Wee Kang Choong

Effects of Recycled Aggregates on Water-Cement Ratio for Concrete

Recycled aggregate differs from primary aggregate in that it constitutes of two types of materials: the primary aggregate and the attaching cement mortar. This study was conducted in order to investigate the effects on water-cement ratio for concrete cast with recycled aggregates derived from different origins (hollow blocks & structural concrete elements) and different mixed proportions of recycled aggregate contents. The outcomes of test indicate that higher water cement ratios are required for concrete cast with recycled aggregates as compare to those cast with primary aggregates. Also there appear no obvious relationships or consistencies that can be drawn among types of recycled aggregate.

Elastic Modulus of Concrete Cast with Recycled Aggregates

In view of the importance of recycled aggregates concrete with primary aim to minimise environmental impacts from construction waste, this study was conducted in order to investigate the effects of recycled aggregates on concrete elastic modulus. The outcomes indicate that type of recycled aggregates influences the development of concrete elastic modulus. In general, the use of recycled aggregates posts significant reductions in concrete elastic modulus.

Investigation into the Current Practice of Cost Estimating and the Introduction of a Standard Price Book in the Malaysia Construction Industry

Cost estimating is one of the most important areas in construction project management.Three are various ways to do cost estimating with different efficiencies and possibly with differentaccuracies. In addition it is a complicated process including various activities. Standardized pricebooks will help improve the process and accuracy of cost estimating. However there is no publishedprice book in the Malaysia construction industry. This research has investigated and identified thecurrent practice of estimating in the Malaysia construction industry together with the possibilities ofintroducing a price book to the industry. Primary methods of estimating, efficiency of the currentmethods, significance of activities related to estimating, factors affecting the accuracy of estimatingare investigated through a survey. Further the obstacles in introducing a price book have beenidentified. The survey participants agree that the government should initiate the introduction of a pricebook in the Malaysia construction industry. The outcomes of this research can be also used to improvethe competitive advantages of quantity surveyors, consulting engineers/architects and contractors inrespect to cost estimating for construction projects in Malaysia.

Waste Paper Sludge Ash (WPSA) as Binder in Solidifying Water Treatment Plant Sludge (WTPS)

Water treatment plant sludge (WTPS) is pathogen and heavy metals that can harm human health and the environment. As strict regulation had been implemented, WTPS is advised and must be treated before the waste is transported to landfill. Therefore, this research is conducted to solidify WTPS with an alternative waste material. The waste material so called as waste paper sludge ash (WPSA) was chosen as binder to be used to solidify WTPS. WPSA is a waste that is produced in bulk at the recycled paper factories. Somehow, its potentiality, especially as cement replacement materials is unknown. The objective of this research is to investigate the possibility of using WPSA as an alternative replacement material of cement in solidifying the WTPS. WPSA was used in proportions of 10, 20, 30, and 40 % as cement replacement by volume along with WTPS in fixed quantity. An additional mix without WPSA solidifying WTPS is also prepared. The effectiveness of WPSA in solidifying WTPS was determined based on the compressive strength achieved on 1, 3, 7, and 28 days of curing. High replacement amount of WPSA with at least 0.34 N/mm2 compressive strength will be selected as the best mix. Based on results obtained, the compressive strength of solidified WTPS increased with increasing curing days for all mix types. The smallest particle size and highest surface area of WPSA had contributed to the condition. Although, the compressive strength of solidified WTPS decreases with increasing WPSA percentage replacement. In addition, WPSA used in this research was a non-pozzolanic material with very porous surface area and irregular shape. In conclusion, a mix of 40 % WPSA labeled as W5 is a more sustainable mix binder in solidifying WTPS. Although, W2 with 10 % of WPSA substitution had passed the landfill acceptable limit at 0.34 N/mm2.

Effects of recycled aggregates on concrete strengths

Abstract With the primary aim to minimise environmental impacts from construction waste, this study was conducted in order to investigate the effects of recycled aggregates on concrete compressive and flexural tensile strengths. The outcomes indicate that recycled aggregates caused significant reductions in the attainment of concrete compressive strength (up to 21%) and flexural tensile strength (up to 39%) as aggregates replacement increases to 75%.

The Effects of Temperature on the Stiffness Modulus of Dense Graded Asphalt Mixtures

This study aimed to investigate the effect of temperature on stiffness modulus of asphaltic concrete. The asphaltic concrete mixture were prepared based on Marshall Mix Design method using two different types of bitumen, the 80/100 penetration grade bitumen (80/100 PGB) and Styrene-Butadiene-Styrene (SBS), both with five percent bitumen content. Indirect Tensile Stiffness Modulus (ITSM) test of 1000 N loading was then performed at three different temperatures (25 °C, 30 °C and 40 °C). The results showed that stiffness modulus decreases with increases in temperature for both 80/100 PGB and SBS, which shows the important role of temperature to stiffness modulus of asphaltic concrete. Also, the results showed a higher stiffness modulus for SBS mixtures compare to that of 80/100 PGB mixtures.

Benchmarking the Industrial Expectations of Civil Engineering Students through Internship Placements

In view of the importance of undergraduate students professional attributes development in higher education, this study was conducted in order to investigate the effectiveness and relevancy of the two years undergraduate studies pre-requisite for industrial internships. The outcomes indicate that the two years conducing learning environments provided have been effective in stimulating cognitive learning and motivate students for ethical practice that fulfilled the industrial expectations.

Application of Risk Significance Index Score to Construction Projects in Malaysia

Risk management is one of the most important areas in project management particularly in the construction industry. However it is not possible to analyze all of the potential risks as it will require too much time and effort. Therefore in order to identify and analyze the significant risks, the risks should be categorized and ranked. This research applied the concept of risk significance index score to construction projects in Malaysia. A comprehensive list of 40-potential risks has been developed through literature review and an interview survey. A questionnaire survey was conducted to produce project risk significance index score for the risks. The ranks of the risks have been identified and solutions for the significant risks have been produced through interviews. This research proves the practical use of risk significance index score for construction projects in Malaysia.

Ethical Directions and Cultural Dimensions of Construction Professionals in Malaysia: With a Framework of Ethical Decision Making

Corporate ethics and business ethics are becoming new requirements for a successful business in the 21st century. This trend continues to be strengthened throughout the industries and the construction industry cannot be exceptional. This research provides a practical framework of ethical decision making for construction together with the perceptions of construction professionals in respect to ethics and culture. A project factor approach is incorporated in the framework to reflect the unique feature of construction. The framework is based on Agent (virtue ethics) - Action (deontology) Results (consequentialism) model and the stakeholder concept of construction projects. The framework also intends to identify the ethical directions either mean-oriented or end-oriented. The effectiveness of the framework has been proved through a survey with construction professionals in Malaysia. The survey also includes cultural dimensions as ethic is a subset of culture. The outcomes of the survey shows that the construction professional in Malaysia are slightly more mean-oriented than end-oriented, and their cultural dimensions are more power oriented (PDI), more individualistic (IDV) and more masculine (MAS) compared to the Malaysia national level cultural dimensions.