Author: Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 79
Book Description
Portland Cement Pervious Concrete (PCPC) has an excellent performance history in the Southeastern U.S., but until recently has seen little use in environments with significant freeze-thaw cycles. Therefore, assessment of actual field performance is important. This project documents field observations, and nondestructive testing results of PCPC sites located in the states of Ohio, Kentucky, Indiana, Colorado, and Pennsylvania. PCPC is most often used as a pavement for parking lots. Field performance depends on the quality of the mixture as well as proper control of construction and curing. In addition to field observations and nondestructive testing, laboratory testing was performed on cores removed from some of the test sites. Generally, the PCPC installations evaluated have performed well in freeze-thaw environments, with little maintenance required. Construction, use, and maintenance information was obtained during the site visits. The field investigation plan encompassed a thorough visual inspection for signs of distress, two types of surface infiltration measurements, and ultrasonic pulse velocity (UPV) testing at the Ohio, Kentucky, and Indiana sites. At the Colorado and Pennsylvania sites, only one type of surface infiltration test was made. Visual inspection documented cracking and surface raveling, as well as areas that appeared to be clogged. One type of field infiltration test, developed during this research project, used the time to drain a 4 by 8 inch plastic cylinder through a 3/4 inch hole down into the pavement. The second test was used to identify whether pavements required maintenance. The UPV was used in indirect transmission mode, because only the surface of the pavement was accessible. At six of the sites, it was possible to extract cores for laboratory testing. The cores were brought back to the laboratory and tested for void ratio, hydraulic conductivity, and direct transmission UPV. Direct transmission is considered to be more reliable than indirect transmission for UPV. Once these tests were completed, some of the specimens were tested for compressive or splitting tensile strength. Some of the cores were cut into top and bottom specimens, to compare the properties through the pavement thickness. The data are recorded in tables and plots. Significant differences were observed between cores from pavements that used gravel and crushed limestone coarse aggregates. The use of gravel as a coarse aggregate may facilitate more effective and uniform compaction. The laboratory hydraulic conductivity results were plotted against the field drainage times, so that in the future the field test may be used to estimate PCPC infiltration capability. The installations have not shown any signs of freeze-thaw damage. Some pavements have had surface raveling, which generally stops after a few months of use. Saw cut joints had less raveling than tooled joints. A few have cracks, which may be attributed to overloading or long spaces between joints. Some of the pavements had very poor infiltration capability due to improper installation. Most of the installations are performing well, but it is also true that many in the area are relatively new. Therefore, they should be examined again in the future, probably at 5 and 10 years from the publication of this report. This report serves as a benchmark of the pavement condition observed at the time of this study.
