Laboratory evaluation of high-friction thin overlays for pavement preservation

Traditional asphalt concrete(AC)and stone matrix asphalt(SMA),which are used as thin asphalt overlays,are common maintenance strategies to enhancing ride quality,skid resistance,and durability.Recently,several studies have used a novel asphalt mixture known as a high-friction thin overlay(HFTO)to improve surface characteristics.However,it remains uncertain whether the laboratory properties of HFTO differ significantly from those of conventional mixtures.This study aims to evaluate the laboratory properties of HFTO mixtures and compare them with those of AC and SMA.Those mixtures with nominal maximum size of 9.5 mm were produced in the laboratory,and performance tests were conducted,including wheel tracking test,low temperature flexural creep test,moisture susceptibility test,Cantabro Abrasion Test,Marshall Test,sand patch test,British pendulum test,and indoor tire-rollingdown test.The results showed that the HFTO exhibited a lower tire/pavement noise than the AC and SMA.Additionally,HFTO had superior high-temperature stability,larger macro texture,and higher skid resistance in comparison to those of AC,but lower than those of SMA.Consequently,HFTO mixtures may be considered a suitable replacement for traditional AC mixtures in regions where skid resistance and noise reduction are concerns.

Noise emission of concrete pavement surfaces produced by diamond grinding

In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been sys- tematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise- reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.

The acoustical character of low noise asphalt pavements

The acoustical character of low noise asphalt pavement was studied theoretically and experimentally. Its normal incident absorption coefficient can reach 0.5 - 0.7, much better than that of general asphalt pavement, although both are the same in thickness and maximum aggregate size. The connected porosity is the most major parameter, which can control the coefficient. The more the porosity is, the higher the coefficient is. The peak value of normal incident absorption coefficient will increase and move towards lower frequency when the depth of pavement is thickened. The peak will approach a stable value when the depth is about 40 mm. The measurement results show that the traffic noise can reduce 4 dB - 8 dB at a test low noise asphalt pavement when a car speed is more than 60 km·h-1

Developing a Durable Quiet Road Surface

Road traffic noise can have a significant impact on the quality of life for residents close to major road networks.One of the most effective measures for reducing the noise from road traffic,particularly on high-speed roads,is to ensure the use of a low noise road surface.Research on pavement construction and the measurement of its acoustic properties has shown that significant noise reductions can be achieved through the use of certain road surface types.However certain low noise road surfaces do not exhibit the desired durability associated with more traditional pavements,leading to costly and disruptive maintenance regimes.This article looks at the mechanisms involved in tyre/road noise generation and how these interact with various road surface properties including a brief overview of some common surface types.It then goes on to explain how these concepts informed the development of an asphalt surfacing material with enhanced durability and good acoustic performance without compromising safety.Progress in testing the resulting Premium Asphalt Surfacing System(PASS)is outlined,including the completion of a successful network trial.