Concrete pavement that has been properly designed and constructed can last for decades. To guarantee it reaches its full service life–with optimal rideability throughout each year of its existence–agencies should develop a preventative maintenance plan.
Regularly performing small repairs at regular intervals will save time, money, and effort in the long run. By accurately recognizing what types of issues will be revealed during these inspections, agencies can create efficient repair protocols.
Full-Depth Repair
Full-depth repair is a common pavement renewal preservation strategy used by state agencies, municipalities and other owners to address defects at joints and cracks. This method restores deteriorated areas of concrete, improves rideability, deters further degradation and minimizes foreign object damage potential.
Effective full-depth repairs require proper planning and construction techniques. These include conducting a comprehensive field survey, coring/sounding methods, as well as FWD load deflection studies.
These data can be used to accurately assess the extent of pavement deterioration beneath the surface and pinpoint repairs that are necessary. Furthermore, this process helps determine if additional maintenance or reconstruction work is required.
When a full-depth repair is necessary, experienced personnel conduct an exhaustive field survey using coring and sounding techniques to accurately identify the extent of deterioration. Once identified, a full-depth saw cut is made at the repair boundaries for accurate placement of materials.
After the full-depth saw cut is made, longitudinal tie bars are drilled and installed to maintain continuity with the existing concrete. Finally, the excavation is filled with fresh concrete.
Full-depth repair may be required for low to high severity blowups and corner breaks, medium to high severity D-cracking, punch-outs, localized distresses, construction joint distresses, joint deterioration, spalling, reactive aggregate cracking and deterioration adjacent to existing repairs.
Distresses such as these often lead to significant pavement deterioration and have an adverse effect on rideability, safety and structural integrity. Therefore, they must be remedied in order to extend the service life of concrete pavement.
This type of repair necessitates an experienced crew, the right equipment and efficient construction techniques. It’s time-consuming so careful planning is key to avoid premature failure or other issues. Nonetheless, this repair method has proven popular for many concrete pavements due to its reliability and effectiveness.
Partial-Depth Repair
Partial-depth repair is a concrete pavement repair technique used to address localized areas of pavement distress. It restores ride ability, prevents further deterioration, minimizes foreign object damage potential and provides proper edges so joints can be successfully resealed.
Repairs involve excavating an area of deteriorated concrete that only extends up to one-third of a slab thickness and replacing it with appropriate repair materials. Depending on the type of repair material and where the repair is being made, a new joint sealant system may need to be applied as well.
Portland cement concrete mixtures are commonly used to repair partial-depth damage, but specialized materials and mixes are also available. These include special gypsum-based cement mixes, admixtures that accelerate curing time, as well as commercially available epoxy or polymer concrete mixes.
These materials are mixed on-site and heated to the appropriate temperature for applying patch material. They boast a high strength-to-weight ratio, similar to existing concrete in properties such as modulus of elasticity, expansion coefficients, and bonding strengths.
Some States have prescribed hot pour, polymer-modified resin-based repair materials for partial-depth repairs. These cheaper and easier-to-work with materials don’t have the same surface texture requirements that standard Class A patch material requires. Furthermore, diamond grinding and cold milling may cause the hot pour material to melt, pull out of place, or gum up equipment grinding/milling heads.
Resealing the repair requires sawing and sandblasting the joint faces to create the proper shape factor, then sealing with quality sealant. This step is essential in protecting concrete from moisture and incompressibles that could otherwise cause further deterioration or failure of the joint.
In addition to resealing, a compressible insert may be placed along the working joint or crack in order to keep the patch material from penetrating adjacent concrete. Common compressible insert materials include Styrofoam or asphalt-impregnated fiberboard.
After the partial-depth repair is complete, an overlay of asphalt or asphalt-impregnated fiberboard may be applied to the repaired area. This helps protect the patch material from shrinking under heavy traffic and further damaging the joint.
Joint Repairs
Joint repairs are sometimes necessary when full-depth pavement replacement is either not an option or more cost effective than repairing existing concrete. Common conditions requiring joint repairs include surface scaling and spalling, cracks at edges or joints, as well as other deterioration not extending below the mesh of adelaide paving surface.
Repairs are commonly classified as full-depth or thin-bonded, depending on the extent of damage. A full-depth repair necessitates removal and replacement of the entire slab, while a thin-bonded patch requires only the removal of the damaged section of pavement.
Patches should not be smaller than the width of a lane and must not impede traffic operations. When the patch measures more than 4.5 metres (15 feet), tie bars or wiggle bolts must be used as support, with this system being secured onto the concrete surface using anchoring grout.
Before placing new concrete, the repair area must be prepared. This involves clearing away any dirt or dust from the existing pavement, cleaning reservoir faces with water, and then sandblasting away any slurry residue left on surfaces. Sandblasting also creates a texture for sealant adhesion which reduces joint spalling risks.
Be careful when sawing or tearing away at the base underneath the pavement during repair operations. If a backhoe bucket plate is used to excavate this foundation, exercise extreme caution.
Furthermore, all perimeter saw cuts should be performed with diamond saws to avoid pinching or locking of the blade during expansion of concrete during hot weather conditions.
Once the area is ready to be repaired, a bond breaking board or similar material should be applied along the longitudinal face of the repair in order to prevent movement of the old concrete. This step is essential in making the repair durable.
Once the bond breaker has been applied, a straightedge test should be performed before the new concrete hardens to guarantee that the transition on and off the repair meets an accuracy tolerance of 1/8 inch in 10 feet (3mm in 3.0 meters). This step is essential to guaranteeing the longevity of your pavement repairs.
Patching
Patching is a type of pavement repair in which an area with damaged pavement is patched with concrete material. It’s commonly used to patch potholes, cracks and other minor distresses.
Patching pavement involves first removing damaged concrete and loose materials from the repair area. This usually requires a saw cut and liftout operation to isolate the damaged section from the rest of the pavement. Once this section has been taken out, new subbase material can be added and compacted for preparation of the repair area.
Patch material consists of one part high early strength portland cement, one and a half parts fine aggregate, and one and a half parts coarse aggregate by volume. The amount of air added should be enough to achieve an air content of 8 +- 2 percent. Add enough water for placement but do not let the concrete exceed 4 inches (100 mm) in slump.
Apply the patching material to the area using a trowel or similar tool. Stab it into the compound to eliminate air pockets and help work it into cracks.
Once the crack has been filled, create a smooth surface with the patch. Finish it longitudinally with either a vibratory screed or 3-m (10 ft) straightedge to match the texture of the surrounding pavement.
Sealant reservoirs should be created or sawed at the patch boundaries to prevent spalling at the joints. Joint sealants such as hot-poured asphalt-rubber sealants are typically specified for transverse joints, while low modulus silicone sealants are popular choices for longitudinal repairs.
Once the patch has been prepared, it must then be adhered to existing concrete with bonding grout. The mixture is poured into the patch and slightly overfilled, then vibrated and struck off to form a strong bond with the concrete.
Before the concrete cures, inspect the repair for trueness. Draw a 10-foot (3 m) straightedge across it parallel to the centerline with both ends resting on existing pavement. If there are discrepancies, make necessary corrections until it matches up perfectly with adjacent slab edges.
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