Showing papers by "Ali Maher published in 2004"

Geotechnical properties of stabilized dredged material from new york-new jersey harbor

Abstract: As a result of the ban on the disposal of contaminated dredged sediments in the New York Bight, the states of New York and New Jersey have embarked on a rigorous program of seeking environmentally friendly solutions to handling dredged material, including beneficial use of stabilized dredged material (SDM) in roadway applications. A pilot study was initiated in 1998 to construct two embankments on a site in Elizabeth, New Jersey, where SDM was successfully used as a cover for more than 100 acres of commercial development area. The pilot study included a laboratory phase for geotechnical evaluation of SDM and a field phase for monitoring and evaluating the construction process as well as the performance of the fills after construction. The results of the laboratory phase indicate that SDM satisfies most geotechnical criteria for fill construction—except those for durability—requiring proper coverage and protection similar to those provided for fills constructed on cohesive soils.

Evaluation of crumb rubber in hot mix asphalt

Abstract: An asphalt-rubber hot mix asphalt (AR-HMA) design was created using a Superpave 12.5-mm gradation and #30(-)mesh crumb rubber at 20% total weight of the asphalt binder. At this point in time, asphalt rubber has only been used with HMA that contains a more open graded nature, such as open graded friction course (OGFC). However, OGFC is limited in its use due to its potential problems (i.e., clogging and winter maintenance). However, a 12.5-mm Superpave mix may be used on almost any roadway in New Jersey and is most commonly found as the surface course. It is used for both new construction and rehabilitation projects. Therefore, this mix type has the largest potential for usage, meaning that more tires can eventually be recycled. However, two factors need to be considered prior to acceptance: performance and cost. Four HMA mixes were constructed and tested in this study: three baseline mixes using a PG64-22, PG70-22, and a PG75-22 asphalt binder, and the AR-HMA mix which used crumb rubber blended with the same PG64-22 asphalt binder. The influence of crumb rubber particle size on the compaction properties during the mixture design procedure was also evaluated. This would provide a method of comparing the final mixture performance of different performance graded binders to the AR-HMA mix. This type of methodology of testing the mixtures is extremely important due to the necessity of ensuring the crumb rubber complying to the aggregate gradation volume limitations and how the crumb rubber interacts with this volume limitation under performance testing. Therefore, a number of different performance tests were conducted on the four different HMA mixes: 1) Asphalt Pavement Analyzer; 2) Repeated Load Permanent Deformation testing using the Simple Performance test specification; 3) Dynamic Modulus; 4) Repeated Shear at Constant Height; 5) Frequency Sweep at Constant Height; and 6) Simple Shear at Constant Height. The results from the mixture design portion concluded that to provide consistent compactibility when using crumb rubber in a 12.5-mm Superpave design, the maximum particle size should not be greater than a #30 mesh. The performance tests concluded that the AR-HMA mix performed as well as or better than the PG76-22 for every test conducted. For example, the dynamic modulus test results showed that the AR-HMA had similar stiffnesses to the PB76-22 at the high test temperatures, however, the AR-HMA had a much less stiffness at the low test temperature. This indicates that the AR-HMA mix design in this study will provide excellent rut resistance, while also providing excellent low temperature cracking resistance. Essentially, by adding the crumb rubber to the PG64-22, the working temperature range of the asphalt binder increased on both the high and low sides. Also, by performing similarly to the PB76-22, Bayshore Recycling now can establish a cost comparison using the difference in cost between a HMA with a PG64-22 and a PG76-22.

Demonstration Project - The Measurement of Pavement Noise on New Jersey Pavements Using the NCAT Noise Trailer

Abstract: A demonstration project was conducted for the New Jersey Department of Transportation (NJDOT) to evaluate the measurement of pavement/tire noise on New Jersey pavements. The pavement/tire noise is defined as the noise directly produced by the tire traveling over the pavement surface. It does not consider other traffic-related noise such as automobile/truck engines, braking, etc. This is important since the only factor the NJDOT can truly control to aid in the traffic noise reduction is the pavement surface. The demonstration project was developed to provide two key pieces of information: 1) An evaluation of the National Center for Asphalt Technology (NCAT) Noise Trailer as a means of measuring pavement/tire related noise, and 2) An initial database of noise values for different pavement surfaces that are typically encountered on New Jersey highways. The NCAT Noise Trailer uses the Close-Proximity Method to measure the pavement/tire noise. In this method, microphones are placed near the pavement/tire interface to directly measure the pavement/tire noise levels. The microphone set-up and tires are enclosed in a chamber that is insulated with noise absorbing insulation. This provides an enclosure that is only measuring the noise developed by the pavement/tire interface and not any external noise of the passing vehicles or environment. The NCAT Noise Trailer was evaluated for repeatability and also to evaluate the effect of traffic speed on the pavement/tire noise. Results of the testing showed the repeatability to be quite consistent, with an average standard deviation of 0.15 decibels, as long as the test section is greater than 0.1 mile. The standard deviation proved to increase when the test section was less than 0.1 mile, such as for bridge decks. The effect of traffic speed was evaluated by testing the same pavement section at three different speeds: 55, 60, and 65 mph. The results indicated that the 55 mph speed produced the lowest pavement/tire noise and that it can be assumed that the noise increases linearly (at least within this range of traffic speed). The NCAT Noise Trailer was also used to develop an initial database of pavement/tire noise levels for different pavement surfaces tested. In general, the portland cement concrete sections produced the loudest pavement surface while the open-graded friction course produced the lowest pavement/tire noise.