CONCRETE CRACK REPAIR
From Bridges and parking garages to foundations and retaining walls, Carbon Fiber Reinforced Polymer (CFRP), has been relied upon for the strengthening of concrete infrastructure under the most extreme conditions.
The SRS-660BI has a design tensile capacity of 35,496 lbs per 12”. This strength however is limited by the bond strength of the composite to the concrete substrate. If a 400 psi concrete bond strength is assumed then the strength developed by the epoxy bond on either side of the crack is as follows: 6” x 12” x 400 psi = 28,800 lbs. The ability to add this kind of strength to a crack repair has significant benefits.
SRS-660BI can be used to remedy a problem injection or to simply reinforce a crack repair to provide peace of mind that it will not re-open.
Vertical Wall Cracks
These are often present in poured walls, may appear wider at the bottom and continue to increase in width and length. These vertical foundation cracks often occur shortly after construction and can extend down the entire length of the wall to the floor.
As these cracks worsen they can possibly be the site of water infiltration.
Vertical foundation wall cracks can structurally reinforced by confining the area with SRS-660 Bidirectional Carbon Fiber. This advanced composite creates a permantent bond over the crack by sealing the carbon fiber to the concrete with a structural epoxy adhesive.
Shrinkage typically occurs as concrete cures, this chemical reaction is affected by the amount of water, aggregate type, humidity, type of concrete, groundwater, sun exposure, temperatures and other variable conditions. These cracks often originate at the time of construction and as concrete shrinkage occurs, it will develop internal stresses. Cracking relieves this stress during curing
Poured concrete foundation walls - Shrinkage cracks can be caused by poor mix, rapid curing, improper or omitted steel reinforcement. Temperature swings consistent with the change of season can also cause the concrete to expand or contract to cause cracking
Block foundation walls - Shrinkage cracks are generally uniform in width, form at the center of the wall and are also caused by curing and temperature variations.
Repairs Of Wall Shrinkage Cracks
It is important to prevent water intrusion by chipping out the crack, filling with masonry patching compound, epoxy, polyurethane foam or other sealants then structurally reinforcing the cracked area with bidirectional carbon fiber. This additional reinforcement provides an additional layer of waterproofing as well as arrest any further movement of the crack.
Causes Of Wall Settling Cracks
Settlement cracks are often caused from improperly placed or omitted steel reinforcement or movement in the foundation due to poorly prepared foundation footings. Hydrostatic pressure from sub-grade settlement can also contribute to settlement as well as horizontal loading from the structure above and backfilling can also cause uneven stresses and lead to structural cracking. Hydrostatic pressure exerts force against the exterior foundation wall and becomes more severe further underground.
Other contributing factors can be caused from damage by use of heavy equipment near the wall, premature or excessive backfilling before the floor framing was set, or earth loading worsened by water or frost.
Block walls will crack straight along a joint or stepped near the ends of the wall. This, too, can be extremely dangerous and risk collapse if wall courses are broken. In all cases, cracks will appear in multiples in various locations around the foundation.