DateLaboratory Testing of Portland Cement Concrete Patch Material ...

Table 1. Rapid Setting Concrete Patch Material RequirementsWisDOT REQUIREMENTTESTED ASTM TEST 2001 WisDOT APPROVED DBR WARRANTY SPECIFICATIONPROPERTY PROCEDURE PRODUCTS LIST ITEM 416.0623.S (2004)Compressive Strength ASTM C 392000 psi @ 2 hours4000 psi @ 7 days3000 psi @ 3 hoursFreeze/Thaw Durability minimum durability factor minimum durability factor(w/ 5% sodium chloride solution) ASTM C 666 of 90% after 300 cycles of 90% after 300 cycles(using Procedure B) (using Procedure A)Initial Time of Set ASTM C 266 minimum of 15 minutes no requirementLinear Shrinkage ASTM C 531 maximum of 0.100% @ 3 days maximum of 0.100% @ 3 daysAlthough the three aforementioned patch materials met WisDOT's requirements in 2001,within one year they all showed signs of early distress on STH 13. All of the test sectionsconstructed with either Tamms Speed Crete 2028 or Mn/DOT 3U18 mix exhibitedmicrocracking and/or debonding, most likely caused by shrinkage (see Figure 1 below). Thedistresses observed in the Mn/DOT 3U18 test sections were the most severe.Figure 1. Patch Material Distress on STH 13MICROCRACKDEBONDINGDEBONDING FROM THETRANSVERSE EDGESOF THE SLOTSThe Mn/DOT 3U18 test sections exhibited both debonding and microcracking in some areas (left).Less severe debonding of the patch material, from the transverse edges of the dowel bar slots, wasobserved in the Tamms Speed Crete 2028 test sections (right).Since the Mn/DOT 3U18 patch material was significantly less expensive than the TammsSpeed Crete 2028 (approximately 1/10 th the cost) and its components were readily available,WisDOT deemed it worthwhile to seek an inexpensive way to improve the performance ofthe material. This study tested and evaluated various modified Mn/DOT 3U18 mixes in anattempt to prevent patch material shrinkage, and any associated cracking and debonding.The objective of this research was to find a cost-effective method of modifying the Mn/DOT2