Use of Thermal Integrity Profiling (TIP) in Drilled Shaft Evaluation

Thermal Integrity Profiling (TIP) methods have emerged as a viable concrete integrity test method alternative to crosshole sonic logging (CSL). The objective of this study was to evaluate TIP methods for potential implementation on MoDOT drilled shaft projects. 

The study included a review of experience from previous research and project applications as well as collection of new data from a MoDOT project application. Together, the previous studies and the new research indicate TIP and CSL are generally complementary, with TIP more effective for identifying defects outside the reinforcing cage and weak concrete defects and CSL more effective for identifying defects within the reinforcing cage and soft bottom conditions. However, the results of this study indicate soft bottom conditions may be detectible with TIP methods, especially if temperature versus time records at the bottom of the shaft are evaluated. 

This research also included implementation of fiber optic methods for collecting TIP data. Laboratory and field results indicate fiber optic methods result in similarly accurate temperature results compared with conventional TIP, although practical limitations generally mean the fiber optic methods do not produce as complete of a time record. Cost data was also analyzed, indicating conventional TIP may result in cost savings compared to CSL, which is primarily a result of savings associated with remote data collection for many TIP projects. Finally, recommended specifications for MoDOT implementation of TIP methods were developed. The proposed specifications are included as an appendix.

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Report number: cmr 22-002
Published: January 2022
Project number: TR202015
Authors: Andrew Boeckmann, R. Andrew Yeskoo, and Paul Axtell

Performing organization: Dan Brown and Associates

Compacted Concrete Pavement

The main objective of this project was to evaluate construction issues and characterize the long-term performance of compacted concrete pavement (CCP). Three CCP test cells were designed and constructed in Scott County, Missouri, as part of a larger construction project. The total pavement length was 42 ft for the three cells. Cell 1 and Cell 2 were prepared without fibers and had a length of 15 and 12 ft, respectively. Cell 3 was prepared with 5 lb/yd3 (pcy) of synthetic fibers and had a length of 15 ft. The moisture content of the concrete was kept between 5% and 6%, and the water-to-cementitious material ratio was maintained between 0.31 and 0.38. 

Test results showed that the incorporation of fibers enhanced the mechanical properties (compressive and flexural strengths) of CCP mixtures when proper compaction was provided, as in the case of cast-in field samples. Also, fibers changed the flexural failure mode of saw-cut and cast-in-field CCP samples from brittle to ductile failure. The incorporation of fibers had a restraining effect on the drying shrinkage of CCP mixtures. The use of fibers did not have a significant effect on the performance of CCP mixtures, as shown from the falling weight deflectometer (FWD), truck loading tests and curling and warping. This can be mainly related to the extremely dry consistency of the CCP mixtures (Vebe consistency > 60) that can hinder bond strength in the interfacial transition zone with the matrix. This was more accentuated in the saw-cut samples from the paved CCP as the paving process in the field did not provide enough compaction. As for the size of slabs, results showed that the size of CCP slabs was more effective in the curling and warping measurements. The slab with longer length (15 ft) showed higher variations in curing and warping along the diagonal, transverse and longitudinal lengths over time. 

Therefore, the use of fibers in CCP can be recommended provided that the CCP mixture has adequate workability and sufficient compaction energy applied during construction.

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Report number: cmr 22-001
Published: January 2022
Project number: TR201904
Authors: Kamal H. Khayat, Nima Farzadnia, and Ahmed Abdelrazik

Performing organization: Missouri University of Science & Technology