This study was undertaken to determine the accuracy and reliability of portable, automatic, vehicle classification devices. Available classification equipment was identified, borrowed, and field tested against manual traffic classification to meet the objectives of the study. Field tests were conducted at both high-speed, high-volume and low-speed, low-volume sites.
It was found that portable, automatic vehicle classifiers are generally more accurate at low-speed sites and that when classification errors are made, the errors are in multiple-axle categories. Detection appears to be the biggest problem both in getting an impulse to the devices from the pneumatic road tubes and in securing the tubes in place in high-volume traffic areas.
The Minnesota Department of Transportation (Mn/DOT) investigated a polymer concrete (PC) patching material in cooperation with the Brookhaven National Laboratories (BNL) and the Federal Highway Administration (FHWA). This material has been previously tested by other states throughout the country. The material is claimed to be a rapid curing, durable material for patching potholes and deteriorated cracks in Portland cement concrete pavements and bridge decks.
Previous field tests of PC materials have been small in scope and size. The problems associated with the material were the tendency of the monomer to drain from the system, the development of shrinkage cracks in the polymerized material, and the need for a knowledge of chemistry to mix the monomer system. The BNL material is supposed to correct these drawbacks.
Mn/DOT made a laboratory study of the PC material by producing a control mix of portland cement, low-slump concrete to evaluate how PC material compares to the low-slump concrete with respect to:
- freeze thaw durability,
- compressive strength,
- tensile splitting strength; and
- chloride permeability.
Shear bond strength tests of the PC material are being conducted by the BNL. Field evaluation of the PC material has proven to be inconclusive. Patches failed in both the concrete pavement and the bridge deck. The bridge deck patches had to be removed completely. These failures are not due to the PC material itself.
ln 1970, a research project was constructed on I-94 near Rothsay, Minnesota with the objective of determining the feasibility of constructing a portland cement pavement over bituminous or cement treated bases and determining the structural requirements. The project was constructed with an 8-inch and 9-inch thick pavement over a section of bituminous-treated, cement-treated, and conventional gravel base. Each thickness of pavement had doweled and undoweled portions.
This study was initiated to further investigate the cathodic protection continuously reinforced concrete pavements (CRCP). An initial cathodic protection system has been in operation for seven years on two lanes of interstate highway. It was felt that economies could be achieved by building a system that would protect both roadways of a 4-lane, interstate highway. This report is the first product of that study. This report discusses the CRCP pavement problem in Minnesota and describes the design and construction of the cathodic protection system. Future reports will document the performance of the system.
A typical concrete pavement has expansion and contraction joints across and along the pavement surface. The joints allow the pavement to change in dimension with changes in temperature. A continuously reinforced concrete pavement (CRCP) does not have expansion or contraction joints. Random, closely spaced cracks are expected to develop naturally and allow for expansion and contraction due to temperature changes. The many random cracks eliminate expensive joint maintenance. This maintenance-free service life feature has not occurred in Minnesota.
During past years, an increasing number of CRCP s have exhibited deterioration where pieces of concrete separate from the surface of the pavement and potholes result. This is termed spalling. The frequency and extent of this deterioration has progressed from isolated and random to widespread and frequent. A comprehensive program was initiated by Mn/DOT to study this problem and develop possible solutions.
This CRCP inventory is a physical evaluation of the extent of corrosion on random, sections of pavement. It is related to concurrent efforts which will evaluate CRCP rehabilitation, techniques.
This document discusses a series of pavement rehabilitation seminars and workshops that were held in March, 1983. These workshops were organized by MnDOT as a way for staff from different districts to collaborate on pavement rehabilitation techniques.
High quality aggregates for highway construction are in short supply in many parts of Minnesota. Although the current total supply is adequate, the distribution of sources results in localized shortages. In some areas, it is necessary to import high-quality aggregates from distant locations. Long haul distances can increase aggregate prices substantially, add significantly to the overall project cost, and require the expenditure of sizable amounts of energy. One available source of high-quality aggregate is existing portland cement concrete pavement currently in need of reconstruction. Re-using this aggregate would conserve natural resources, result in cost savings in areas experiencing aggregate shortages and conserve natural resources, result in cost savings in areas experiencing aggregate shortages, and conserve energy in the form off fuel savings when aggregates must be acquired from distant sources. A research study was undertaken to; Determine the feasibility of recycling portland cement concrete pavement; evaluate the new recycled pavement; determine the cost effectiveness of recycling versus conventional paving; and determine the amount of energy consumed and natural resources conserved. Economic and engineering factors led to the selection of a 16-mil (25.7 km.) segment of U.S. 59 from Worthington to Fulda in Southwestern Minnesota for :his study. The in place roadway which was constructed in 1955 and consisted of a 9-7-9 inch (23-18-23 cm.) thick, 24 foot (7.3 m) wide, non-reinforced "D"-cracked concrete pavement with soil shoulders was broken, salvaged, and crushed. Material passing the #4 sieve (0.187 in., 0.476 cm) was used for base stabilization and shoulder aggregate, and material retained on the #4 sieve but passing the 3/4 in. (1.905 cm) sieve was used] as the coarse aggregate for concrete paving. Pavement removal began May 15, 1980 and concrete paving was completed September 24. 1980.
