MnDOT is currently implementing in-place recycling techniques as a maintenance and rehabilitation strategy for bituminous pavement structures. The techniques being employed include: Full Depth Reclamation (FDR), Bituminous Stabilized Full Depth Reclamation (SFDR), and Cold In-Place (Partial Depth) Recycling (CIR). In-place recycling of bituminous pavements has been used in Minnesota for more than ten years at the local level, longer in other parts of the country and the world. MnDOT has constructed 10 state projects since 2010 using a variety of processes and stabilizing additives.
Full Depth Reclamation (FDR) is the process of pulverizing a roadway’s flexible pavement section and a portion of its underlying base, and crushing and blending the recovered material to create a uniform base material.
Experimental concrete pavement containing variations in joint spacing, reinforcement, dowel sections, and joint fillers were used on Minnesota T.H. 36 to determine optimum design. Surface rating, South Dakota Profile Surface Rating (PSR), and Concrete Pavement Evaluation System (COPES) studies were performed to evaluate the pavements. The best sections were the 15 foot and 20 foot sections with bituminous coated or rust inhibitor painted dowels. The longer sections, 33 foot and 65 foot, and the panels with sleeved dowels performed poorly. All joint fillers failed within three years.
This report reviews pavement performance testing results on an experimental concrete pavement built on Minnesota T.H. 36 in 1958 that contains variations in joint spacing, reinforcement, dowels, and transverse joint fillers. South Dakota Profile Serviceability Rating (PSR), Minnesota Structural Rating (SR), and Concrete Pavement Evaluation System (COPES) surveys conducted in 1990 revealed that the best performing sections were the 15 foot (4.6 m) and the 20 foot (6.1 m) sections with bituminous coated or rust inhibitor painted dowels. The longer sections, 33 foot (10 m) and 65 foot (20 m), and the panels with sleeved dowels performed poorly. All transverse joint fillers, which included “Presstite 77” and rubber asphalt Minnesota Spec. 3723, failed within three years.
Researchers previously studied the sections from 1959-1969, and this report references several memos and letters on the pavement’s performance. The four basic pavement sections include: 15 foot (4.6 m) and 20 foot (6.1 m) unreinforced sections with one undoweled and three different dowel segments, and the 33 foot (10 m) and 65 foot (20 m) reinforced sections with three types of mesh and three different doweled segments.
A committee consisting of Minnesota Department of Transportation (Mn/DOT) Bridge, Pavement, and Geotechnical personnel was formed to examine the present and propose a future comprehensive Non-Destructive Testing (NDT) Program. The overall intent of their study was to define the scope of Mn/DOT's NDT program focusing on the Offices of Construction and Materials Engineering, Minnesota Road Research, and Bridge, with the intent of providing basis for future investment and use of NDT methods.
Several NDT devices are currently being used by the Department. They have a great potential for saving the Department time and money, and will enable the employees to perform their jobs better and more efficiently. Other NDT devices are still being investigated for their potential benefits to the Department, and have not been fully evaluated.
Though these devices may ultimately save time and money and improve performance, many are labor intensive. Staff approval must be obtained before making large financial or personnel commitments. It is recommended that each of the three areas have someone in charge of the evaluation of all new equipment and methods.
This Soil Factor Design Method was written for counties, townships, and municipalities for use in designing aggregate roads. Although many design methods for aggregate roads exist, most require thorough soil identification and soil strength testing. Since most local agencies do not have the means to perform elaborate testing of soils and because they are familiar with soil factors, this design method should be helpful. This procedure requires soil identification, traffic counts and rational judgement.
At present Mn/DOT does not have a design method for aggregate roads. It is not the intention of this manual to change the present legal load limits for gravel roads.
For those who would like a more thorough design method, or more background information on aggregate roads, the method includes information on the use of the U.S. Forest Service Aggregate Surface Design Guide.
Also included is information regarding compaction, drainage, frost action, geosynthetic use, lime stabilization, and an appendix with sample problems based on the Soil Factor and Forest Service design methods.
