CONCRETE PAVEMENT PROGRESS 14 WWW.ACPA.ORG created by diamond grinding also enhances macro texture and skid resistance in polished pavements. DIAMOND GRINDING USES FEWER RESOURCES Research shows a correlation between rough pavements and reduced driving speeds, which can lead to congestion. Pavement congestion can increase drive times and idle time on highways, resulting in higher fuel consumption. Smooth pavements can help increase driving speed thus reducing roadway congestion. The nature of diamond grinding makes it one of the most efficient pavement preservation techniques. It can be completed in short lane closures for less time than typical asphalt overlays and may even be performed in a rolling closure next to live traffic. Overlays require the mining, producing and hauling of virgin material. Each one of these steps has a significant cost and carbon impact to the project. Comparatively, a diamond grinding project only requires the removal of a small amount of material from the jobsite in the form of slurry. It is also important to consider the life-cycle cost of paving and rehabilitating both types of pavement surfaces. An asphalt surface should be replaced approximately 8 to 15 years into its life with a new layer of asphalt. In that time frame and given the material hauling parameters, it is unlikely that asphalt overlays have the opportunity to be cost or carbon neutral. Diamond grinding on concrete pavements can last decades before requiring remediation. Pair this with the aforementioned material mining and hauling benefit, as well as the re-opening of concrete surfaces for carbon sequestration, and cost carbon neutrality becomes commonplace for diamond grinding. Highways with heavy traffic can even show a net negative cost and carbon impact. Safer Surfaces Highway users are constantly at risk of motor vehicle accidents. Rough pavements increase this risk because they can cause the suspension of the vehicle to bounce. In extreme instances, this can result in tires leaving the surface of the pavement, causing them to momentarily lose friction. Potholes also can jolt the steering mechanism of a vehicle, causing the operator to lose control. Proactive drivers may even swerve to continued from page 13 avoid potholes, causing them to depart from their driving lane and increasing the risk of contact with vehicles in adjacent lanes. Surface irregularities may impact drainage during wet weather events, increasing the risk of hydroplaning. Additionally, aggregates (rocks) dislodge and ravel out of an asphalt rubber overlay as it ages. These loose rocks lay on the pavement, acting like marbles on the roadway surface and reducing the braking ability of tires. This raveling of the pavement is also the reason the asphalt rubber gets louder over time. The University of Maryland compiled data from the United States, Australia and New Zealand. The results suggested a linear correlation between pavement roughness and vehicle accidents. The document also noted that pavements with ten millimeters (mm) of rutting showed a higher risk and higher severity of vehicle accidents. Concrete pavement preservation (CPP) with diamond grinding is proven to be safer, with 42% fewer accidents in all-weather conditions when compared to a tined pavement surface. And construction required to perform diamond grinding is a safer alternative as well. Diamond grinding can be constructed all year long in day and night shifts without closing the freeway. This allows for construction at times that least impact the consumer, unlike asphalt rubber, which can only be placed during certain times of the year. Diamond grinding significantly reduces the amount of traffic congestion and consumer delays during construction as well, which results in far fewer accidents. DIAMOND GRINDING
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