State departments of transportation (DOTs) are increasingly using trenchless strategies to rehabilitate and repair aging infrastructure within urbanized areas. Performing pipe repairs to existing systems, as compared to pipe replacement, significantly reduces the construction time and maintenance of traffic operations and roadway reconstruction. This provides increased public safety and cost savings to the state DOTs. One of the most common pipe rehabilitation methods is cured in-place pipe (CIPP) liners. CIPP liners are a trenchless technology that provides a method to structurally rehabilitate existing pipes and conduits with minimal impact to the traveling public. The liner consists of a resin-impregnated material that is inserted into the existing damaged host pipe.
Currently, there is insufficient information available to ensure the CIPP liner possesses the properties and durability of the expected life span of this repair strategy. Pipe owners and CIPP contractors need design guide and testing standards for CIPP pipe rehabilitation repair.
The objectives of this research are to develop (1) an AASHTO guide for design and installation of CIPP liners for structural rehabilitation of existing pipelines and conduits including design examples to demonstrate the application of the guide and (2) an AASHTO standard practice for test methods for CIPP liner technology. The AASHTO guide for design of CIPP liners shall be based on the Load and Resistance Factor Design (LRFD) method.
At the minimum, the AASHTO standard practice for CIPP liner technology shall include:
- a laboratory test method to verify the proposed structural capacity of rehabilitated conduits using CIPP liner technology,
- an accelerated laboratory test method to predict liner service life, and
- a laboratory test method for the different materials for liner and resin, and curing methods.
Accomplishment of the project objectives will require at least the following tasks.
Task descriptions are intended to provide a framework for conducting the research. The NCHRP is seeking the insights of proposers on how best to achieve the research objectives. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objectives.
Task 1. Conduct a literature review of relevant research to identify the state-of-the-practice related to CIPP liner repair technology. The review shall include published and unpublished research conducted through the NCHRP; FHWA; and other national, international, state, and pooled-fund sponsored research.
Task 2. Synthesize the literature review to identify the knowledge gaps for design, installation, and testing methods of CIPP liner repair technology. These gaps should be addressed in the proposed AASHTO guide and standard practice or in the recommended future research as budget permits.
Task 3. Propose analytical and testing programs, to be executed in Phases II and III, to achieve the project objectives. At a minimum, the programs should consider the following:
- structural properties,
- different pipe diameters,
- design service life,
- materials properties of liner and resin,
- existing standards,
- sampling and laboratory test methods,
- installation process including preparation and curing methods, and
- testing procedures to develop the standard practice.
In addition, testing specimens for design verification should (1) replicate in situ condition and (2) consider the scale effect on the accuracy of the results.
Task 4. Provide an annotated outline of the proposed guide and the CIPP liner repair technology including examples to demonstrate the application of the proposed deliverables.
Task 5. Prepare Interim Report No. 1 that documents Tasks 1 through 4 and provides an updated work plan for the remainder of the research. This report must be submitted no later than 4 months after contract execution. The updated work plan must describe the process and rationale for the work proposed for Phases II though IV.
Note: Following a 1-month review of Interim Report No. 1 by the NCHRP, the research team will be required to meet in person with the NCHRP project panel to discuss the interim report. Work on Phases II though IV of the project will not begin until authorized by the NCHRP. Phase I shall be limited to $40,000.
PHASE II—Analytical Program
Task 6. Execute the analytical program according to the approved Interim Report No.1.
Task 7. Finalize the testing program work plan. Describe how the testing results will be utilized to achieve the research objectives.
Task 8. Develop the LRFD method for the design of CIPP liners.
Task 9. Prepare Interim Report No. 2 that documents the results of Tasks 6 through 8 and provides an updated work plan for the remainder of the project. This report is due no later than 8 months after approval of Phase I. The updated plan must describe the work proposed for Phases III and IV.
Note: Following a 1-month review of Interim Report No. 2 by the NCHRP, the research team will be required to meet in person with the NCHRP project panel to discuss the interim report, if necessary. Work on Phases III and IV of the project will not begin until authorized by the NCHRP. Phase II shall be limited to $100,000.
PHASE III—Testing Program
Task 10. Execute the testing program according to the approved Interim Report No.2.
Task 11. Validate the analytical program based on the testing results and update accordingly.
Task 12. Develop the AASHTO guide and standard practice based on the research results with the examples.
Task 13. Prepare Interim Report No. 3 that documents the results of Tasks 10 through 12 no later than 15 months after approval of Phase II. The updated work plan must describe the work proposed for Phase IV.
Note: Following a 1-month review of Interim Report No. 3 by the NCHRP, the research team will be required to meet in person with the NCHRP project panel to discuss the interim report, if necessary. Work on Phase IV of the project will not begin until authorized by the NCHRP. Phase III shall be limited to $200,000.
PHASE IV—Final Products
Task 14. Revise the draft AASHTO guides and standard practice considering the NCHRP’s review comments. The revised versions are due no later than 2 months after approval of Phase III.
Task 15. Prepare final deliverables including: (1) the proposed AASHTO guide and standard practice that reflect consideration of the NCHRP’s review comments, (2) a final report that documents the entire research effort, and (3) a stand-alone technical memorandum titled “Implementation of Research Findings and Products.” See Special Note D for additional information.
Note: Following receipt of the draft final report, the remaining 3 months shall be for NCHRP review and comment and for research agency preparation of the revised final report. Phase IV shall be limited to $30,000.
STATUS: Research in progress