husk ash based geopolymer the effect of Alkaline Activator
Construction and Building Materials, 2018Co-Authors: Kamaldeep Kaur, Jaspal Singh, Manpreet KaurAbstract:Abstract In this paper, the effect of alkali Activator to binder (AAB) ratio and molarity of Alkaline Activator on the rice husk ash based geopolymer were investigated. Compressive strength has been determined on 70.6 × 70.6 × 70.6 mm specimens by varying AAB ratio from 0.5 to 0.7 and molarity of alkali Activator solution from 12 M to 16 M. The microstructure was also examined using scanning electron microscope (SEM). Experimental results revealed that the maximum compressive strength is obtained up to 39.95 N/mm2 after 28 days. It has been observed that compressive strength is directly proportional to both AAB ratio and molarity of alkali Activator solution. With increasing the molarity, microstructure become quite dense, this may be attributed to high degree of geopolymerisation.
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synthesis of fly ash based geopolymer mortar considering different concentrations and combinations of Alkaline Activator solution
Ceramics International, 2018Co-Authors: Mandeep Kaur, Jaspal Singh, Manpreet KaurAbstract:Abstract Geopolymerisation is a process that can transform alumina and silica rich waste materials into valuable binding materials, having excellent mechanical properties. The present experimental study shed a light on the variation in compressive strength of fly ash based geopolymer mortar by varying the molarity of sodium hydroxide as 12 M, 14 M, 16 M and accompanying by sodium silicate (Na 2 SIO 3 ) in 2:1 (Na 2 SIO 3 / NaOH) with same molarities. All the geopolymer mixes were oven cured at 80 °C for 24 h and after that kept at room temperature up to the time of testing. The compressive strength was checked subsequently at the ages of 3, 7, 14 and 28 days. The experimental results reveal that the addition of sodium silicate enhances the strength development in geopolymer mortar. The ultimate compressive strength of 40.42 MPa was obtained by incorporating sodium silicate along with 16 M concentrated sodium hydroxide. Furthermore, increasing trend of the compressive strength was found with increasing molar concentration of sodium hydroxide and curing period.
H. Kamarudin - One of the best experts on this subject based on the ideXlab platform.
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Correlation between Na2SiO3/NaOH Ratio and Fly Ash/Alkaline Activator Ratio to the Strength of Geopolymer
2016Co-Authors: A. M. Mustafa, Al Bakri, H. Kamarudin, Khairul I. Nizar, M. Bnhussain, Y. Zarina, A. R. RafizaAbstract:strength Abstract. Geopolymer requires an Alkaline Activator to induce it pozzolanic property and to accelerate the geopolymerisation process. The geopolymerisation process occurs due to the mixing of fly ash, sodium silicate and sodium hydroxide as the Alkaline Activator, which produces aluminosilicate gel that acts as a binder. As such, the ratios of fly ash to Alkaline Activator and Na2SiO3/NaOH play an important role in obtaining desirable compressive strength; the concentration of NaOH used in this study was 12 M. Different ratios of fly ash to Alkaline Activator (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) and Na2SiO3/NaOH (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) were investigated in order to determine the maximum compressive strength. The Alkaline Activator was mixed with fly ash with different ratio as mentioned above and the samples were cured at 70°C for 24 hours and tested on the seventh day. The maximum compressive strength was obtained when the ratios of fly ash to Alkaline Activator and Na2SiO3/NaOH were 2.0 and 2.5 with compressive strength 73.86 MPa
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effect of naoh concentration on microstructure of boiler ash based geopolymer
Materials Science Forum, 2014Co-Authors: Zarina Yahya, H. Kamarudin, Khairul I. Nizar, Abdullah Mohd Mustafa Al Bakri, Abdul Rahim Abdul RazakAbstract:Boiler ash is one of the waste material from palm oil processing industry and it was widely available. The role of Alkaline Activator in geopolymer is important for its mechanical properties. NaOH and sodium silicate solution was used as Alkaline Activator. In order to investigate effect of NaOH concentration on microstructure of boiler ash based geopolymer 6 different NaOH concentration (6M, 8M, 10M, 12M, 14M, 16M) were used. The boiler ash based geopolymer samples were cured in oven at temperature 80 °C for 24 hr. The compressive strength of geopolymer samples at 7 days showed that 14M obtained the maximum strength (13.9 MPa). This result was supported with SEM analysis were the 14M geopolymer sample showed more dense geopolymer matrix compared to others.
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the relationship of na2sio3 naoh ratio kaolin Alkaline Activator ratio and sand kaolin ratio to the strength of kaolin based non load bearing geopolymer brick
International Review of Mechanical Engineering-IREME, 2013Co-Authors: M Muhammad T Faheem, A Mustafa Al M Bakri, H. Kamarudin, C M Ruzaidi, Mohammed Binhussain, A M IzzatAbstract:The strength of geopolymer depends on the nature of source materials. For example, geopolymer produced with calcined source material such as calcined kaolin, fly ash, ground granulated blastfurnace slag (GGBS) and others produce a higher compressive strength compared to geopolymer produced with non-calcined source material such as kaolin. This paper studied the effect of various ratios of Na2SiO3/NaOH ratio, kaolin/Alkaline Activator ratio and sand/kaolin ratio to the strength of clay - based geopolymer brick. The samples had been tested to determine their compressive strength, density, and water absorption properties. Compression tests were conducted at seventh day of testing of all specimens. Tests were carried out on standard size of geopolymer brick according to British Standard (BS 3921).
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design processing and characterization of fly ash based geopolymers for lightweight concrete application
2013Co-Authors: A. M. Mustafa, Andrei Victor Sandu, H. Kamarudin, Y. Zarina, Ismail Khairul Nizar, Mohamed Binhussain, A. R. RafizaAbstract:The mix design of geopolymers plays important role in obtaining desirable compressive strength. Optimum mix design of geopolymers can be applied for application, such as lightweight concrete. In order to determine the maximum compressive strength for lightweight concrete production, fly ash geopolymers were produced with various ratios of fly ash/Alkaline Activator (0.5 - 3.0), Na 2 SiO 3 solution/ NaOH solution (0.5 - 3.0) and 12 M of NaOH solution. The geopolymer materials were mixed and cured at 70°C for 24 h and tested on 7 days. Maximum compressive strength was obtained when the ratios of fly ash/Alkaline Activator and Na 2 SiO 3 solution/NaOH solution were 2.0 and 2.5, respectively. The characterization and morphology of geopolymers were performed by using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). It was clearly shown that the best mix design of geopolymers produced denser matrix and less unreacted fly ash compared to other samples.
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study on solids to liquid and Alkaline Activator ratios on kaolin based geopolymers
Construction and Building Materials, 2012Co-Authors: C Y Heah, A Mustafa Al M Bakri, H. Kamarudin, Khairul I. Nizar, M. Bnhussain, C M Ruzaidi, Musa Luqman, Y M LiewAbstract:Kaolin and alkali Activator were mixed with the solids-to-liquid ratios in range of 0.60–1.20 (Al2O3/Na2O molar ratio of 0.63–1.27). Sodium silicate and sodium hydroxide ranged between 0.16 and 0.36 (SiO2/Na2O molar ratio of 3.19–3.67) were mixed together to prepare alkali Activator. The results concluded that compressive strength was affected by both S/L and Na2SiO3/NaOH ratios and strength increased with ageing day. Both these ratio also influenced the workability of the mixes. Besides, the kaolin geopolymers showed good volume stability in water. Compressive strength was highest at S/L and Na2SiO3/NaOH ratios of 1.00 and 0.32, respectively. In term of molar ratios, optimum was achieved at Al2O3/Na2O of 1.09 and SiO2/Na2O molar ratios of 3.58. Microstructures showed that kaolin particles were slightly activated with large part of unreacted raw materials remained in the system. Geopolymer sample reduced in peak intensities over time as presented by XRD analysis and the presence of crystalline peaks in the kaolin geopolymers was Zeolite X. FTIR analysis showed the presence of geopolymer bonding increased over age. In overall, kaolin geopolymers does not undergo complete geopolymerization and showed slow strength development. Vast research works have to be carried out to further improve the properties of kaolin geopolymers.
Francisca Puertas - One of the best experts on this subject based on the ideXlab platform.
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Alkali-activated slag concrete: Fresh and hardened behaviour
Cement and Concrete Composites, 2018Co-Authors: Francisca Puertas, B. González-fonteboa, I. González-taboada, G. Rojo, Manuel Torres-carrasco, M.m. Alonso, F. Martínez-abellaAbstract:The behaviour of fresh and hardened alkali-activated slag (AAS) and OPC concretes was compared and the effect of mixing time assessed. OPC and AAS concrete slump and rheological results proved to differ, particularly when the slag was activated with waterglass (WG). The nature of the Alkaline Activator was the key determinant in AAS concrete rheology. Bingham models afforded a good fit to all the OPC and AAS concretes. In OPC and NaOH-activated AAS concretes, longer mixing had an adverse effect on rheology while improving hardened performance only slightly. In WG-AAS concrete, longer mixing times, improved mechanical properties and also rheological behaviour was enhanced, in which those conditions were required to break down the microstructure. Longer mixing raised thixotropy in OPC and NaOH-activated AAS concretes, but lowered the value of this parameter in waterglass-activated slag concrete.
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pore solution in alkali activated slag cement pastes relation to the composition and structure of calcium silicate hydrate
Cement and Concrete Research, 2004Co-Authors: Francisca Puertas, Ana Fernandezjimenez, Maria Teresa BlancovarelaAbstract:Abstract In this work, the relationship between the composition of pore solution in alkali-activated slag cement (AAS) pastes activated with different Alkaline Activator, and the composition and structure of the main reaction products, has been studied. Pore solution was extracted from hardened AAS pastes. The analysis of the liquids was performed through different techniques: Na, Mg and Al by atomic absorption (AA), Ca ions by ionic chromatography (IC) and Si by colorimetry; pH was also determined. The solid phases were analysed by XRD, FTIR, solid-state 29 Si and 27 Al NMR and BSE/EDX. The most significant changes in the ionic composition of the pore solution of the AAS pastes activated with waterglass take place between 3 and 24 h of reaction. These changes are due to the decrease of the Na content and mainly to the Si content. Results of 29 Si MAS NMR and FTIR confirm that the activation process takes place with more intensity after 3 h (although at this age, Q 2 units already exist). The pore solution of the AAS pastes activated with NaOH shows a different evolution to this of pastes activated with waterglass. The decrease of Na and Si contents progresses with time. The nature of the Alkaline Activator influences the structure and composition of the calcium silicate hydrate formed as a consequence of the Alkaline activation of the slag. The characteristic of calcium silicate hydrate in AAS pastes activated with waterglass is characterised by a low structural order with a low Ca/Si ratio. Besides, in this paste, Q 3 units are detected. The calcium silicate hydrate formed in the pastes activated with NaOH has a higher structural order (higher crystallinity) and contains more Al in its structure and a higher Ca/Si ratio than those obtained with waterglass.
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Structure of calcium silicate hydrates formed in Alkaline-activated slag: Influence of the type of Alkaline Activator
Journal of the American Ceramic Society, 2003Co-Authors: Ana Fernández-jiménez, Isabel Sobrados, Francisca Puertas, Jesús SanzAbstract:The influence of the Alkaline Activator (NaOH, waterglass, or Na 2 CO 3 ) on the structure of the hydrated calcium silicate formed in alkali-activated slag (AAS) cement pastes has been investigated by FTIR, 29 Si and 27 Al magic-angle scattering nuclear magnetic resonance, and TEM/EDX techniques. In all cases, the main product formed after 7 d of activation, with Activators giving an Na 2 O concentration of 4%, is a semicrystalline calcium silicate hydrate with a dreierkette-type anion. In these structures, linear finite chains of silicate tetrahedra (Q 2 units) are linked to central Ca-O layers, and tetrahedral aluminum occupies bridging positions in the chains. The main chain length and the amount of aluminum incorporated in the tetrahedral chains depend on the Activator used. The detection of Q 3 silicon entities in Alkaline-activated slags is discussed in relation to the possible formation of cross-linked structures that may be responsible for increased flexural and compressive strengths in AAS mortars.