Ahmad Kamil Arshad

Assessing Pedestrians’ Perspective on the Walkability of Pedestrian Environment Under Mixed-Use Development

Walkability is define as to which extent does the built environment support and encourage walking. Many challenges faced by local authorities in providing a highly walkable built environment to the pedestrian causing the facilities being abandoned by the users. In order to encourage walkability, the qualities of built environment must meet the pedestrians’ expectation. On-street questionnaire survey was conducted on two different sidewalk segments within mixed-use development in Kuala Lumpur City Centre in order to assess the pedestrians’ perception and expectation on sidewalk facilities. The respondents were asked to give rating on different sidewalk attributes and the results were analyzed using simplified weighted factor analysis. It was found that only the sidewalk width was given positive result for both sidewalks whereas different results were given for other sidewalk attributes. Besides that, even though safety while using the sidewalk was the most important factor that influence walking decision, the pedestrian felt that improvement should be made in term of sidewalk facilities rather than safety for both sidewalk. In conclusion, the pedestrians do not satisfied with almost all of the existing sidewalk attributes. Improvement should be made in term of sidewalk facilities in order to increased walkability in Malaysian city.

Assessing Pedestrian Profile According to Age and Gender in Central Business District, Kuala Lumpur, Malaysia

Pedestrian activities usually influenced by the pedestrian perception on the quality of the built environment of a city. Challenges faced by local authorities in providing facilities that are suitable for each group of pedestrians due to lack of information on the pedestrian profiles pattern. Therefore, the objective of this paper is to assess on the pedestrian profile pattern in one of the Central business district within Kuala Lumpur City Center that are among the highest pedestrian volume and adequate pedestrian facilities. On-street questionnaire survey was conducted first in order to ensure that the existing pedestrian facilities of the selected area were between acceptable to good quality range. The parameters includes are overall travel experience, sidewalk condition, aesthetic and amenities, crossings, street furniture, personal safety and adjacent traffic. Then, Pedestrian classification counts were carried out on afternoon peak-hour for one whole week. From the result, similar pedestrian profile pattern were observed on Monday to Thursday and the number of trips made increased on weekends for both count location. The result also shows that female pedestrian, especially in the 18 to 34 age range made the highest number of trips. In overall, the female pedestrian used the existing pedestrian facilities more than male for every group profile except for elderly person with disabilities/with prams.

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...

Dynamic modulus of nanosilica modified porous asphalt

Porous asphalt (PA) is a flexible pavement layer with high interconnected air void contents and constructed using open-graded aggregates. Due to high temperature environment and increased traffic volume in Malaysia, PA may have deficiencies particularly in rutting and stiffness of the mix. A possible way to improve these deficiencies is to improve the asphalt binder used. Binder is normally modified using polymer materials to improve its properties. However, nanotechnology presently is being gradually used for asphalt modification. Nanosilica (NS), a byproduct of rice husk and palm oil fuel ash is used as additive in this study. The aim of this study is to enhance the rutting resistance and stiffness performance of PA using NS. This study focused on the performance of PA in terms of dynamic modulus with the addition of NS modified binder to produce better and more durable PA. From the result of Dynamic SPT Test, it shows that the addition of NS was capable in enhancing the stiffness and rutting resistance of PA. The addition of NS also increase the dynamic modulus value of PA by 50%.

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.

Influence of Warm Porous Asphalt on Permeability Reduction Due to Binder Flow

Warm mix asphalt (WMA) is a new technology in Malaysian context. The technology can help to reduce the global warming issues. In this research, the warm mix asphalt technology was used in porous asphalt pavement which is known as warm porous asphalt (WPA) mix. WPA loses permeability mainly due to clogging. Apart from typical clogging agents such as dust and tyre rubber, the binder flow is also another source of permeability reduction. The objective of this study was to investigate the binder flow phenomenon that affected the permeability reduction in WPA. To obtain the binder flow phenomenon, samples were conditioned at 35 °C for 120 days. The different mixing and compaction temperatures with bitumen 60/70 + 3 % RH-WMA additive were used in preparing the samples. A falling head water permeameter was used to determine the permeability loss which is related to time and temperatures. The result from the permeability loss was significant to high mixing temperatures over time. Due to time, self-weight of the binder and high mixing temperature, the asphalt mastic start to flow down according to gravitational forces and finally the coefficient of permeability reduced, yet the time of flow increased. The outcome of this research indicated that the different temperatures during mixing and compaction were significant to the binder flow. Hence, the low mixing temperature using WMA technologies could reduce the clogging problem due to self-weight of the binder.

Moisture-Induced Damage Evaluation of Nanopolymer-Modified Binder in Stone Mastic Asphalt (SMA) Mixtures

This paper presents laboratory investigation on mix design and moisture-induced damage performance of nanopolymer-modified asphalt binder SMA mixture. The effect of nanopolyacrylate (NP) in the mixture was investigated using Marshall mix design and modified Lottman test. Nanopolyacrylate polymer-modified binder was prepared with addition of 0–6 % NP polymer by weight into asphalt binder. Results of SMA14 mixture showed that all the volumetric properties of the mixtures passed the Marshall requirement, which indicates that these mixtures were good with respect to durability and flexibility. The ITS of NC2% and NC4% mixtures increased with an increase in percentage of NP but not as good as the conventional mixture, NC0% which is added with PG76 polymer-modified binder. However, NC6% mixture showed higher tensile strength compared to PG76 modified binder. Results of the moisture-induced damage showed that all the mixes passed the AASHTOT283 criteria with TSR values greater than 80 %. The results also showed that the optimum NP obtained is 6 % by weight of asphalt binder is the most effective and potential proportion to improve moisture-induced damage performance. Thus, addition of nanopolyacrylate polymer to the binder has significantly improved the cohesion as well as adhesion properties of the binder, and hence the performance of stripping.

Abrasion Loss and Binder Draindown of Porous Asphalt with Nanosilica-Modified Binder

This paper details the performance evaluation of porous asphalt (PA) with nanosilica (NS)-modified binder in terms of binder draindown and abrasion loss. Both tests are widely used to evaluate the lower limit and upper limit of the design binder content for porous asphalt. The existence of nanoparticle with different proportions can affect binder draindown and abrasion resistance behavior of PA. Six different percentages of nanosilica were mixed with PEN 60–70 type of binder in this study. Then, all these blended modified binders were used to prepare PA samples using Marshall mix design method. Nanoparticle used in this study was nanosilica with the average size of 10–15 nm. Binder Draindown test was performed using a metal basket with 3 mm perforation. Then, abrasion loss value was evaluated using Los Angeles Abrasion Machine without steel ball. In accordance to PWD of Malaysia Specification for Road Works, which states that binder draindown for PA should not be more than 0.3 % of total weight of sample, while abrasion loss should not be more than 15 % also by weight of total sample. Based on Cantabro loss Test and Binder draindown test, 2–5 % NS are considered as the effective amounts of NS to be mixed with binder in order to reduce the abrasion loss and binder draindown of PA. In addition, 4 % NS is also considered as the optimum NS proportion. The existence of NS is capable to enhance the physical and rheological properties of asphalt binder, while at the same time it disperses well in asphalt binder. Thus, the performance of PA is also enhanced with the addition of NS in the binder.