High Performance Concrete Pavements
CHAPTER 16. IOWA 7 and MARYLAND 2 (Implementation of TEMP)
The most common uses of the Total Environmental Management for Paving (TEMP) system is to predict the critical time to open concrete pavements to traffic and to determine the appropriate time for joint sawing activities (Transtec 2002). Concrete strength development and pavement opening times are computed using maturity concepts in which the opening time can be predicted based on the past (known) and future (predicted) concrete temperatures. Maturity methods have been used effectively for a number of years. The key advantages of the TEMP system over the state-of-the-practice are automation and prediction. At a minimum, a TEMP System is comprised of concrete temperature gauges as well as a computer running the TEMP System software. An optional portable weather station can be included to further enhance the predictive ability of the software.
In 2003, a cooperative project was initiated to implement the TEMP system in the field. Three candidate implementation sites, two in Iowa and one in Maryland, have been identified for this project. The results from this project will help an agency or contractor better utilize concrete maturity data and improve the efficiency and quality of concrete paving.
The objectives of this project include proof testing in the field as well as associated implementation activities of the TEMP system. These objectives can be categorized as follows (Turner and Ruiz 2003) :
- Demonstrate an automated maturity data collection system that automatically collects and relays maturity data in the field.
- Demonstrate an automated maturity data management and reporting system that automatically catalogs maturity data in a fashion suitable for easy reporting and interpretation by the practitioner.
- Demonstrate a system that performs real-time predictions of future concrete strengths and time of opening to traffic.
Project Design and Layout
Up to three implementation sites are required for this project, which have been tentatively identified as (Turner and Ruiz 2003):
- US 151 in Jones County, Iowa. This project is a four-lane relocation and new construction on a new alignment. The total length of the project is 9.93 km (6.17 mi) from North of Monticello, Iowa, to Cascade, Iowa. The pavement cross section is a 240-mm (9.5-in.) JPCP on a 260-mm (10.2-in.) granular base. The inside and outside lanes will be 3.6 m (11.8 ft) and 4.2 m (13.8 ft) wide, respectively. Perpendicular transverse joints will be doweled and spaced at 6-m (20-ft) intervals. The pavement will have granular shoulders.
- County roads, including 320th Street in Washington County, Iowa. This project is a combination of four individual sections in Washington County. Two sections (6.50 and 2.75 km [4.04 and 1.71 mi] long) are 6.7-m (22-ft) wide JPCP on 102-mm (4-in.) of rubblized concrete. The new concrete layer varies from 254 mm (10 in.) at the edges to 178 mm (7 in.) at the centerline. The pavement will have skewed and doweled transverse joints at a spacing of 4.6 m (15 ft) and will have granular shoulders. A third, 4.36-km (2.71-mi) long section follows the same concrete surface thicknesses but will be constructed on an existing granular surfaced road. A fourth section will be approximately 12.9 km (8 mi) long and will follow the same design for the concrete surface layer, but will be constructed as whitetopping (on existing asphalt) or on granular material.
- Frederick, Maryland. Details on this project are still being collected.
Temperature monitoring sensors (iButtons™) will be installed into fresh concrete during paving. IButtons™ will be installed at the mid-depth of the pavement and 0.3 to 0.9 m (1 to 3 ft) from the outside edge and transverse joint with intervals typically between 30.5 and 305 m (100 and 1000 ft) (Turner and Ruiz 2003).
State Monitoring Activities
Concrete temperature and strength as well as weather conditions (e.g., temperature, wind speed, and relative humidity) will be monitored using the TEMP System for 3 to 4 days following placement (Turner and Ruiz 2003).
No preliminary results or findings are available at this time.
Point of Contact
Iowa Department of Transportation
800 Lincoln Way
Ames, IA 50011
The Transtec Group. 2002. Technical Work Plan for Implementation of a Total Environmental Management for Paving (TEMP) System. The Transtec Group, Inc., Austin, TX.
Turner, D. J., and J. M. Ruiz. 2003. Final Work Plan for Implementation of a Total Environmental Management for Paving (TEMP) System. The Transtec Group, Inc., Austin, TX.