Concrete Pavement Repair Techniques
Concrete pavements can be expected to perform optimally over their design life if properly designed and cared for through regular maintenance.
However, as pavement ages it may develop cracks due to temperature and shrinkage. These flaws can affect rideability and structural integrity.
Pavement repair should be considered when cracks exceed 10% of the total pavement surface area. These paver repairs adelaide will restore rideability and extend the pavement’s service life.
Full-Depth Patching
Full-depth patching is a permanent repair technique that involves excavating the damaged area of pavement down to its base layers before replacing it with new asphalt. This cost-effective procedure can be used to restore areas of deterioration to the surface, improve rideability and extend the life of the road.
The process begins with an inspection of the road to determine which area needs repair. A professional will then perform a concrete survey with coring, sounding techniques and FWD load-deflection studies in order to assess how much deterioration exists beneath the pavement and define repair boundaries.
Once the area has been assessed, patch material is prepared. This usually involves sandblasting or waterblasting away loose particles before applying a bonding agent that helps the patch adhere to the original slab. Once ready-mixed in a truck or other mobile batch vehicle, this patch material can then be placed into the repair area.
Depending on the type of repair required, patch material can either be injected with a spray machine or applied as a poured-in-place repair. Both methods require that concrete be placed to an exact depth equal to or greater than the design depth shown on plans.
Before applying the patch material, it must be mixed to the correct consistency. This ensures the repair has enough strength. Once applied, ensure the patch is pumped at the appropriate pressure for best results.
For this work, a fresh, dense graded hot asphalt plant mix that meets or exceeds Colorado State Highway Specifications is necessary. A minimum crew size of eight workers is necessary to do it efficiently and safely.
For this task, a hydro hammer or stinger operator and two breaking hammer operators are needed. This work usually takes place outside normal business hours and should be coordinated by the contractor so that no repair gaps remain unfilled during holidays or weekends.
Partial-Depth Patching
Partial-depth patching is a concrete pavement repair technique that restores localized surface distresses no deeper than one-third of the slab thickness. This procedure is commonly used for spalling at pavement joints and mid slab locations which have become damaged due to material issues such as D-cracking or Alkali-Silica Reactivity (ASR).
Partial depth patching is a commonly used process on concrete pavements. This cost-effective repair solution helps restore small patches of damaged pavement that has been caused by traffic.
When installing partial-depth patches, it is essential to seal them against moisture penetration from the pavement surface. To do this, use cement grout which acts as a moisture barrier between both materials. Doing this prevents delamination and cracking of the patch.
Before applying the patch material, the concrete surface must be cleaned. Doing this helps guarantee the repair material adheres properly to the pavement surface; otherwise, wheel loads and environmental stresses could separate it from its base.
Once the patch has been applied, it must be cured for optimal strength. Partial-depth repairs require extra time for curing due to concrete’s slow growth of bonding strength compared to full depth repairs; as a result, partial-depth repairs require more curing time than full depth ones.
To improve the bond between a patch material and concrete surface, it is essential to screed the repair materials from center outward. This process will create an even texture in the repair materials as well as creating a rough surface on which they can adhere better.
A bonding agent can be applied to the repair surface to promote adhesion of the new material. This agent is usually mixed on site in a small mobile drum or paddle mixer and applied evenly throughout the patch area. Furthermore, make sure to overlap it thoroughly so all areas are coated evenly.
Joint Sealant
Joint sealant is a polymer-based product used to fill cracks in concrete pavement. It can be applied as either liquid or solid, either by hand or machine. Usually, the sealant is mixed on site before application and may be self-leveling or non-sag depending on application needs. Joint sealants come in various strengths – pourable or gunnable depending on what application requires.
Selecting a sealant for an application can be challenging as different products have distinct physical and chemical characteristics. Not making an appropriate selection can lead to failure in use if taken improperly. When selecting a sealant, factors like joint design, substrates to be sealed, performance requirements and economic costs need to be taken into account.
When selecting a joint sealant, movement capability should be taken into account. This refers to how much movement a sealant can withstand in extension (+) and compression (-) relative to its original cured joint width. Coordinating this value with expected joint movement helps guarantee that your sealant performs as intended.
Sealants with the proper movement capability and design can offer long-term protection from moisture, temperature extremes, ice, oxidation, dust, and debris that could harm a structure. A quality sealant should also provide adequate adhesion to concrete pavement and its substrates while being flexible enough to withstand various weather conditions.
When selecting a sealant, the manufacturer should be able to provide data that will accurately predict its useful life in specific climate and application conditions. This insight can help avoid issues with joint durability and maintenance expenses.
One of the most commonly used tests for sealants is ASTM C719, which evaluates joint sealant performance during accelerated movement. This simulates conditions that buildings’ joints would experience over extended periods of exposure to cyclic heating, cooling, and vibration.
Another essential test procedure is ASTM C1589/C1589M. This test utilizes both continuous and periodic manual extension to compression to simulate various weathering conditions.
Resurfacing
Resurfacing is the practice of applying polymer-modified flowable mortar or cement to an existing concrete surface, offering an alternative to traditional repair techniques that involve breaking up, hauling away and pouring a new slab of concrete.
Replacing damaged concrete with this cost-effective, labor-intensive and more sanitary method is more efficient and sanitary than the more common technique of removing and re-pouring it.
The initial step in the resurfacing process is to prepare the concrete. This involves cleaning with an acid, detergent or bleach solution to remove oil and other substances. After that, a thorough 3,500 psi pressure washing is conducted to open up pours and ensure optimal bond with the resurfacing product.
Once the concrete is clean, any obstructions such as speed bumps or access ramps should be eliminated to allow resurfacing material to adhere properly. Furthermore, structures for utilities like wires or pipes may need to be adjusted.
Resurfacing pavements with medium to high levels of distress is often used. Although more expensive and less reliable than CPR methods, resurfacing is usually the most successful solution for rehabilitation pavements with moderate to severe distress.
Resurfacing concrete pavement can be done using a range of materials, including polymer-modified overlay systems and cement-based overlays. These products combine polymer resins with cement, sand and other additives to increase durability, wear resistance and aesthetic appeal.
These products can withstand freezing and thawing conditions as well as higher traffic volumes than their underlying concrete pavement. They can be installed either as a bonded or unbonded layer.
Bonded overlays are a solution that bonds thin concrete onto the top of an existing pavement, increasing its structural capacity for pavements with minimal deterioration but that cannot support future traffic demands. These products can be particularly helpful when replacing pavement that has little deterioration but is too thin to meet current demand.
They cannot be used for rehabilitation of asphalt pavements with significant deterioration due to material durability issues like “D” cracking or alkali-silica reaction.
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