A good portion of those rails were poured by Norwalk Ready Mix. The mix itself is a 3 aggregate mix with a very low slump. Combine that with the high temperatures of an Iowa summer and you have a pretty good recipe for low air results. The Iowa D.O.T. is in charge of monitoring these jobs at the point of production as well as onsite. The air results we were getting at the plant were dropping dramatically by the time they reached the site. The problem was that the air entrainment agent we were using at the time just couldn’t hold up to the grueling conditions of the job.
We cut the initial dosage rate of the mix and sent out our quality control representative to the job site. Once the truck arrived at the job, our quality control representative put the rest of the air entrainment in the load. With this method we were able to elevate the air content to a level that was well within the D.O.T. specifications. We now have a new synthetic air available to us called Polychem SA that can achieve the same excellent results, but with only a third of the dosage rate.