Khairunisa Muthusamy

Effect of Curing Regime on Compressive Strength of Concrete Containing Malaysian Laterite Aggregate

Concrete subjected to improper curing process would exhibit poor strength performance due to incomplete hydration process. This research investigate the effect of curing regime towards compressive strength of concrete containing Malaysian laterite aggregate (MLA) as partial coarse aggregate replacement. Concrete specimens produced using a range of laterite aggregate replacement from 0 to 50% were placed in different curing regime namely water curing, natural weather curing and air curing until the testing date. Specimens were subjected to compressive strength test in accordance to BS EN 12390 at 60 days. The results show strength of all specimens except the air cured samples increase as the curing age become longer. It was found that water curing is the most suitable for better performance of laterite concrete. The presence of water throughout the curing process is very much crucial for laterite concrete strength developement compared to normal concrete.

Acid Resistance of Oil Palm Shell Lightweight Aggregate Concrete Containing Palm Oil Fuel Ash

Concern towards reducing waste disposed by Malaysian palm oil industry, palm oil fuel ash (POFA) and oil palm shell (OPS) that poses negative impact to the environment has initiated research on producing oil palm shell lightweight aggregate concrete (OPS LWAC) containing palm oil fuel ash. The present investigation looks into the effect of palm oil fuel ash content as partial cement replacement to compressive strength and acid resistance of oil palm shell lightweight aggregate concrete. Two types of mix, plain OPS LWAC and another one containing POFA as partial cement replacement have been used in this research. Cubes of 100 x 100 x 100 (mm) were water cured for 28 days before subjected to compressive strength test and acid resistance test. The findings indicate that suitable integration of POFA content would ensure occurrence of optimum pozzolanic reaction leading to densification of concrete internal structure which increases the compressive strength and better durability to acid attack. Integration of 20% POFA successfully assist concrete to achieve the highest compressive strength and exhibit superior resistance against acid attack compared to other mixes.

Roles of Calcium in Geopolymer Containing Paper Mill Sludge Ash

High amount of calcium oxide (CaO) in source material is known to positively influence the mechanical strength of fly ash based geopolymer. This study was conducted to investigate the suitability of paper mill sludge ash (PMSA) to partially replace fly ash in geopolymer mortar based on its degree of reaction. Fly ash was activated by a combination of sodium silicate solution and 6 M sodium hydroxide solution. The mixtures were designed to replace fly ash content with PMSA at 5%, 10% and 15% (by weight of fly ash). To observe its effect on the mechanical strength, the specimens were cured in three different temperatures, which are 30°C, 60°C and 90°C for 24 hours. After 24 hours, the hardened specimens were demoulded and placed at room temperature until the testing days. Measurement on fresh geopolymer properties was conducted with setting time and flowability tests, while degree of reaction tests was conducted on the hardened specimen. Based on the results, 5% PMSA demonstrated superior degree of reaction than other mixtures, particularly at higher curing temperature.

Degree of Reaction and Alkali-Leaching of Geopolymer Containing Ca-Rich Source Material and Dipotassium Hydrogen Phosphate

Disparity of anion and cation in geopolymer framework may result in the formation of efflorescence on the surface of hardened geopolymer specimen. The existence of efflorescence would be intensified with the use of dipotassium hydrogen phosphate (K2HPO4) as a chemical retarder for geopolymer mixture. In this study, paper mill sludge ash (PMSA) was used as a Ca-rich aluminosilicate source to reduce the development of efflorescence crystals. PMSA was utilized to partially replace fly ash at 5% and 10% (by weight of fly ash). Meanwhile, K2HPO4 was used as the external agent with various proportions, which were 0.1%, 0.3%, and 0.5% (by weight of fly ash). The external agent in this study was purposed to extend the setting time and enhance the mechanical properties of geopolymer. Fly ash and PMSA (if any) were activated by reacting them with 6M sodium hydroxide and sodium silicate solution. Freshly cast specimens were cured for 24 hours in electronic oven with the temperature setting of 30°C and 90°C. They were demoulded after 24 h and kept at room temperature (28±2 °C) until the testing day. Evaluation on the setting time characteristic of fresh geopolymer mortar was conducted with Vicat test while degree of reaction was performed on the hardened specimens to measure the reaction of fly ash during geopolymerization. Based on the experimental result, the inclusion of 5% PMSA shows the greatest effect in reducing the development of efflorescence crystal and increase the degree of reaction of geopolymer system. It is presumed that PMSA has altered the geopolymerization process by activating calcium oxide precursors to form three tetrahedral structures in the framework.

Effect of unground oil palm ash as mixing ingredient towards properties of concrete

Malaysia being one of the world largest palm oil producers generates palm oil fuel ash (POFA), a by-product in increasing quantity. This material which usually disposed as solid waste causes pollution to the environment. Success in converting this waste material into benefitting product would reduce amount of waste disposed and contributes towards cleaner environment. This research explores the potential of unground oil palm ash being used as partial sand replacement in normal concrete production. Experimental work has been conducted to determine the workability, compressive strength and flexural strength of concrete when unground oil palm ash is added as partial sand replacement. A total of five mixes containing various percentage of oil palm ash, which are 0%, 5%, 10%, 15% and 20% have been prepared. All specimens were water cured until the testing date. The slump test, compressive strength test and flexural strength test was conducted. The findings show that mix produced using 10% of palm oil fuel ash exhibit higher compressive strength and flexural strength as compared to control specimen. Utilization of unground oil palm ash as partial sand replacement would be able to reduce dependency of construction industry on natural sand supply and also as one of the solution to reuse palm oil industry waste.

Properties of palm oil fuel ash cement sand brick containing pulverized cockle shell as partial sand replacement

Environmental pollution caused by the disposal of solid wastes generated from both palm oil industry and cockle shell trade has motivated researches to explore the potential of these wastes. Integrating these wastes in production of construction material is one of the way to reduce amount of waste thrown at dumping area. Thus, the present investigation investigates the performance of palm oil fuel ash (POFA) cement sand brick containing pulverized cockle shell as partial fine aggregate replacement. All mixes used contains 20% of POFA as partial cement replacement. Total of six mixes were prepared by adding a range of pulverized cockle shell that is 0%, 10%, 20%, 30%, 40% and 50% as partial sand replacement. The mixes were prepared in form of brick. All the water cured samples were tested for compressive strength and flexural strength until 28 days. Findings show that brick produced using 20% pulverized cockle shell exhibit the highest compressive strength and flexural strength also the lowest water absorption value.

Properties of Concrete Containing Unground Palm Oil Fuel Ash as Partial Sand Replacement

The growing construction industry that demands for more natural sand supply has indirectly causes the escalation of river sand mining activity. Excessive sand mining affects the water quality and habitats of aquatic life. At the same time, the continuous dumping of palm oil fuel ash, a by-product of oil palm mill causes pollution to the environment. In order to preserve the natural sand and reduce amount of palm oil fuel ash disposed as waste, the present study investigates the potential use of palm oil fuel ash in concrete production. Thus, the effect of unground palm oil fuel ash as partial sand replacement towards workability and compressive strength of concrete is discussed in this paper. A total of six mixes were used in this experimental work. Plain concrete containing 100% river sand was used as reference specimen. The rest of the mixes were prepared by integrating unground palm oil fuel ash by 2%, 4%, 6%, 8% and 10% by weight of sand. All specimens were prepared in form of cubes and subjected to water curing until the testing age. Slump test were conducted on the fresh mix to determine the concrete workability. Compressive strength test were conducted at 7, 14 and 28 days. The finding shows that addition of unground palm oil fuel ash up to 8% does not have significant effect on concrete workability. In terms of compressive strength, inclusion of 6% unground palm oil fuel ash increases the strength of concrete by approximately 13%.

Characterization of Steel Fiber Reinforced Acrylic Emulsion Polymer Modified Concrete (SFRPMC) through X-Ray Diffraction (XRD) Analysis

The results show the effect of polymer modification on the behavior of Ca (OH)2 in steel fiber reinforced concrete. The polymer modified concrete were prepared using acrylic emulsion polymer at various polymer-cement ratios; they were tested for mechanical strengths, moulded into specimens and cured. The cured specimens were subjected for compressive strength, flexural strength, splitting tensile strength and modulus of elasticity. The small specimens that moulded were subjected to X-ray diffraction (XRD). From the test results, it is concluded that formation of Ca (OH)2 in the polymer modified concrete reinforced with steel fiber is reduced possibly because of the absorption of Ca (OH)2 on polymer films formed in the concrete. The extent of reduction in the quantity of Ca (OH)2 depends upon the polymer-cement ratio, polymer type or both. Generally SFRPMC of mix 43 with 2.5% polymer-cement ratio were found to be more effective than other SFRPMC with 1.0% and 4.0% acrylic emulsion polymer in reducing the quantity of Ca (OH)2 in SFRPMC. The cement modifiers did not cause any detrimental effect on the degree of hydration as in SFRPMC therefore, does not provide a proper means for predicting their degree of hydration.

Attenuation Function Relationship for Far Field Earthquake Considered by Strike Slip Mechanism

An attenuation relationship for far field earthquakes considered by strike slip has been developed. The attenuation relationship function was develop using regression analysis. The database consisting of more than 130 peak ground accelerations from seven earthquake sources recorded by Seismology Station in Malaysia have been used to develop the relationship. This study aims to investigate the new relationship attenuation to gain exact peak ground acceleration at the location on site. Based on this study, the location is a structure located at Terengganu seaside.

POFA: A Potential Partial Cement Replacement Material in Oil Palm Shell Lightweight Aggregate Concrete

Today, the necessity of environmental awareness and enforcement is more demanding and crucial than ever before. Environmental protection encompasses not only pollution but also sustainable development and conservation of natural resources and the eco-system. As a conclusion, protection and preservation of environment is still a pressing issue. This issue on environmental preservations and sustainability all over the world has lead to innovations of new material using by-products generated from various sectors such as palm oil industry. One of the potential recycle materials from palm oil industry is palm oil fuel ash which contains siliceous compositions and reacted as pozzolans to produce a stronger and denser concrete. Palm oil fuel ash (POFA) is by-product obtained by burning of fibers, shells and empty fruit bunches as fuel in palm oil mill boilers. Apart from POFA, oil palm shell (OPS), which also from oil palm waste has been used as lightweight aggregates resulting from never ending research conducted. In this investigation, these two types of waste were collected from the same palm oil mills in Kuantan, Malaysia and were both utilized inside lightweight aggregate concrete. By incorporating POFA and OPS as partial cement and coarse aggregate replacement, lightweight aggregate concrete with 35 MPa can be produced and is also significantly higher than control OPS concrete.