AASHTO PP 44-01 pdf free download

AASHTO PP 44-01 pdf free download.Quantifying Cracks in Asphalt Pavement Surface.
2. CRACKING DEFINITION AND ESTIMATION 2.1. General Guidelines- Each agency shall designate the lane(s) and direction(s) of travel to be surveyed or rated based on sound engineering principles and management needs within the agency. The following guidelines are recommended as minimums to provide long-term uniformity: 2.1.1. Survey a 2.500-m (8-ft) strip in the outside lane as shown in Figure 1. As another option, survey the 3.6-m (12-ft) full lane width. 2.1.2. For undivided highways, survey one direction. 2.1.3. For divided highways, survey the outside lane in both directions.2.1.4. For each survey cycle, it is desirable to use the same direction(s) of travel and survey lane(s). 2.2. Cracking Definition and Types– A crack is a discontinuity in the pavement surface with minimum dimensions of 1-mm (‘/2s-in.) width and 25-mm (1-in.) length. Cracks may include longitudinal cracks, transverse cracks, and interconnected cracks. The intent of this practice is to quantify and differentiate between load-associated (fatigue) and nonload-associated (environmental, reflective, etc.) pavement cracking and joints. 2.2.1. For this practice, increased cracking intensity in the wheelpath as compared to the nonwheelpath areas is assumed to quantify load-associated cracking. 2.2.2. Nonload- associated cracking is quantified by the cracking measured in the nonwheelpath areas. 2.2.3. Sealed cracks will not be quantified by manual surveys. Automated survey equipment will not quantify any discontinuity greater than 25-mm (1-in.) width. 2.3. Cracking Estimates by Type: 2.3.1. Rating Wheelpath Cracks- _Wheelpath cracking is determined in both the inside and outside wheelpath as shown in Figure 1. . 2.3.2. Rating between Wheelpath Cracks- -Nonwheelpath cracking is determined in the area between the wheelpaths as shown in Figure 1.2.3.3. Determining any additional nonwheelpath cracking for the remainder of the lane width is optional and will be defined by the agency. 2.3.4. Classify cracking by severity and intensity as indicated below.2.3.4.1. Severity Level 1- Cracks < 3 mm (< ‘/g in.). 2.3.4.2. Severity Level 2- Cracks with dimensions > 3 mm (> ‘/g in.) and < 6 mm (< /4 in.) width. 2.3.4.3. Severity Level 3- Cracks with dimensions > 6 mm (> ‘/4 in.) width. 2.3.5. Quantify intensity of cracking at each level as the total length of cracking per unit area (m/m2) for each defined survey strip as shown in Figure 1. Note 2- -The sample area is a function of the sample length the agency has chosen in Section 3. 3. RECORDING OF DATA 3.1. Automated Surveys- -The entire length of the pavement shall be surveyed (100 percent sample). The data summary interval shall be 0.1 km (0.062 mi). 3.2. Manual Surveys- The number of samples for a given homogeneous section of pavement is determined by the desired confidence level and the variance in the samples. The minimum 85 percent confidence interval of the mean should be no greater than 10 percent of its value. Each section shall have at least four samples. For the purpose of establishing the confidence level, the total crack length for all severity levels within a survey strip may be added together. Table 1 shows the confidence interval for example sample counts and confidence levels as a function of the standard deviation of the samples. It is understood that the samples should be distributed throughout the section.AASHTO PP 44-01 pdf download.