Current maintenance techniques for the repair of D-cracked concrete pavements are costly and not very effective. In an effort to solve this problem two relatively new materials were used on a section of I-90 in southwestern Minnesota. Silanes were used in an attempt to retard the D-cracking process by protecting the pavement from moisture and chemical damage. The other material, High Molecular Weight (HMCW) Methacrylate monomers generally act as a "glue" to cement the fractured concrete particles back together. Both materials were placed on three separate test sections. Four silanes and three HMW methacrylates were used Each test section varied in the extent of D-cracking present.
Results to date indicate that the effectiveness of silanes in extending the service of D-cracked concrete pavements is questionable. They appeared to reduce cracking in one test section but perform similar, or worse, than the control in the other two. HMW Methacryllates appear to be effective in holding a D-cracked pavement together for approximately 18 months, However, the pavement must have cracks wide enough for the material o penetrate and form a substantial bond.
Waste tires have been a disposal problem in the past and are continuing to accumulate throughout the U.S. today. Using shredded waste tires as a lightweight fill material for road construction has proven to be a beneficial use of this waste product. Shredded tires have been used as a lightweight fill material in Minnesota, Colorado, Oregon, Washington, North Carolina, Virginia, and Wisconsin. Minnesota began using shredded tires as a lightweight fill material in 1985 on logging roads through areas with weak soils. This report documents seven sites in Minnesota that used shredded waste tires as lightweight fill. Shredded tires were proven to be a viable form of lightweight fill because they are relatively lightweight, inexpensive and non-biodegradable.
In general, the material is very elastic, very porous, contains good vibration damping properties, and is easily compacted. On the downside, shredded tires lack set design standards and specifications. The report also documents some of the environmental testing completed on shredded tires to date.
In an attempt to find new, cost effective pavement rehabilitation techniques Mn/DOT has constructed ten unbonded concrete overlays since 1977. The design and construction of each successive project built on the experiences gained from the previous project. Unbonded concrete overlays have now developed to the point where Mn/DOT feels it is appropriate to review these past experiences and develop policy on further construction of these projects. Sufficient time has also elapsed to evaluate the long term performance of specific projects and unbonded overlays in general.
