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Articles by Mahyuddin Ramli
Total Records ( 8 ) for Mahyuddin Ramli
  Kwan Wai Hoe and Mahyuddin Ramli
  Problem statement: Production of concrete is always deal with inconsistency. Sources of variation like materials from different geographical basis, mix design method, fineness of aggregates and so on will attribute to different level of achievement of the concrete. Even though researcher had verified that higher fineness modulus of sand would yield better performance for the concrete, but so far there have been scarce amount of paper reported on the mix design method adopting high fineness modulus of sand. Approach: This study discussed the revolution of design mix proportion towards achieving high strength with considerably cement content using local availably constituent materials. A total of 15 mixes was casted till to the high strength at more than 65 MPa was achieved. The compressive strength and workability of each mixes were presented. The method of mixture proportioning was begun with British Department Of Environment (DOE) method. Then, rational design method of achieving high strength concrete was developed. Results: At the end of experimental program, it was found that DOE method was not suitable to apply in designing high strength concrete. 12% was the optimum level of replacement of the total binder content by silica fume. Further increase of total binder content without adjustment to the amount of aggregate content has decreased the strength achievement of the concrete. Very coarse fine aggregate with fineness modulus 3.98 increased the compressive strength of the concrete in large extent. The increased of superplasticiser from 2.0% to 2.5% has decreased the compressive strength of the concrete. Conclusion: The rational mix design approach was developed. A Grade 70 concrete can be produced with moderate level of cement content by this approach.
  Mahyuddin Ramli and Kwan Wai Hoe
  Problem statement: High Strength Concrete (HSC) normally content high cementitous amount and low water binder ratio. However, these would cause substantial volume changes to the concrete and therefore affected the strength development. In addition, the brittleness of HSC was increased when silica fume used as partial cement replacement to achieve high strength. Approach: This study discussed the effects of incorporated short discrete Coconut Fibers (CF), Barchip Fibers (BF) and Glass Fibers (GF) into HSC to enhance the performance of concrete while kept the binder content at moderate level. Additional specialty to this HSC was casted with very coarse sand with fineness modulus of 3.98. A total of thirteen mixes were casted and tested for slump, density, compressive strength, flexural strength and ultrasonic pulse velocity in accordance with British Standards. Results: The slump was slightly reduced by the short discrete fibers. All of the fibrous specimens had lower density than control. However, the compressive strength of the HSC had increased from 71.8-79.0 MPa using 1.8% of BF, while flexural strength had increased from 5.21-6.50 MPa. All specimens showed that ultrasonic velocity higher than 4.28 km sec-1. Conclusion/Recommendations: In short, combination of incorporated short discrete fibers and applied very coarse sand to produce HSC showed very satisfying results and improvements. Further assessment on durability and impact resistivity will be verified in the coming research.
  Cheah Chee Ban and Mahyuddin Ramli
  Problem statement: Numerous data and information on pozzolanic reaction and microfiller properties of silica fume were derived from laboratory investigation on silica fume in undensified form. Currently, due to low bulk density of undensified silica fume which poses problem in transportation and handling of the material, silica fume are commercially supplied in densified form. Densification process used to increase bulk density of fresh silica fume has resulted in agglomeration of the silica fume particles hence altering its effective particle size and distribution which may affect its hydration and microfiller properties. However, very few studies have been performed to study hydration properties of cementitious mixtures containing Densified Silica Fume (DSF) as supplementary binder. Approach: Characterization of physical and chemical properties of DSF was performed. Compressive strength of high performance mortar mixtures containing DSF as partial cement replacement material at various level of replacement ranging between 0-25% was assessed. Water absorption and intrinsic air permeability of hardened mortars was evaluated at the age of 28 days. Results: Incorporation of DSF at replacement level up to 25% produced mortar with higher 28 days compressive strength as compared to the control mortars. Reduction in 28 day water absorption and intrinsic air permeability of mortar was observed for mortar containing DSF up to 15% by weight of binder. Conclusion: DSF was determined to have large median particle size of 28.21 μm and high amorphous silica content. Incorporation of DSF in mortar increases water demand of mix to achieve constant workability. Optimum level of cement replacement using DSF to ensure best compressive strength performance was found to be 7.5% by total weight of binder.
  Mahyuddin Ramli and Eethar Thanoon Dawood
  Problem statement: Researches has been conducted worldwide on a large number of natural or artificial lightweight aggregates. In spite of many of the researches of using natural fibers show considerable promise, the use of natural fibers to improve the properties of lightweight concrete still required to be a subject of further research and investigation. Approach: This experimental investigation was carried out to study the properties of lightweight crushed brick concrete containing palm fiber of different volume fractions. An experimental programme was planned in which the tests such as density, compressive strength and flexural strength were conducted to investigate the properties of lightweight crushed brick concrete reinforced by palm fiber. The specimen incorporated different volume fractions of palm fiber, i.e., 0, 0.2, 0.4, 0.6, 0.8 and 1.0%. Results: Tests results showed that the use of this fiber slightly increases the density of lightweight concrete. The use of 0.8% of palm fiber increases the compressive strength and flexural strength by about 13.4 and 16.1% respectively. Conclusion: The results indicated that the use of palm fiber with lightweight crushed brick concrete enhances the mechanical properties of the concrete and the optimization of the palm fiber fractions is required to get the best performance.
  Cheah Chee Ban and Mahyuddin Ramli
  Problem statement: Mortar mix is a major construction material in fabrication of ferrocement structural elements. However, there have been scarce amount of technical data available on suitable mix proportion to achieve structural grade mortar with specific strength requirement and adequate level of workability for proper placement into construction formwork. Moreover, current practice in ferrocement construction work which uses mortar mix with cement: sand ratio ranging between 1:1.5 to 1:2 incurs high requirement of cement yet producing mix with suboptimum level of compressive strength. Approach: An experimental investigation was carried out to evaluate workability and compressive strength properties of structural grade mortar mixes with various cement: sand ratios ranging from 1:2.0-1:2.75 and varying water/binder ratio between 0.35 and 0.50. Throughout the laboratory investigation, a total of 28 batches of mortar mixes with various mix proportion were designed, cast and tested in accordance to relevant standards of practice prescribed by British Standard Institute (BSI) and American Society of Testing Material (ASTM). Results: At the end of the laboratory investigation program, high performance mortar mix with compressive strength exceeding 55 MPa and slump level within 50-90 mm which is suitable for heavy duty ferrocement construction work was successfully developed. Moreover, data on mix proportion for several other grades of mortar mixes ranging from grade 35 to grade 55 were also derived. Conclusion: It was found that optimum cement: Sand ratio of structural mortar is 1:2.25. With the use of this cement: Sand ratio in the production of structural grade mortar mix in fabrication of ferrocement structural elements, consumption of cement binder will be economized hence resulting in potential savings in term of material and production cost of mortar mix in the construction industry. Besides, it was also observed that strengths of mortar mixes do not vary linearly with cement content of the mix.
  Ahmad Sanusi Hassan and Mahyuddin Ramli
  Problem statement: It was the aim of the study to analyze the level of performance of natural air ventilation with a case study of the traditional Malay house in Penang, Malaysia. This study provided information on the architectural design in relation to natural air ventilation. It promoted passive design in contrast to most housing design which has poor natural air ventilation because the design was orientated to energy consumption that slightly more than one third of the electric energy was used for heating, ventilating and air conditioning systems. Approach: This analysis used quantitative method which measured temperature, humidity and wind speed of the traditional house. The result indicated the level of performance of cross air ventilation and stack effect. Results: The analysis showed that the traditional house has a design integrated with natural air ventilation system. The indoor house temperature and relative humidity had slightly lower than its outdoor area. However, the indoor area had lower wind speed level than the outdoor area. Conclusion: The study showed that maximum openings on the building walls created high air intakes outside the house to give poor performance of stack effect. The design had more emphasis to cross air ventilation.
  Mahyuddin Ramli and Eethar Thanon Dawood
  In recent years, there have been growing interests in utilizing some different fibers in concrete mixes for gaining some advantages from the concept of hybridization of fibers. There are many studies of using mono-fibers such as steel, glass, polypropylene fibers, among others. This review is a trial of showing some highlights for the inclusion of hybrid fibers in concrete mixes and their effects on the different mechanical properties of concrete.
  Eethar Thanon Dawood and Mahyuddin Ramli
  The use of fibers in concrete or mortar is well known for their potential to enhance the flexural toughness, the energy dissipation and the impact resistance for many structural applications especially in building repairs and other Civil Engineering works. The use of fibers in flowable concrete provides great advantages in arresting cracks and enhancing the flexural rigidity of the composite material. Hence, this study investigates the procedure of tests required to determine the conductivity of the repair material by adoption of some combined systems of repair materials with concrete and the bond action of this repair material (Flowable high strength system).
 
 
 
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