No abstract

Porous asphalt (PA) is widely used in a growing number of countries where porous asphalt is applied for a variety of purposes, e.g. for the effective drainage of rainwater, traffic safety (high slip resistance), the control of noise pollution and lower temperatures surrounding the city. However, it has many other disadvantages, such as poor resistance to rutting, poor resistance to fatigue, and PA is susceptible to raveling (wastage of aggregates from the pavement surface), due to effects of climatic and traffic loading. In general, this type of mixtures is not as good as traditional mixtures. This research aims to study and improve the properties of porous mixtures using SBS. In this paper, laboratory tests were carried out to the materials involved in the composition of this mixture: binder, aggregate, and additive. SBS is used in the proportion of (2.0, 3.0, and 4.0) % of the weight of the binder. It was found that this additive leads to reduce the permeability and air void, but not as large as that without polymer modifier by (1.7 %, 3%, and 3.5%), while in the case of abrasion loss (aged and unaged) decrease by (4.1, 6.67 and 10.92) (4.7, 6.3and 2.6)% respectively. The drain down value is decreased by (16.5%, 38.25%, and 43.51%) respectively, from original asphalt cement.

The increase in heavy traffic load due to increasing number of vehicles and trucks with the effects of other exterior factors such air temperatures and moisture have caused distresses on pavement. In this study, the influence of laboratory aging on the mechanical properties of Polyethylene-modified concrete mixtures was studied utilizing different experiments. Polyethylene Terephthalate (PET) waste plastic bottles was used at different percentage i.e. 1%, 2%, 3%, and 5% by weight of bitumen. The design bitumen content was obtained for dense mixture according to superpave system. Marshall Stability, Flow, indirect tensile strength, and tensile strength ratio at two aging levels are conducted to evaluate the performance change of asphalt mixtures. Mixtures were conditioned at shortterm aging temperature of 135°C for different time periods (2, 6 and 8 hrs). Long-term aging was completed after compaction of test specimens to the desired air void level of 4 ± 0.5% using Superpave gyratory compactor at three different temperatures (75, 85 and 95) °C and four aging periods (0, 2, 5, and 10 days. The results showed that adding PET polymer to paving blend has good significance; it improved stability, flow, HMA density in addition to moisture resistance because of great elastic ability provided by PET particles, it can be found that 4 and 5% of PET content gave the best results as compared with the control mixture.

No abstract

Moisture damage is one of the most common reasons for the premature deterioration of Hot Mix Asphalt (HMA) pavements. Over the years, extensive research has been carried out by scientists and engineers on this subject; however, pavements still succumb to early failure from infiltrating moisture. A very popular method of minimizing the moisture susceptibility of asphalt pavements is by the use of anti-stripping agents. These additives are chemical substances that alter the physicochemical properties of the asphalt by making it more hydrophobic. This study focuses on the effect of antistripping agents on the moisture susceptibility of asphalt Concrete mixture. The anti-stripping agents used were (SBS, Silica fume, and SBS with Silica fume) with different percentages. The laboratory tests include indirect tensile strength test, Marshall and retained Marshall Stability test (RMS) and double punching shear strength test. The test results show that the asphalt mixtures modified by (Silica fume+ SBS) have highest values in Marshall Stability, RMS and it increased the moisture and stripping resistance. However, using (3% Silica fume+3% SBS) has the best effect on Marshall Stability, TSR value and stripping resistance. While (4% Silica fume+3% SBS) has the best effect on RMS value. From the experimental results, it is observed that the addition of anti-stripping agents had a significant positive influence on the results of the test properties being evaluated in each test.