Experiences with half-warm foamed bitumen treatmant process in the Netherlands
<p>For decades foamed bitumen was used worldwide for the production of cold mixes, but one of the disadvantages of this process was that the fines were coated completely with bitumen and the coarse aggregate particles were only partly coated with bitumen. As a consequence of this cold foamed bitumen asphalt mixes are less durable than hot mix asphalt. Recently the half-warm foam (HWF) process was developed, which provides a much better coating of the coarser particles with bitumen, resulting in increased mechanical properties and durability of the mix. Be<span>cause the mixing temperature of the HWF process is about 95</span><span>°</span><span>C also considerable energy savings and decrease of emission (fumes) can be reached. For environmental reasons the policy of the Dutch government is to: <span>• </span>reduce energy consumption during manufacturing of asphalt mixes <span>• </span>decrease emissions during manufacturing and laying of asphalt mixes <span>• </span>reuse Reclaimed Asphalt Pavement (RAP) for the production of hot mix asphalt in as high amounts as possible. Of course these goals should not lead to shorter service life of asphalt mixes. One of the possibilities to reach these goals is to make use of the half-warm foamed bitumen treatment if the durability and performance of the HWF asphalt mixes are equal to those of hot mix asphalt.</span></p>