Influence of Different Types of Fillers and Additives on the Performance of Warm Mix Asphalt

Abstract

Warm Mix Asphalt (WMA) and technologies become vivid in use in the most of countries around the world, therefore this technique must be applied in Iraq. WMA processes were developed to reduce the mixing and compaction temperatures of hot mix asphalt (HMA) without losing the quality of the resulting pavement. To achieve this goal, the study is required to use two kinds of binder from different refineries in the current study. The method is followed in mixing that with local aggregate and two kinds of fillers (lime stone &cement) that mix with two kinds of foaming additives (natural Zeolite & synthetic Zeolite) by (0.3%) percent from the weight of mix at different temperatures (120, 130 & 140) °C. For avoiding moisture damage, which is caused by using Zeolite, that contains about 20% of water, hydrated lime in (1%) was used as the perfect treatment for reducing this problem. In this study, asphalt mixtures were designed by Marshall method to determine the optimum asphalt content for each asphalt mix, and then a comparison between HMA and WMA was made by a list of laboratory tests represent by: Marshall properties, volumetric characteristics, Indirect Tensile Strength and creep test to evaluate the permanent deformation. The findings of the study showed that the mixtures (HMA and WMA) with the Portland cement filler type of asphalt Baiji exhibited better performance than those with limestone dust filler type by reducing mixing and compaction temperatures were achieved, allowing the aggregate to be fully coated at lower temperatures than in HMA production.However, asphalt Al-Durah with limestone showed better performance than those with cement. The results also showed that the use of synthetic Zeolite could improve volumetric characteristics, which reduced the air voids. On the other hand, Marshall stability has been improved significantly for WMA with asphalt Baiji than WMA mixture with asphalt Al-Durah when they are mixed WMA with limestone and cement filler, respectively. The maximum Marshall Stability obtained is 11.11 kN and 10.34 kN for mixtures with limestone and cement as a filler, respectively. Overall, natural Zeolites with limestone enhanced both the moisture sensitivity and the resistance to permanent deformation of WMA. Hydrated lime as anti-stripping additives had a significant effect on the performance characteristics of asphalt mixes. Lower production temperature and different additives with different filler effects on the performance tests’ results. Zeolite with hydrated lime replacement addition with filler to asphalt mixtures improved the resistance of moisture damage and permanent deformation concerning reference mix despite the decrease of the mixing and compaction temperature.