Concrete Removal & Replacement
Concrete provides excellent performance throughout the service life of the structure when it is mixed properly and caution is taken during the curing process (we recommend a curing process of at least 4-7 days). However, once the mix has been laid and dries, the aging process begins. Without ongoing maintenance, water may enter through cracks and holes may form, undermining the substrate. In this case, the most effective form of repair is to remove and replace the deteriorated area.

Procedure
This process consists of several important steps to ensure that the repair is performed properly.

Concrete Installation
For concrete installation, we use a paste consisting of Portland cement, pure water and aggregates.

Portland Cement
Vastly superior to all natural cements, Portland cement consist of five major compounds:

• Type I: General purpose cement.
• Type II: Used in general construction – a good choice for installations in warm weather climates.
• Type III: Used when high strength is desired at very early periods.
• Type IV: Low heat Portland cement. Used in massive structures such as dams.
• Type V: Is used in areas where soils or nearby waters have a high alkali content.

Water
Water causes the hardening of concrete through a process call hydration. To prevent side reactions from occurring, which may weaken the concrete or otherwise interfere with the hydration process, the water must be pure. Another key factor in the production of concrete is the water/cement ratio. Strong cement has a low water/cement ratio. However, cement required water to be workable for placing, which reduces the strength. Finding a perfect balance so that it is both strong and workable is critical when making concrete.

Aggregates
Aggregates are inexpensive, chemically inert fillers that come in various shapes, sizes and materials ranging from fine particles of sand to large, coarse rocks such as gravel and stones. Concrete is composed of 70-80% of aggregate material. Since aggregates make up such a large volume of concrete, their selection is important. They should consist of particles with adequate strength and resistance to exposure conditions and should not contain materials that will cause deterioration of the concrete.

Concrete Reinforcement
Settling of poorly compacted fill and/or freezing and thawing of the sub-grade are common causes for concrete slab instability. To repair this defect, wire mesh reinforcements are used to increase tensile strength (resistance to forces that bend and pull a material). The wire mesh stabilizes concrete by preventing cracks or joints from opening up or shifting vertically.

Water loss and shrinkage can also cause cracking in concrete. To remedy this, polypropylene fibers are added to the concrete mix. These fibers effectively block cracks.

Concrete Bumper Block
To provide better traffic flow, many parking lots have bumper blocks installed. Often, these blocks become damaged, crumble and cause hazards on the lot.

Commercial Asphalt Maintenance provides full-service concrete bumper block repair. Damaged blocks are hauled away to authorized dump sites and new blocks are installed and properly pinned into place.