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| FHWA > Engineering > Pavements > Concrete > CPTP Status Report |
CPTP Status Report - Task 65 Engineering ETG Review CopyAppendix B - CPTP Project DetailsTask 56-A (99) - TFHRC PCCP Laboratory Studies: Development of Standard Test for Concrete Coefficient of Thermal ExpansionContracting Dates: 1999 to 2007 Project Goals/Objectives: The goals of this project are to:
Background: CTE is a characteristic determined by the LTPP program to have a potential influence on the performance of pavements. As a result, the concrete laboratories at the Turner-Fairbank Highway Research Center were assigned the task of developing a standard test for this property, since none existed in either AASHTO or ASTM. Status: A standard CTE test has been developed and finalized. It involves: sawing the cores to a standard length (178 mm/ 7 in.); grinding the ends parallel; soaking the cores to reach SSD condition; mounting the core in a measuring frame using an LVDT; putting the setup in a controlled temperature water bath; and obtaining exact specimen length change and temperature change due to a change in temperature of the bath of 40 C. This test is now AASHTO Provisional Standard TP-60-00, as listed in the 2000 volume. At least partially because of this work, the new 2002 AASHTO design guide will include CTE of the concrete as one of the input variables. Tests continue to be conducted on the LTPP cores, with an estimated 4 years of testing remaining. New water baths were purchased to increase testing throughput. Available Reports/Articles/Presentations: Folder - Guidelines for the Use of Lithium to Mitigate or Prevent ASR. Task 56-B (99) - TFHRC PCCP Laboratory Studies: Concrete Mixture Optimization Using Statistical Mixture MethodsContracting Dates: 1999 to 2001 Project Goals/Objectives:
Background: High-performance concrete (HPC) mixtures typically contain at least six component materials and may be required to meet several performance criteria simultaneously. While the ACI 211 guide for proportioning concrete mixtures and other procedures are good starting points for concrete proportioning, they do not provide information on the optimal proportions for meeting several performance criteria at the same time. As a result, trial and error, considering one factor at a time is the usual process. This approach can be inefficient, costly, and may not result in the best combination of materials. Statistical procedures have been developed for optimizing mixtures in other industries. The feasibility of applying this technique to concrete needs to be explored. Status: Laboratory work and interactive Web site software development have been completed. The interactive Web site called Concrete Optimization Software Tool and user's guide are accessible online at http://ciks.cbt.gov/cost. The software will also be installed in the FHWA MCL and on the TFHRC Web site. Final project report and a user's guide were submitted for editorial review in January 2003. Available Reports/Articles/Presentations: Optimizing High-Performance Concrete Mixtures Using Statistical Response Surface Methods by Marcia J. Simon, Eric S. Lagergren, and Leif G. Wathne, June 1999. Task 56-C (99)?TFHRC PCCP Laboratory Studies: Freeze-Thaw Durability of Concrete with Marginal Entrained Air ContentContracting Dates: 1999 to 2003 Project Goals/Objectives:
Background: An adequate entrained air void system in concrete is considered necessary for resistance to distress due to freezing and thawing. Typical air void parameters are 6 percent air, a specific surface greater than 600, and a spacing factor of 0.008 in or less. However, there is evidence that some concretes not meeting these criteria may be freeze-thaw durable, and there is debate as to whether some HPC with sufficiently low water-cementitious ratio require air entrainment. The SHRP project on F/T durability proposed a modified testing procedure using terry cloth covers, and use of the "quality factor" for predicting the performance of concrete F/T specimens. These modifications are being investigated to assess their usefulness in improving freeze-thaw testing. Status: Phase I is complete. In this phase, concretes with air contents of approximately 3 percent withstood 300 cycles of freeze-thaw testing. The SHRP terry cloth procedure was in most cases as severe as Procedure A, and is less variable than Procedure B. Mass loss was considerably greater in Procedure A (due to scaling). Phase II involves testing of concretes with air content ranging from 2.5 to 4.5 percent and w/c ratios of 0.40 to 0.50 with two different types of AEA. The first part of Phase II is complete and results indicate similar results for freeze-thaw durability. Further data analysis is underway to assess relationship of air void parameters to durability and use of quality factor for assessing damage. Because of continuing problems with steel containers and difficulty obtaining new ones, a study comparing terry cloth and containers at a range of air contents (2.7 to 4.7 percent) was performed to assess the relative severity of testing. If testing results are comparable, further testing will be conducted using terry cloth in lieu of containers. The comparison study was completed in December, 2002. The results indicate comparable durability factors, with terry cloth having slightly higher values, except for the case of non-air entrained concrete, where terry cloth was more severe. Specimens in containers experienced moderate to severe scaling (2-3% mass loss, typically) regardless of air content. The scaling probably had some effect on the durability factor. Surprisingly, nearly all of the air-entrained test beams, even the 2.7 percent air mix, had durability factors above 80% after 300 cycles. This result corroborates the Phase I results. Further investigation of the air void parameters of these mixes is underway, along with analysis of the quality factor from frequency response data. A set of tests using the Air Void Analyzer to determine air void parameters of the fresh concrete is planned for spring, 2003. Available Reports/Articles/Presentations: Task 56-D (99) - TFHRC PCCP Laboratory Studies: Development of Alkali-Silica Reactivity Mix-Specific Test MethodContracting Dates: 1999 to 2003 Project Goals/Objectives: To identify a fast, reliable test for assessing ASR potential of concrete mixtures. Background: There is currently no rapid test method that is claimed to evaluate the ASR susceptibility of concrete mixtures. ASTM C1260 specifically states that it is to be used to assess aggregates and not combinations of aggregates and cementitious materials (although some researchers have investigated its use for that purpose). The concrete prism test developed in Canada (ASTM C1293) is more realistic, in that it tests concrete rather than mortar, but it can take a year or more to perform. Other methods have been suggested or tried, but are not recommended due to limited data. Status: Phase I results indicate that the use of different cements can have a significant effect on the expansion measured in C1260, even if the cements meet the criteria set forth in the test method. It is suspected that MgO in the cement could be the cause. A paper documenting this work was presented at the 11th International Conference on Alkali-Aggregate Reactivity in June of 2000. Phase II is underway. Tests are being performed for one year at 38C, for 3 months at 60 C, and for three months at 60 C using modified prisms with longitudinal holes to allow easier moisture ingress (developed at UNH). Variables include w/c (0.4 to 0.5), percent Class F fly ash replacement (0 to 30), and percent recommended lithium dosage (0 to 100). Testing at 38 C began in August 2002. Currently, repeat mixes of 38 C specimens are being performed because of concerns with some early readings. Testing at 60 C has been delayed due to equipment problems with the environmental chamber, which will be resolved by mid-March, 2003. Casting and testing of prisms at 60 C will begin in March 2003. Available Reports/Articles/Presentations: Task 56-E (99) - TFHRC PCCP Laboratory Studies: Variation of Shrinkage Potential of Portland Cement ConcreteContracting Dates: 2002 to 2004 Project Goals/Objectives: To assess the shrinkage behavior of PCC paving mixtures and identify mixtures which minimize shrinkage and the associated cracking tendency. Background: Uncontrolled cracking in jointed concrete pavements is an area of concern when it comes to providing long service life without the need for premature repair and rehabilitation. One of the primary properties of the concrete influencing the occurrence of cracking is the amount of shrinkage that the concrete undergoes. It is known that the total shrinkage experienced by PCC depends on a number of factors, such as the aggregate volume fraction, cement properties, and curing environment. Further study is needed to investigate the effect of the combination of various concrete components and curing regime on concrete shrinkage. Status: Equipment has been assembled to conduct restrained and unrestrained shrinkage tests and evaporable/non-evaporable water measurement. Installation of temperature and humidity control for the shrinkage lab was delayed and is expected to be completed by mid-March, 2003. Once the controlled environment room is operational, materials will be obtained and planning/testing will begin. Available Reports/Articles/Presentations: Task 56-F (99) - TFHRC PCCP Laboratory Studies: Evaluation of the Workability Test and the Workability of Concrete Paving MixturesContracting Dates: 2002 to 2003 Project Goals/Objectives:
Background: The slump test measures only part of the concrete properties that influence workability, which is the yield stress. In order to fully define workability the plastic viscosity of the concrete must also be known. Many concrete Rheological devices have been developed, however none are applicable to the relatively stiff slip form paving concrete. The U.S. Army Corps of Engineers (USACE) recently developed a workability-measuring device for FHWA. The vibrating slope apparatus (VSA) quantifies the workability by measuring the time it takes for a measured mass of concrete to move out of the chute under certain vibration energy. Status: The three new VSAs, with updated electronics and software, were completed in December 2002. Two VSAs were loaned to the University of Texas and Iowa State University for evaluation. The remaining VSA is being evaluated further at TFHRC in this study, which will include assessment of test factors (concrete slump, chute angle, and vibration force), test procedure modifications, and analysis and interpretation methods. Use of FRP instead of steel for the chute (to decrease weight and thus increase effect of vibrator) will also be investigated. Available Reports/Articles/Presentations: Task 57 (99) - Computer-Based Guidelines for Concrete Pavements (HIPERPAV II)Contracting Dates: 2000 to 2004 Contract Amount: The original contract amount was $745,250. A subsequent modification to the contract added Task G (workshops and technical support) and Task H (further improvement of the HIPERPAV-II software), increasing the contract amount to $953,343 and extending the period of performance to January 31, 2004. Contractor: Transtec Group, Inc. Project Goals/Objectives: The improved and expanded software (HIPERPAV II) program includes modules for prediction of JPCP long-term performance as a function of early-age behavior and early-age behavior of continuously reinforced concrete pavements. Two recent completed FHWA studies have also been incorporated to provide capabilities for optimization of concrete mix designs to meet specific performance criteria, and predict early-age behavior of dowel bars in rigid pavements. Background: Previously, FHWA developed a computer program, HIPERPAV, to provide guidance to the pavement engineer in the selection of materials and mixture design, pavement design, and construction procedures to avoid early-age cracking in JPCP. The purpose of this project is to investigate and provide guidance on the performance of JPCP beyond the first 72 hours, and to investigate and provide guidance on the early-age behavior of CRCP. Status: Work in progress. Three workshops were conducted in Pennsylvania, Iowa, and Michigan. The modifications and improvements are being made to the HIPERPAV II software program to reflect feedback received from the Technical Group. The contract completion date is January 31, 2004. Available Reports/Articles/Presentations: FHWA RFP Objectives, Scope of Work and Proposed Work Plan; Contractor's Work Plan Task 58-A (98) - The Use of Precast Concrete Panels to Expedite Highway Pavement ConstructionContracting Dates: 1999 to 2000 Project Goals/Objectives: To investigate the feasibility of using precast concrete technology as a means to expedite concrete pavement construction. Background: Precast concrete construction methods have been developed which are viable alternatives in applications such as buildings and bridges. One of the primary benefits of precast components is the speed of construction. Precast elements can be cast in controlled conditions at a precasting yard, far in advance of when they will be needed, then stockpiled and transported to the jobsite as necessary. Allowing time for concrete to cure before opening to traffic is a time-consuming phase of concrete pavement construction. The use of precast elements would eliminate this step while optimizing curing for the precast slabs. Status: The feasibility study has been completed; the results are published as Center for Transportation Research Report Number 9-1517-1. The proposed panels are to be cast with continuous shear keys in the edges to aid with alignment when assembled. The panels are pre-tensioned in the transverse direction during fabrication, and post-tensioned in the longitudinal direction during construction. A follow-up project to work with several States to conduct field trials is underway. Available Reports/Articles/Presentations: FHWA RFP Objectives, Scope of Work and Proposed Work Plan; Contractor's Work Plan Task 58-B (98) - The Use of Precast Concrete Panels to Expedite Highway Pavement Construction, Phase 2: Pilot StudiesContracting Dates: 2000 to 2002 Project Goals/Objectives: To investigate the feasibility and demonstrate use of precast concrete technology as a means to expedite concrete pavement construction. Background: Precast concrete construction methods have been developed which are viable alternatives in applications such as buildings and bridges. One of the primary benefits of precast components is the speed of construction. Precast elements can be cast in controlled conditions at a precasting yard, far in advance of when they will be needed, then stockpiled and transported to the jobsite as necessary. Allowing time for concrete to cure before opening to traffic is a time-consuming phase of concrete pavement construction. The use of precast elements would eliminate this step while optimizing curing for the precast slabs. Status: Pilot project completed on I-35 frontage road in Georgetown, Texas, November 2001. Pilot project on I-10 in California under construction in October 2002. UPDATE: Final report expected by mid -2003. Paper prepared for 7th International Conference on Concrete Pavements, Orlando, FL 9/2001. Paper prepared for TRB Annual meeting, 2002, Paper prepared for PCI conference, October 2003. Paper prepared for TRB Annual Meeting, 2003 Available Reports/Articles/Presentations: FHWA RFP Objectives, Scope of Work and Proposed Work Plan; Contractor's Work Plan Task 58-C (98) - The Use of Precast Concrete Panels to Expedite Highway Pavement Construction, Phase 3: Demonstration ProjectsContracting Dates: 2003 to 2004 Project Goals/Objectives: To demonstrate the use of precast, post-tensioned concrete pavements as a means to expedite concrete pavement construction. Background: Precast concrete construction methods have been developed which are viable alternatives in applications such as buildings and bridges. One of the primary benefits of precast components is the speed of construction. Precast elements can be cast in controlled conditions at a precasting yard, far in advance of when they will be needed, then stockpiled and transported to the jobsite as necessary. Allowing time for concrete to cure before opening to traffic is a time-consuming phase of concrete pavement construction. The use of precast elements would eliminate this step while optimizing curing for the precast slabs. Status: Projects being developed in California and Missouri. In addition a contractor is preparing technical summary report on HPCP: Precast Pavement Technology due about April 30, 2004. Available Reports/Articles/Presentations: FHWA RFP Objectives, Scope of Work and Proposed Work Plan; Contractor's Work Plan
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This page last modified on 05/01/07 |
