Date Approved

7-12-2021

Embargo Period

7-13-2021

Document Type

Thesis

Degree Name

M.S. Civil Engineering

Department

Civil and Environmental Engineering

College

Henry M. Rowan College of Engineering

Advisor

Yusuf Mehta, Ph.D., P.E.

Committee Member 1

Cheng Zhu, Ph.D.

Committee Member 2

Gilson Lomboy, Ph.D.

Keywords

Cold regions, Pavement testing

Subject(s)

Pavements--Performance

Disciplines

Civil and Environmental Engineering

Abstract

A comprehensive laboratory testing plan was conducted as part of this project to select two frost-susceptible soils for use in constructing three full-scale test strips. A total of 16 soils were obtained from various suppliers in NJ and were evaluated to determine their frost-susceptibility. The evaluation included conducting sieve analysis, hydrometer analysis, and specific gravity. Using these measures, two soils were selected (namely, Soil #2 and Soil #13) for constructing the test strips. The properties (Atterberg Limits, moisture-density relationships, California bearing ratio (CBR), Resilient Modulus among others) were determined through a laboratory testing plan. In addition, this study involved constructing three full-scale test strips (as one section) at the CREATEs full-scale testing facility. The first test strip was constructed using a typical NJ HMA mix, a typical dense graded aggregate base (DGA), and Soil #2 used as the subgrade. Test Strip II was constructed using the same HMA mix, a blend of DGA and Soil #13 (one to one), and Soil #2 as the subgrade layer. Test Strip III had a blend of DGA and Soil #13 for the base layer and a one-to-one blend of Soils #2 and #13 for the subgrade layer. All three test strips were evaluated using the HWD on weekly basis. Test Strip I also included a thermal conductivity probe that is capable of measuring moisture content, temperature, and thermal conductivity at varying depths in the base and subgrade layers.

Based on the laboratory and full-scale testing, the following main conclusions were drawn: 1. While Soil #2 (SC) showed a low Resilient Modulus value (50 MPa), Mr was not measured for Soil #13 (ML) due to failure of samples during testing. A Mr value was estimated for Soil #13 using an empirical relationship with CBR results. All in all, the Mr values for both soils (estimated and measured) indicate that they are both weak. 2. The base layer (Strip I) has shown a constant thermal conductivity trend, with some variations during October, November and December. The subgrade layer; however, had a more constant thermal conductivity values during January and beginning of February, while for the rest of the other months, fluctuations can be observed. Even if small (approximately 0.1 BTU/ft.-hr-F), these spikes were recorded often, when change in moisture content was seen. Although the moisture content inside the subgrade layer was lower and more constant compared to the base layer, the thermal conductivity values of the subgrade soil (Soil #2) had a higher sensitivity to moisture changes. Thus, Soil #2 showed a higher thermal conductivity potential than the DGA material. 3. The back-calculated moduli values shows that Test Strip I had the highest structural integrity (i.e., high and least variable moduli values) of all three strips. This is the case because this strip was constructed with typical paving materials (i.e., HMA surface course and DGA base layer) and Soil #2 as the subgrade layer.

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