Wardati Hashim

Cooling time of porous asphalt pavement affecting compaction process due to various raining condition

While bright sunshine and warm temperatures make for the best paving weather, construction projects can get a bit rough in adverse weather conditions. In this case, porous asphalt is used on paving. Light sprinkles can usually be handled without any serious problems. Moderate rainfall events, on the other hand, will generally require the paving project to be postponed. Steady downpours will cool the porous asphalt mix and make proper compaction extremely difficult to obtain. For the viability of the project, contractors will always wait until the sky clears up. According to the JKR Specification 4(Clause 4.2.6.4), it clearly states that no pavement work should be done during rain. The rain is a cold medium where it will actually cools down everything that make contact with the water. Whereas, the mix porous asphalt (PA) is a hot medium. When these two elements combined, the surface and the PA will harden at a stage where it will not be well compacted. This will cause problems in the future. The test is conducted by pouring water onto the pavement(through raining simulation).Since the rain intensity can be determined by the size of the rain drops, the difference in the shower hole size is good enough to create different rain intensities to predict the PA cooling rate when it makes contact with water. These two variables will work as a comparison in this study between raining and no rain condition. As a result, whenever the water make a contact with the PA, the rates of cooling drops 98% from the normal rates of cooling of PA (without rain)giving the Time Available for Compaction (TAC) to be less than 60 seconds. This study may be a knowledge on how the rates of cooling work if the PA make contact with water. It can also be used as future reference on the study of cooling rates of porous pavement during raining condition.

Rutting performance of cold bituminous emulsion mixtures

Cold Bituminous Emulsion Mixture (CBEM) is an environmentally friendly alternative to hot mix asphalt (HMA) for road surfacing, due to its low energy requirements. However, CBEM has generally been perceived to be less superior in performance, compared to HMA. This paper details a laboratory study on the rutting performance of CBEM. The main objective of this study is to determine the Marshall properties of CBEM and to evaluate the rutting performance. The effect of cement in CBEM was also evaluated in this study. The specimens were prepared using Marshall Mix Design Method and rutting performance was evaluated using the Asphalt Pavement Analyzer (APA). Marshall Properties were analysed to confirm compliance with the PWD Malaysia’s specification requirements. The rutting performance for specimens with cement was also found to perform better than specimens without cement. It can be concluded that Cold Bituminous Emulsion Mixtures (CBEM) with cement is a viable alternative to Hot Mix Asphalt (HMA) as their Marshall Properties and performance obtained from this study meets the requirements of the specifications. It is recommended that further study be conducted on CBEM for other performance criteria such as moisture susceptibility and fatigue.Cold Bituminous Emulsion Mixture (CBEM) is an environmentally friendly alternative to hot mix asphalt (HMA) for road surfacing, due to its low energy requirements. However, CBEM has generally been perceived to be less superior in performance, compared to HMA. This paper details a laboratory study on the rutting performance of CBEM. The main objective of this study is to determine the Marshall properties of CBEM and to evaluate the rutting performance. The effect of cement in CBEM was also evaluated in this study. The specimens were prepared using Marshall Mix Design Method and rutting performance was evaluated using the Asphalt Pavement Analyzer (APA). Marshall Properties were analysed to confirm compliance with the PWD Malaysia’s specification requirements. The rutting performance for specimens with cement was also found to perform better than specimens without cement. It can be concluded that Cold Bituminous Emulsion Mixtures (CBEM) with cement is a viable alternative to Hot Mix Asphalt (HMA) as their M...

Rutting resistance of asphalt mixture with cup lumps modified binder

Rutting is the most common pavement distress in pavement structures which occurs mainly due to several factors such as increasing of traffic volume, climatic conditions and also due to construction design errors. This failure reduced the service life of the pavement, reduced driver safety and increase cost of maintenance. Polymer Modified Binder has been observed for a long time in improving asphalt pavement performance. Research shows that the use of polymer in bituminous mix not only improve the resistance to rutting but also increase the life span of the pavement. This research evaluates the physical properties and rutting performance of dense graded Superpave-designed HMA mix. Two different types of dense graded Superpave HMA mix were developed consists of unmodified binder mix (UMB) and cup lumps rubber (liquid form) modified binder mix (CLMB). Natural rubber polymer modified binder was prepared from addition of 8 percent of cup lumps into binder. Results showed that all the mixes passed the Superpave volumetric properties criteria which indicate that these mixtures were good with respect to durability and flexibility. Furthermore, rutting results from APA rutting test was determined to evaluate the performance of these mixtures. The rutting result of CLMB demonstrates better resistance to rutting than those prepared using UMB mix. Addition of cup lumps rubber in asphalt mixture was found to be significant, where the cup lumps rubber has certainly improves the binder properties and enhanced its rutting resistance due to greater elasticity offered by the cup lumps rubber particles. It shows that the use of cup lumps rubber can significantly reduce the rut depth of asphalt mixture by 41% compared to the minimum rut depth obtained for the UMB mix. Therefore, it can be concluded that the cup lumps rubber is suitable to be used as a modifier to modified binder in order to enhance the properties of the binder and thus improves the performance of asphalt mixes.

Marshall properties and rutting resistance of hot mix asphalt with variable reclaimed asphalt pavement (RAP) content

Hot mix recycling is the process in which reclaimed asphalt pavement (RAP) materials are combined with new materials to produce hot mix asphalt mixtures. This paper details a laboratory study in which the effects of different RAP contents were evaluated on the performance of hot recycled mixes. The objective of this study is to evaluate the rutting resistance of asphalt mixes containing different percentages of RAP. The Marshall mix design method was adopted in this study to determine the OBC for the asphalt mixes containing four aggregate combinations with RAP contents of 0% (control), 15%, 25% and 35%. Volumetric analysis was performed to ensure that the result is compliance with specification requirements. The resilient modulus test was performed to measure the stiffness of the mixes while the Hamburg wheel tracking test was used to evaluate the rutting performance of these mixes. The results obtained showed that there were no substantial differences in volumetric properties, stability values and stiffness properties between the control mix and recycle mixes. It can be concluded that recycled mixes performed as good as the performance of conventional Hot Mix Asphalt (HMA) in terms of resilient modulus and rutting.

Time Gap Evaluation due to the Existence of Heavy Vehicles on Urban Expressways

Time gap is important for road user to make decision relative to the lad vehicle at a roadway segment. Theoretically, if the gap is larger than reaction time, drivers would maintain the safe following distance from the vehicle in front or else the probability of vehicle collusion is considerably high. In expressways, gap is important for the purpose of lane changing and overtaking. Due to high allowable speed on expressways, time gap might be affected, especially with the consideration of heavy vehicle existence. This paper attempts to statistically justify any significance correlation between speed and time gap in relative to critical gap acceptance pertaining to the heavy vehicles and cars interaction on urban expressways. Extensive data was collected through video recording before being abstracted and processed by utilizing the TRAIS software. Then, statistical analysis in relative to the speed and time gap for various vehicles interactions are presented. The results showed there is a significant correlation between speed and time gap for all vehicles interaction. When cars following other cars at allowable average speed, the time gap is relatively low leading to a lower critical gap acceptance as compared to the situation with the existence of heavy vehicles.

Physical and Rheological Properties of Aged Bitumen Rejuvenated with Waste Engine Oil

Age hardening of bitumen is one of the factors affecting the durability of asphaltic concrete pavements. As the bitumen ages, its viscosity increases and it becomes more stiff and brittle. Recycling agents have been used to restore or soften the aged bitumen properties to a consistency level appropriate for use in the recycling process of deteriorated pavements. This paper details a study on the use of Waste Engine Oil (WEO) from vehicles as a recycling agent for aged bitumen. The study focused on the rheological properties evaluation of virgin bitumen, aged bitumen and blended bitumen (50% of fresh bitumen + 50% of aged bitumen) mixed with waste engine oil as additive (with 0%, 3%, 6% and 9%). The aged bitumen was prepared through the process of Rolled Thin Oven Test (RTFOT) and Pressure Aging Vessel (PAV) test to simulate the aging process. The virgin bitumen, the aged bitumen, and the blended bitumen mixed with various proportions of WEO were then tested to determine their physical characteristics. Penetration, softening point, viscosity and dynamic shear rheometer (DSR) tests were conducted in order to determine rheological properties of the bitumen samples prepared. The penetration value of blended bitumen added with WEO increased with the addition of WEO. The softening point decrease with the percentage increased in WEO of the blended bitumen. The viscosity for the blended bitumen added with WEO decreases with the increase in the percentage of WEO added. The DSR results showed that the increase in the amount of WEO in blended bitumen decrease the G*/sin δ parameter. For the particular bitumen and WEO used, the optimum percentage of WEO is 6% by the total weight of bitumen as it complies with the Public Works Department of Malaysia’s specification requirements. This study suggests that WEO has ability to counteract the stiffening of aged bitumen and restore the aged bitumen to that of virgin bitumen. As the composition and performance of bitumen and WEO may be different from those used in this study, it is recommended that a detailed evaluation is carried out for the bitumen and WEO to be used in asphalt recycling.