Raha Rahman

Extent of highway travel time differentials resulting from rainfall intensities

Travel time on a roadway segment is what most road users are concerned about. It is a useful guide for measuring road users’ perception of the quality of roadway service. Rainfall affects traffic flows by reducing drivers’ visibility and road surface friction among others. These reductions have profound impacts on travel time. The aim of the paper is to determine the impact of rainfall intensities (slight, moderate and heavy) on travel time. The impact study was carried out at locations along Terengganu East Coast Highway 5, between November 2010 and February 2011. Based on the hypothesis that rainfall intensity has effect on travel time, a ‘with-and-without rainfall impact study for both directions of a single carriageway was conducted. Volume, speed, headway, gaps and types of vehicles collected by way of automatic traffic counter continuously for three months estimated and compared. Rainfall data were collected and supplemented with data supplied by the Malaysian Hydrology Department. Results show that light and moderate rainfall will cause a travel time increase of about 0.43 and 0.54 minutes per kilometer by respectively; whereas heavy rainfall will account for travel time increase of 0.74 minutes per kilometer. It also shows that traffic kinematics and shockwave propagations at the onset of rainfall can also be called to account for travel time differentials. The paper concluded that rainfalls irrespective of their intensities have significant impact on roadway travel time.

Influence of Ageing Process on Rheological Characteristic of Waste Natural Rubber Latex Modified Bitumen

occurs during the modification and ageing process. The ageing process does consequences in road deterioration; however, it is also benefits in determination of optimum properties during bitumen modification process. Thus, this study was conducted to evaluate the changes of bitumen (unmodified and modified) properties as it was exposed to artificial ageing process. In order to achieve the objective, base bitumen (PEN 60/70) was modified with waste natural rubber (NR) latex. Subsequently, the modified bitumen was subjected to a laboratory ageing process by the aided of rolling thin oven film (RTFOT) and pressure ageing vessel (PAV). Its rheological characteristic was evaluate using dynamic shear rheometer (DSR). It was found that, associating waste NR latex with bitumen improved its properties during short term and long term ageing, indicated by G*/sin δ and G*.sin δ. The performanc

A review on seashells ash as partial cement replacement

This review paper emphasis on various sea shells ash such as cockle, clam, oyster, mollusc, periwinkle, snail, and green mussel shell ash as partial cement replacement and its objective is to create sustainable environment and reduce problems of global warming. Cement production give huge impact to environment in every stage of its production. These include air pollution in form of dust and, gases, sound and vibration during quarry crushing and milling. One of the solutions to solve this problem is by using modified cement. The modified cement is a cementitious material that meets or exceeds the Portland cement performance by combining and optimizes the recycle and wasted materials. This will indirectly reduce the use of raw materials and then, become a sustain construction materials. Therefore, the replacement of cement in concrete by various sea shell ash may create tremendous saving of energy and also leads to important environmental benefits. This study includes previous investigation done on the properties of chemical and mechanical such as specific gravity, chemical composition, compressive strength, tensile strength and flexural strength of concrete produced using partial replacement of cement by seashells ash. Results show that the optimum percentage of seashells as cement replacement is between 4 – 5%.

The comparison of properties and cost of material use of natural rubber and sand in manufacturing cement mortar for construction sub-base layer

The main issue related to this research was to examine the feasibility of natural rubber SMR 20 in the manufacturing of cement mortar for sub-base layer construction. Subbase layers have certain functions that need to be fulfilled in order to assure strong and adequate permeability of pavement performance. In a pavement structure, sub-base is below the base and serves as the foundation for the overall pavement structure, transmitting traffic loads to the sub-grade and providing drainage. Based on this research, the natural rubber, SMR 20 was with the percentages of 0%, 5%, 10% and 15% to mix with sand in the manufacture of the cement mortar. This research describes some of the properties and cost of the materials for the natural rubber and sand in cement mortar manufacturing by laboratory testing. Effects of the natural rubber replacement on mechanical properties of mortar were investigated by laboratory testing such as compressive strength test and density. This study obtained the 5% of natural rubber replaced in sand can achieved the strength of normal mortar after 7 days and 28 days. The strength of cement mortar depends on the density of cement mortar. According to the cost of both materials, sand shows the lower cost in material for the cement mortar manufacturing than the uses of natural rubber. Thus, the convectional cement mortar which used sand need lower cost than the modified rubber cement mortar and the most economical to apply in industrial. As conclusion, the percentage of 5% natural rubber in the cement mortar would have the same with normal cement mortar in terms of the strength. However, in terms of the cost of the construction, it will increase higher than cost of normal cement mortar production. So that, this modified cement mortar is not economical for the road sub-base construction.

The optimum content of rubber ash in concrete: flexural strength

Discarded scrap tyres have become one of the major environmental problems nowadays. Several studies have been carried out to reuse waste tires as an additive or sand replacement in concrete with appropriate percentages of tire rubber, called as rubberized concrete to solve this problem. The main objectives of this study are to investigate the flexural strength performance of concrete when adding the rubber ash and also to analyse the optimum content of rubber ash in concrete prisms. The performance total of 30 number of concrete prisms in size of 100mm x 100mm x 500 mm were investigated, by partially replacement of rubber ash with percentage of 0%, 3%, 5%, 7% and 9% from the volume of the sand. The flexural strength is increased when percentage of rubber ash is added 3% from control concrete prism, RA 0 for both concrete prism age, 7 days and 28 days with value 1.21% and 0.976% respectively. However, for RA 5, RA 7 and RA 9, the flexural strength was decreased compared to the control for both age, 7 days and 28 days. In conclusion, 3% is the optimum content of rubber ash in concrete prism for both concrete age