Comparison of Setting Time Measured Using Ultrasonic Wave Propagation with Saw-Cutting Times on Pavements – A Case Study

Abstract

At present, there is little solid guidance available to assist contractors in choosing when to schedule saw cutting of joints in slabs on grade. Knowledge of when the sawing window opens and closes would help in reducing the risk of raveling or random cracking due to sawing too early or too late. The aim of this case study was to confirm that initial set can be measured using an ultrasonic pulse velocity (UPV) approach in the field, and to assess whether there was a relationship between initial set and sawing time for pavement concrete in the field. This case study summarizes 24 construction sites that were visited in Minnesota, Missouri, and Iowa over a two-year period. At each site, initial set was determined using a p-wave propagation technique with a commercial device using samples of concrete collected in front of the paver and tested next to the pavement. Calorimetric data were collected using a commercial semi-adiabatic device on the majority of the sites.