Indication is given of the thickness of the surface layer and of the mean texture depth (MTD) measured with a volumetric patch technique. The road surfaces are defined by the generic name of the technique, and the grading size. The pass-by noise level of a passenger car being driven on seven types of road surfaces (DAC, VTAC, PAC, SD8/10, SSD0.8/1.5, PCC, and CC) at 90 km/h was investigated for different temperature conditions where classic tire (Tire A) and winter tire (Tire B) were tested.
The larger ring size used in the ASTM C1701 method or the double-ring method could reduce the variability of the permeability measurement. The permeability measured by the ASTM C1701 method was more conservative (i.e., lower than that with the NCAT permeameter) and on average about 25% of the values measured by the NCAT permeameter method. The correlation was stronger ( R 2 = 0.72 through 0.9) when the measured permeability values were for a single type of pavement surface material. 3.Ī weak correlation (with R 2 = 0.52) was observed between permeability measurements made by the NCAT permeameter and the ASTM C1701 method across all pavement surface types. 2.īoth the ASTM C1701 and the NCAT permeameter measurement methods can effectively be used to measure the permeability of all surface pavement types and their mix design will not significantly influence the measurement accuracy. It was found that silicone gel is superior for water sealing compared with the plumber's putty recommended by both methods. The conclusions drawn from the study include: 1.įor accurate permeability measurement, regardless of the method of measurement, water leakage must be prevented. The permeability of test sections was comparatively measured for porous asphalt, pervious concrete, and permeable interlocking concrete paver pavements using both the American Society for Testing and Materials (ASTM) C1701 and the National Center for Asphalt Technology (NCAT) methods (using constant-head and falling-head methods, respectively see Chapter 5). Because of the open structure of the pavement, porous asphalt offers a means to replenish water tables and aquifers rather than forcing rainfall into storm sewers, porous asphalt also helps to reduce demands on storm sewer systems. Moreover, the porous asphalt pavement does not require proprietary ingredients and does not require special paving equipment. While slightly coarser than standard asphalt, porous asphalt pavements are acceptable. in depth, provides a sub-base for the asphalt paving. However, the stone bed size and depth must be designed so that the water level never rises into the asphalt. As the water drains through the porous asphalt and into the stone bed, it slowly infiltrates into the soil. Porous asphalt pavements are constructed in the form of an underlying, open-graded stone bed that provides drainage for the water. And, like other asphalt pavements, they can be designed for many situations. The performance of porous asphalt pavements is similar to that of other asphalt pavements. With proper design and installation, porous asphalt can provide pavements with a lifespan of more than 20 years and provide storm-water management systems that promote infiltration, improve water quality, and often eliminate the need for a detention basin. Such pavements have been proving their worth since the mid-1970s, and recent changes in storm-water regulations have prompted many consulting engineers and public works officials to seek information about them. Porous asphalt pavements, used mostly for parking lots, allow water to drain through the pavement surface into a stone recharge bed and infiltrate into the soils below the pavement. Porous asphalt pavements offer developers a new option for managing storm water.
Speight PhD, DSC, in Asphalt Materials Science and Technology, 2016 8.2.6 Porous Asphalt