Rehabilitation of Asphalt Concrete Pavements: Initial Evaluation of the SPS–5 Experiment—Final Report

APPENDIX A

Appendix A includes an overview and summary, as of the time of this report, of each SPS–5 project relative to the experiment plan. Each overview includes a general description of the project’s location and specific values for the key factors of the experiment factorial (table 1). Deviations from the initial project nomination and difficulties reported during construction are identified and briefly discussed. In addition, a summary of the materials data that are available is provided. As stated in chapter 2, the number of tests required for each project varies with the number of supplemental sections built within each project.

A summary of the data completeness for each project is presented in tabular format for construction and monitoring data elements. Data completeness and any project deviations are used in determining an adequacy code that is assigned to each project. This code represents a numerical scale from 0 to 5 and provides an overall rating of the project in regard to fulfillment of the original experimental objectives and expectations. This numerical scale is:

ALABAMA

The Alabama project is located on U.S. 84 highway in the eastbound direction, between Do than and Enterprise. The original pavement was constructed on borderline fine/coarse loamy soil, and had about 700 mm of a predominantly coarse soil aggregate mixture base, and about 97 mm of an HMA surface.

Alabama elected to extend its SPS–5 project by adding two supplemental test sections to study the performance of other rehabilitation treatments of interest; these are identified in table 42. All test sections had been monitored and the data collected were available to the Department of Transportation (DOT) for evaluation.

* RAP = Recycled asphalt pavement.

Preconstruction Monitoring

Pavement surface distress was collected on each section of the project before overlay construction. Each test section was manually surveyed. Low–severity longitudinal cracking was the predominant distress.

Surface profile was also conducted on the project, utilizing the SHRP/LTPP profilometer. Deflection measurements were obtained with the FWD for the evaluation of the structural capacity of each test section. Material samples were obtained in accordance with the LTPP criteria.

Construction Difficulties

Milling operations used a drum width of 2.2 m, which required the contractor to make two passes per lane. On the first day of construction, the pump to be used to transfer water from the tanker was inoperable. Milling continued without the benefit of water as a cooling agent. Milling with water as a coolant was used the next day.

On the third day of construction on section 010507, a temperature of 119 °C was observed before laydown and 104 °C after laydown, which was below allowable limits. On the sixth day of construction, it was noticed during the milling operations that the sections located between Stations 365+00 and 395+00 exhibited some fatigue–like longitudinal cracking in both wheel paths following the milling operation. In addition, the surface layer (about 25 mm thick) appeared to be lifting in sheets due to delamination. The milling machine pulled up large chunks of asphalt concrete about 150 mm by 90 mm in size. Consequently, the contractor was required to use more material from the U.S. 84 highway to compensate for the large particles that would have been screened out when preparing for the recycled mix at the plant.

Postconstruction Monitoring

Following construction, automated pavement distress surveys were to be obtained for all the test sections. Rod–and–level measurements were taken on the surface of all sections. In addition, the surface was profiled with the high–speed profilometer. Transverse profiles were taken using the automated method.

Structural capacity was evaluated using FWD measurements. Improvement in the structural capacity was noted in the overlaid sections, with the highest improvement in the sections with thicker overlays.

Coring was performed; 102–mm cores were obtained 15 m from approach and leave ends of each section following the outline in the material sampling plan.

Data Completeness

As shown in table 43, no thickness data were available from the L05B testing table. Thickness data from the SPS5_LAYER table were available, but were not reported here because L05B results are determinant values for the layer thickness.

Longitudinal profile monitoring was performed 6 months before overlaying, 6 months, and every 2 years after construction on all the sections except the control section, 014155.

FWD data were collected 6 months before and after construction on sections 014155 through 010503 and 010505. All other sections failed to meet either the preconstruction or the postconstruction monitoring requirements. Not all sections met the long–term requirements.

Distress monitoring was conducted 6 months before construction on all sections except section 010502. Only the control section was monitored for distress within 6 month after construction. The long–term monitoring requirement for distress was met for all sections after treatment.

Transverse profile monitoring was performed within 6 months after construction for all sections. Transverse profile was not measured on any section 6 months before construction. The long–term monitoring requirements for transverse cracking were met for all sections after treatment application.

No friction data were collected on any of the sections within 6 months before overlay. All core sections were monitored for friction data within 6 months after construction except the control, 014155, and the supplemental sections, 010563 and 010564. The long–term monitoring requirement was met for all sections after treatment.

No traffic data were available for this project except for the control section, which had 47 days of WIM and 2 years worth of monitored traffic data. There was one year with more than 45 days of AVC per year.

Table 44 summarizes the project testing data. It can be seen that only a small number of tests still needed to be conducted for the unbound base layers. However, almost no tests had been completed on the AC surface layers. Most of the available data were at Level E in the IMS database. No testing had been conducted on the overlay materials placed on this project.

ARIZONA

The Arizona SPS–5 project is in the dry–no–freeze environmental zone. It is located on Interstate 8, approximately 27 km west of Casa Grande, AZ. The original pavement was placed on a silty gravel with sand subgrade, had 361 mm to 447 mm of a granular base of soil aggregate mixture predominantly coarse, and 107 mm to 140 mm of HMA surface.

Arizona elected to extend its SPS–5 project by adding two supplemental test sections to study the performance of other rehabilitation treatments of interest. Each of these treatments is identified in table 45. All of these test sections had been monitored, and the data collected were available to the DOT for evaluation. However, these supplemental sections were not included in this investigation.

Preconstruction Monitoring

Monitoring data on rutting, roughness, and fatigue cracking were gathered on the sections before the application of overlays. At the time of construction, fatigue cracking was about 20 percent.

Surface profiling was conducted on the project utilizing the SHRP/LTPP profilometer. Deflection measurements were obtained with the FWD for the evaluation of the structural capacity of each test section. Material samples were obtained in accordance with the LTPP criteria.

Construction Difficulties

When paving the first of three lifts, the average temperature behind the paver was 107 °C, causing concern. There was some confusion about the calibration of the nuclear density for taking readings from the second lift of the overlays. An 80–kg/m³ correction was added to the density gauge. Later, the correction factor was determined to be 32 kg/m³. The compliance calculations were determined using 32 kg/m³ and subtracting the 80 kg/m³ only where data sheets noted that it had been added in.

Low stability was evidenced in the asphalt rubber concrete mix. The mix used in construction had a stability value of 49 kN. Milling on the minimum restoration sections was as high as 25 mm in some cases.

A 1.8–m milling width in one pass was used. This caused re–milling in several areas. Compacted density problems were encountered on the left lanes of sections 040507 and 040504.

Postconstruction Monitoring

Samples of the asphalt mix, granulated rubber, and reacted asphalt rubber binder material were taken. The AC–10 material was also sampled and sent to Central Materials for testing.

Data Completeness

As shown in table 46, thickness data were available from the L05B testing table. Thickness data from the SPS5_LAYER table were available, but were not reported here because the L05B results are the determinant values for layer thicknesses. It can be seen that the thicknesses were generally thicker than what was designed, especially with section 040506. This section’s thickness data were not yet at Level E in the IMS database.

Longitudinal profile data were collected within 6 months before and after overlaying on all the sections. The long–term monitoring requirement was not met except for section 040501.

FWD data were collected within 6 months before construction on all the sections. However, the requirements for postconstruction and long–term monitoring were not met for any of the sections.

Distress monitoring was conducted within 6 months before construction except for sections 040503, 040559, and 040560. Distress monitoring was not conducted within 6 months after construction. The long–term monitoring requirement for distress was met for all sections after treatment.

Transverse profile was not measured on any section within 6 months before or after construction. The long–term monitoring requirements for transverse cracking were not met for any section after treatment application.

No friction data were collected on any of the sections within 6 months before or after overlay. All core sections were monitored for friction data every 2 years after construction.

Approximately 5 years of traffic data and 290 days of WIM data were available for all sections. There were 4 years with more than 45 days of AVC per year.

Table 47 summarizes the testing data of the project. It can be seen that most of the required tests have been completed on this project. Most of the testing data are currently at Level E in the IMS database.

CALIFORNIA

The California SPS–5 project is in a dry–no–freeze environmental zone. It is located on Interstate 40 in San Bernardino County. The original pavement was constructed on poorly graded soil with silt, had 406 mm to 584 mm of predominantly coarse soil aggregate mixture subbase, 100 to 150 mm of cement aggregate mixture base, and 126 to 150 mm of AC surface.

California elected to extend its SPS–5 project by adding 13 supplemental test sections to study the performance of other rehabilitation treatments of interest; these treatments are identified in table 48. It should be noted that the control section, which was to receive no treatment, was also overlaid. All test sections had been monitored, and the data collected were available to the DOT for evaluation.

Preconstruction Monitoring

Preconstruction monitoring was performed on the above sections except two of the supplemental sections that were added before construction of the SPS–5 main sections. The preconstruction monitoring consisted of distress surveys, profile measurements, deflection measurements, and material sampling.

Distress surveys were performed using mostly automated surveys. Manual surveys were used when it was not possible to use automated surveys. Profile measurements were performed using a high–speed profilometer. Averaging the measurements over a moving 0.3–m interval provided the longitudinal profile of the travel lane for each section. Pavement deflections were measured using FWD. Two passes were applied: at mid–lane, and at the outer wheel path.

Sampling of materials was done by extracting 102–, 152–, and 305–mm diameter pavement cores; 152–mm auger probes; 305–mm bore holes, and 1.8–m by 1.2–m test pits to a depth of 305 mm below the top of the untreated subgrade.

Construction Difficulties

Overall, construction was not problematic, but some problems were encountered. There was segregation of the first lift and mat checking in the overlays that could be attributed to frequent starts and stops by the paver. There were also some problems during compaction of several sections. Several inconsistencies and incomplete work were encountered in the milling operations on sections 060502, 060503, and 060509. Slipping of the paver occurred on supplemental sections 060560 and 060561 resulting in torn pavement reinforcing fabric, which in some areas was removed, but not replaced.

Postconstruction Monitoring

The postconstruction monitoring performed on the California SPS–5 site consisted of a distress survey, profile measurements, deflection measurements, and 102–mm core sampling of the overlay material. The cores were taken 6 m from the beginning and end of each section.

Data Completeness

Table 49 shows the summary data pertaining to the California SPS–5 project in the IMS database, where it can be seen that the actual thicknesses for the core SPS–5 sections in California were substantially higher that the design values. It is also evident that the control section was overlaid. The construction report notes that a 58– to 71–mm recycle mix overlay was applied to the control section.

Longitudinal profile data were collected within 6 months before construction. However, even though the construction report mentions that the data were collected within 6 months after construction, the data in the IMS database do not show that. The frequency of the longitudinal profile data collection met the long–term monitoring frequency requirement.

FWD data were collected within 6 months before construction except for sections 060501, 060559, and 060564 through 060569. There were no data recorded within 6 months after construction. The data collection met the long–term monitoring requirement except for sections 060559, 060567, 060568, and 060571.

Distress surveys were conducted every 2 years after construction except for section 060560; however, no data were recorded for distress surveys within 6 months before and after construction.

Transverse profile data were collected within 6 months before construction and every 2 years after construction; however, there were no data within 6 months after construction.

The frequency of the friction data collection did not meet any preconstruction, postconstruction, or long–term requirements.

Only 1 year of traffic data was available, which includes 32 days of WIM and less than 45 days of AVC.

Table 50 summarizes the availability of materials testing data for the California SPS–5 project. It can be seen that there was a serious deficiency in the testing data for both the preconstruction and postconstruction data. In addition, none of the tests conducted were at Level E in the IMS database.

*CTB = cement–treated base

COLORADO

The Colorado SPS–5 project is in the dry–freeze environmental zone. The project is located on Interstate 70 in Lincoln County. The original pavement rested on clayey soil mixed with coarse material ranging from sand to gravel. The original pavement had an AC surface thickness that ranged from 55 mm to 170 mm. The AC surface thickness rests on a 25 mm to 99 mm dense graded, hot laid, emulsion mixture treated base.

Colorado extended its SPS–5 project by adding two supplemental test sections to study the performance of other rehabilitation treatments of interest. Each of these treatments is identified in table 51. The SPS–5 control section also received a rut level–up course, although it was to receive no treatment. All of these test sections had been monitored, and the data collected were available to the DOT for evaluation.

Preconstruction Monitoring

Samples were collected according to the testing plan. The sampling was done outside the 152–m test sections. A distress survey, deflection, and profile measurements were done 3 months before rehabilitation.

Construction Difficulties

While treatment was not scheduled for the control section, the severity of its rutting caused a hydroplane concern; therefore, a rut level–up was placed on that section. No other construction difficulties were reported for the Colorado SPS–5 project.

Postconstruction Monitoring

Cores 162 mm in diameter were taken in the approach and leave areas around each test section after construction. The drilling locations were different because of weather conditions. Twenty additional 102–mm cores were taken at section 080504 for additional study at Pennsylvania State University. Profile, deflection, and distress survey measurements were performed less than one year after construction.

Data Completeness

Table 52 shows a summary of the key elements for the Colorado SPS–5 project. Layer thicknesses reported in the IMS were substantially larger than the design values. In addition to the overlay, a rut level–up layer of 33 mm was placed on the minimum surface preparation sections.

Longitudinal profile monitoring was performed within 6 months before and after treatment, and then at 2–year intervals after construction, thus meeting the data–collection requirements.

Deflection data were collected within 6 months before and after construction, and at a frequency of every 2 years afterwards.

Distress surveys for the Colorado SPS–5 project were collected within 6 months before and every 2 years after the construction of the overlays. However, surveys were not taken within 6 months after the placement of the treatments.

Transverse profile data were collected within 6 months before and after the application of treatments; however, the long–term frequency requirements were not met.

Friction data were collected at a 2–year interval after the placement of the treatments, but not within 6 months before or after overlays were placed.

For the control section, there were 1,181 days of WIM and 4 out of the 5 years’ worth of monitored traffic data had more than 45 days of AVC per year. For the treated sections, there were 1,058 days of WIM data. Among the 4 years of traffic data available for this project, 3 had more than 45 days of AVC per year.

Table 53 shows a summary of the testing material data collected on the Colorado SPS–5 project. It can be seen that most of the preconstruction testing had been completed. In addition, all of the available data were at Level E in the IMS. A similar observation can be made about the postconstruction testing. Only a few tests still needed to be done on the overlay AC and extracted aggregate, with the majority of the available data at Level E.