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Rehabilitation of Highway MG-424

Project information

Project name

Rehabilitation of Highway MG-424

Location

Minas Gerais, BR

Principal

DER-MG

Design

Eng. Marcílio Augusto Neves Consultoria

Contractor

TORC Ltda.

Construction time

2013

Project details

Project description and challenge

MG-424 is a public highway, which begins in the metropolitan region of Belo Horizonte, the capital city in the state of Minas Gerais in Brazil. This highway carries a high volume and heavy traffic loads and is an important transportation connection in the southeast region of the country. The existing pavement consists of a Portland cement concrete pavement, which, over the years, has received an asphalt overlay to improve the surface driving conditions.

In December 2012, evaluation of the MG-424 pavement section between MG-010 in Belo Horizonte and LMG-800 in Pedro Leopoldo exhibited severe pavement deterioration and distresses. The joints and cracks of the rigid pavement had propagated through to the existing asphalt overlay, resulting in reflective cracking. The surface also presented distresses where the underlying concrete pavement suffered from joint spalling and signs of pumping and a major rehabilitation for structural strengthening was required.

Solution

With the objective to verify the structural condition of the rigid pavement and the load transfer efficiency across the joints, the Crack Activity Meter (CAM) was used. This device measures the relative vertical and horizontal displacements of the joint or crack walls by passing an 8.2-ton vehicle (or another standard axle load). Dependingon the output magnitude of the movements, it is then possible to identify if a slab is stable or if it should be stabilized, fractured or removed.

According to the obtained displacements and analysis, using the load transfer efficiency concept, the majority of the pavement sections were classified between fair and good. Based on this condition assessment, a decision was made not to completely remove or fracture the entire rigid pavement, and unstable slabs were repaired and re-seated using a heavy roller to minimize and or eliminate any observed vertical displacements.

The construction process started early in 2013 and involved milling off the existing asphalt surface, mending the concrete slabs in need of repair described above and installing a 40 mm hot mix asphalt leveling course to re-establish any irregularities in the pavement cross-section. The final phase of work included installing HUESKER’sHaTelit C 40/17 asphalt reinforcement grid over the entire leveling course and then applying a 50 mm compacted hot mix asphalt wearing course. The reinforcement again was utilized to retard and mitigate the possibility of reflective cracking through to the new surface.

Benefits

After nine years since the rehabilitation and restoration work was completed, the pavement condition was visually inspected and evaluated. The reinforced areas of highway MG-424 are performing very well and no reflective cracking were observed. The use of HUESKER’s HaTelit C 40/17 polyester asphalt reinforcement grid has been effective in delaying the propagation of cracks developing from the discontinuities of the existing underlying concrete pavement.

The economic benefit of utilizing CAM, making the necessary repairs to the existing concrete pavement, adding the reinforcement grid to the new hot mix asphalt overlay, all have shown to be an effective-economically viable alternative to traditional constructions methods that would have resulted in significantly higher rehabilitation costs. Thus, the economic and environmental benefits through savings on construction costs, time and disposal costs have been realized.