7 Maintenance and Rehabilitation Strategies for Concrete Pavements

Concrete roads are known to be a durable option for road construction due to their excellent stress force distribution. This is due to concrete's stiffness, which distributes weight evenly across a wider surface area, in contrast to the concentrated points of loading on flexible pavement.

To prolong the performance of concrete pavements, we recommend the following maintenance and rehabilitation strategies:

1. Joint and crack sealing

   Cracks and joints are sealed to prevent water and noncompressible materials from entering and causing potential damage. Different types of sealants are used for this purpose:

   Hot-pour liquid sealants are heated and melted down to a liquid before being poured into cracks and joints. Following their application, the road can be opened to traffic once the sealants have cooled and gained enough rigidity. Hot-pour liquid sealants have a service life of 3-5 years.

   Silicone sealants are silicone polymer compounds poured into joints in outdoor temperatures. They are typically ready for traffic loads within 30-60min of application, and have a service life of 8-12 years.

   Compression seals utilise rubber compounds, typically neoprene materials, that are compressed into a joint by pushing against the joint walls. These seals have a service life of over 15 years and can be used for traffic immediately after application.

2. Slab stabilisation

   Slab stabilisation aims to fill voids that form beneath the slab due to pumping, erosion, or consolidation of the base. Neglecting these voids can lead to their enlargement, which can result in faults, corner breaks, or cracking. The recommended method for filling these voids is through the injection of grout (cement and fly ash slurry) via predrilled holes in the slab.

3. Diamond grinding

   Diamond grinding is a process that restores pavement surface friction or smoothness. It uses diamond saw blades mounted on a gang to grind off a thin layer of the surface. It can fix roughness caused by faulting, studded tire wear, or slab curling.

4. Patches

   Patches in rigid pavements are used to treat localised slab problems such as spalling, popouts, scaling, joint deterioration, corner breaks, and punchouts. Partial-depth patches are used for moderate spalling and localised areas of severe scaling that do not exceed 7.6 cm depth and 1.1 m² in area. Full-depth patches are used for repairing severe spalling, punchouts, corner breaks, severe slab cracking, and localised areas of severe scaling that go beyond the upper one-third of slab depth or originate from the slab bottom. HMA is used for emergency patches, while Portland cement or high early strength gain cement should be used for permanent patches.

5. Load transfer devices

   Load transfer devices rehabilitation involves cutting a perpendicular slot between two adjoining slabs, inserting a dowel, and refilling the slot with a fast-setting polymer concrete. This method can extend the service life of rigid pavements by 10-20 years when combined with other restoration techniques, depending on pavement condition, traffic loading, and environmental factors.

6. Precast panels for repair and rehabilitation

   Precast concrete pavements are being evaluated for repairing localized failures and rehabilitating poorly performing pavements. They offer benefits such as improved control over concrete processes, enhanced performance and durability from post-tensioning, cost savings through reduced pavement thickness, and shorter construction time with minimal lane closures.

   The use of precast concrete pavements is being evaluated for repairing localized failures in concrete pavements (e.g., full-depth repairs) and rehabilitating long stretches of poorly performing asphalt and concrete pavements. Advantages of precast concrete pavements include improved control over concrete batching, forming, and curing, increased performance and durability from post-tensioning, reduced pavement thickness resulting in savings, and reduced construction time with fewer lane closures.

7. Portland cement concrete overlays

   PCC Overlays are increasingly being used as rehabilitation techniques for both existing PCC and hot mix asphalt pavements. They have the potential to extend service life, increase structural capacity, reduce maintenance requirements, and lower life cycle costs. Advancements in PCC paving technology, such as the use of zero-clearance pavers, fast-track paving concepts, and high early strength PCC mixtures, have significantly improved the ability of PCC overlays to serve as a viable rehabilitation alternative.

   Whitetopping is a Portland cement concrete overlay on existing asphalt concrete pavement used as a road surface course where other paving materials and methods have failed due to rutting or general deterioration. There are three types of whitetopping: conventional (thickness greater than 20 cm), thin (thicknesses over 10 but less than 20 cm), and ultrathin (5-10 cm). Ultrathin whitetopping (UTW) is a bonded, fiber-reinforced concrete overlay designed for low-speed traffic areas or areas with a lot of stop-and-go traffic, such as street intersections, bus stops, or toll booths. Joint spacing is critical to a good performing UTW. Short joint spacing is common in both directions of the slab, creating a mini-block paver system. Limited experience with UTW indicates that joint spacing should be no more than 30-45 cm each way per centimetre of whitetopping thickness. For example, a 7.5 cm UTW surface should be joined into 90 x 90 cm or 120 x 120 cm squared, with joints sawed early to control surface cracking.

In conclusion, maintenance and rehabilitation of concrete pavements are crucial to ensure their longevity, structural integrity, and safe use for transportation. With the advancement in technology and innovative techniques, various options such as precast panels, Portland cement concrete overlays, and whitetopping are available for repairing and rehabilitating concrete pavements. These options offer benefits such as increased durability, reduced construction time, lower maintenance requirements, and lower life cycle costs. Proper maintenance and rehabilitation of concrete pavements can not only extend their service life but also provide a cost-effective solution to the challenges faced in transportation infrastructure.

Figure 1: Types of maintenance and rehabilitation strategies for concrete pavements.