All concrete shrinks as it dries. As it shrinks, internal tension builds up, and if that tension gets too strong, the concrete can crack. These cracks are called drying shrinkage cracks.

Control joints are placed into the concrete to manage this natural cracking. They create planned weak spots in the concrete so cracks form in those locations instead of spreading randomly across the surface.

The occurrence of random cracking at control joints can be greatly minimized by following guidelines established by the American Concrete Institute (ACI) for concrete slab installation which includes:
• Proper subgrade preparation
• Concrete mixture selection
• Proper installation practices including control joint installation and proper curing of the concrete after final finish.

Reinforcement in exterior pavements and interior slabs helps keep control joints, saw cuts, and small cracks tight, so both sides move together when vehicles drive over them. It also helps reduce how wide joints and cracks open and close as the concrete expands and contracts with temperature and humidity changes.

Reinforcement such as rebar, welded-wire mesh, or fibers doesn’t prevent concrete from cracking. Instead, it works after cracks form. When control joints are placed correctly, cracks are encouraged to form at those joints rather than randomly.

To effectively control cracking from drying shrinkage and temperaturechanges, rebar and welded-wire mesh must be positioned in the upper portion of the pavement or slab. This placement allows the reinforcement to hold the concrete together, keeping cracks and joints tight as the slab expands, contracts, and carries loads.

No. The primary purpose of reinforcement is to help keep control joints and cracks tight, if they occur, due to drying shrinkage or temperature changes. It’s important to note that reinforcement does not prevent cracking, it simply helps manage it.

RESOLVE synthetic concrete reinforcing fibers are mixed into your readymixed concrete. Each fiber meets certain performance criteria from reducing plastic shrinkage cracking, and providing temperature and shrinkage reinforcement to improving impact abrasion resistance.

The American Concrete Institute (ACI) recognizes the use of macro synthetic fibers as a suitable replacement for reinforcing bars and welded wire mesh when used to control drying shrinkage cracking and thermal changes (ACI 544.4R).

1. Micro fibers, combined with proper curing practices after finishing, help minimize the risk of plastic shrinkage cracking. This type of cracking occurs when the surface of the concrete dries too quickly during finishing operations.

2. Macro fibers can serve as an alternative to traditional reinforcement such as rebar and welded wire mesh. They are effective in controlling
cracks caused by drying shrinkage and temperature fluctuations, particularly in exterior pavements and interior slabs on grade.

Unlike rebar or welded-wire mesh, macro synthetic fibers reinforce the concrete in all directions. When a crack forms, ideally at a control joint, many fibers cross the crack and help keep it from opening too wide or spreading. Additionally, macro synthetic fibers enhance the concrete’s toughness, improving resistance to impact, abrasion, and fatigue-related deterioration.

The appearance of fibers on the surface is greatly minimized with proper concrete mixture selection and installation practices.