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To study the effectiveness of sealants in reducing chlorides and water intrusion into pavement joint openings, nine 122 x 91.5 x 20.3 cm concrete slabs were fabricated. One slab was cast without a joint and was used as a control; two were cast with non-sealed joints, and the other six were cast with joints which were sealed, after slabs were cured, with either type “A” or type “B” sealant, which are one-component rigid pavement joint sealants. Three dowel bars were installed below the joint at the mid-thickness of each slab, used for load transfer. Two types of dowels were used: epoxy-coated and uncoated. The joints were formed by installing removable styrofoam prior to concrete casting. A crack was formed from the bottom of the joint to the slabs's bottom, through the cross section of the slab to simulate field conditions; construction paper was used for this purpose. To accelerate the possibility of dowel bar corrosion and to examine pavement joint sealant effectiveness in abating chloride intrusion, the slabs were exposed to alternate ponding cycles of 6% (by weight) sodium chloride solution (3-days ponding and 4-days dry). The corrosion progress was monitored by measuring corrosion current density (icorr) using a Three-Electrode Linear Polarization (3LP) device. Also, chloride contamination was measured by collecting powdered concrete samples from each slab at four different depths to allow for chloride penetration profile assessment. The collected samples were analyzed to measure the percent of chloride diffused into the concrete and compared to background chloride percent in concrete. An analysis of results provided for the evaluation of icorr and chloride contents over a period of 18 months. The results show that the unjointed slab has higher resistance to chloride penetration, followed by jointed slabs sealed with type “A” sealant, then jointed slabs sealed with type “B” sealant. In addition, the performance of epoxy-coated dowel bars in abating corrosion was better than that of uncoated dowels.
sealant, rigid pavement, concrete, chloride intrusion
Graduate Research Assistance, Virginia Tech, Blacksburg, VA
Associate Professor, Virginia Tech, Blacksburg, VA