The objective of this study was to evaluate various protective coating materials which could be used to restore badly corroded plate beam guard rail to an aesthetically acceptable condition.
This study was originated in 1960 at the request of the Minnesota Local Road Research Board. Its basic objective is to determine a means of backfilling slit-type trenches so that little or no settlement results. In the first four years personnel from the Research Section, Office of Materials, Minnesota Highway Department, collected data by observing trench backfilling during regular construction operations and then measuring the subsequent settlements. In 1964, 1965, and 1966 dummy trenches were excavated and backfilled under more controlled conditions. This work was done by the City of St. Paul and Minnesota Highway Department maintenance forces. All testing was done by Research Section personnel.
In 1963, a progress report titled BACKFILLING TRENCH EXCAVATIONS was published by the Materials and Research Section, Minnesota Department of Highways. Included were general recommendations for street preparation, backfilling, and patching. Also, the effectiveness of various types of compactors was discussed and specific compaction procedures for given soils and traffic conditions were recommended. The results of the controlled backfill studies reported herein have confirmed certain of those recommendations for compaction procedures but have contradicted others. The investigation to date has not satisfied its objective and is being continued.
This study was initiated to evaluate Tri-Kote 18 Crect as a concrete treatment. Tri-Kote is a blend of chlorinated rubber, epoxies, and several other materials, which serves as a treatment for both new and old concrete surfaces. According to the manufacturer (T K Products Inc., Minneapolis, Minnesota), Tri-Kote performs as a membrane curing compound and protective treatment against salt scaling for new concrete and as a protective treatment for old concrete. The study of Tri-Kote as a protective treatment for old concrete was assumed not to be essential since the treatment now used (see MHD Specification 3917) is less expensive than Tri-Kote and is considered quite satisfactory from a performance standpoint.
The use of Tri-Kote as a membrane curing compound and protective treatment on new concrete was, however, thought to possibly be more economical than the presently used combination of a polyethylene cure and protective treatment, and was therefore subjected to an evaluation study. Since it was found that Tri-Kote, when applied at a rate somewhat greater than that suggested by the manufacturer, did meet Minnesota Highway Department Specification 3754 for concrete membrane curing compounds, only an evaluation of Tri-Kote as a protective treatment on new concrete was made. This study then consists of a comparison of Tri-Kote treated and non-treated concrete with regards to durability.
