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Trichloroethylene is a solvent currently used by the Florida Department of Transportation (FDOT) and many state highway agencies for separation of asphalt binders from asphalt paving mixtures in their quality control programs. However, it has been proved that trichloroethylene contributes to ozone depletion, and it is also known to be a carcinogen. The goal of the present study was to determine whether a more environmentally sound and less hazardous solvent could be used for this purpose. The solvent investigated is an n-propyl bromide with the trade name EnSolv. Preliminary studies show that it is safer than many other solvents available today. The study was performed to determine whether EnSolv could be a substitute for trichloroethylene without changing current testing methods. The tests performed included the asphalt solubility test, extraction and recovery of asphalt binders from mixtures, and penetration and viscosity tests with the recovered binders. The results of the study showed that EnSolv could be a suitable replacement for trichloroethylene. In addition, EnSolv could also be recycled and reused in the extraction and recovery procedures.

Frequently, when mass concrete is placed directly on top of a soil layer, an insulation layer is not used at the bottom of the concrete. The rationale for this practice is that the soil on which the concrete is placed is already an insulating material. This study investigated the question of whether the absence of an insulating layer between the mass concrete and the soil may cause a problem with cracking of the concrete at an early age. A three-dimensional finite element model was used for this investigation. The typical soil condition in Florida, where the ground-water level is high, was considered. The soil layer beneath the concrete was modeled to simulate realistic heat transfer between the concrete and the soil. To validate the developed model, temperature development in a bridge pier footing constructed in the field in Florida was compared with the computed temperature distribution from the finite element model. The results showed that the temperatures predicted by the model closely agreed with those measured in the field. A parametric analysis was also conducted to determine the effects of insulation on the temperature distribution, induced tensile stresses, and cracking risk in the concrete. From the thermal cracking analysis for the monitored footing, it is concluded that full insulation with adequate thickness (a 63-mm-thick blanket at the top, 63-mm plywood panels at the sides, and a 63-mm polystyrene foam board at the bottom) should be used to reduce the temperature differentials and prevent early-age cracking in concrete.

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