AbstractsEngineering

Porous Asphalt Clogging Performance Under Swedish Conditions; Igensättning av bullerreducerade beläggningar under svenska förhållanden

by Fuad Ahmed




Institution: KTH Royal Institute of Technology
Department:
Year: 2015
Keywords: Air voids; clogging; noise; porous asphalt; X-ray; maintenance; Hålrum; igensättning; buller; bullerreducerande beläggning; tomografi; rengöring; Engineering and Technology; Teknik och teknologier; Civilingenjörsexamen - Samhällsbyggnad; Master of Science in Engineering - Urban Management
Record ID: 1356292
Full text PDF: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166560


Abstract

Porous asphalt has gradually gained a lot of popularity in the past ten years for its ability to reduce traffic noise, especially noise generated between tire and road surface. The acoustical absorption properties are mainly due to the pore structure and the texture of the mixture. However, the percentage of these pores decrease during the lifetime. The main reason is that dirt and organic material get stuck in the air void structure and eventually cause clogging. In Nordic countries, particles from the road which get released due to the use of spiked tires accelerate clogging. To minimize wear and tear of these roads, larger aggregates are used. But, larger stone size diminishes the noise absorption ability of the mixture. Another reason that is attributed to void reduction is post-compaction. The fact that these mixtures damage prematurely and need more maintenance than conventional pavements is the main reason for its limited use. Given these problem, it is therefore important to understand how clogging can be minimized and/or reverted via operational maintenance actions. Different types of cleaning vehicles have been used previously to restore porosity. Unfortunately, these cleaning attempts have led to ambiguities and the effect of cleaning is widely debated. A method to look inside and to measure this effect is needed. This thesis has compared nine field core samples of porous asphalt from E4 Huskvarna, with the aim to conduct an in depth analysis of the air voids distribution before and after cleaning with a particular cleaning method. For this, the Skanska maintenance vehicle was selected, named VägRen  which is claimed to be optimized for porous asphalt under Nordic conditions has been used to clean a 100 m section. Cores were drilled before and after cleaning. The samples were scanned with high resolution X-ray computed tomography (CT) scanner in order to capture the entire morphology.  The digital image analysis program, AvizoFire® was used to characterize the 3D internal structure of air voids. Porosity evaluation as a function of depth of the asphalt layers has been studied to analyze the void distribution and cleaning effectiveness of the dirt with the investigated method. The results show that: (i) No visible damage induced by VägRen could be detected. (ii) Skanska's maintenance vehicles increased the air voids in the entire cleaned core and connected air voids increased by 83 %. The knowledge generated from this study can assist in the broader understanding of effectively utilizing porous asphalt under Nordic Conditions, though more research will be needed for conclusive results on the general effectiveness of the cleaning method and the effect of the life time of the pavement.  ; Intresset för att använda bullerreducerande beläggningar har gradvis ökat de senaste tio åren på grund av dess förmåga att reducera trafikbuller och i synnerhet det buller som genereras mellan däck och vägbana. Den bullerreducerande förmågan beror främst på beläggningens textur…