What is basement wall grade carbon fiber? We have all heard of it being used for race cars, NASA and tennis rackets, but basement wall reinforcement? Why would it be used in foundation repair applications?
Carbon fiber is lightweight, noncorrosive and virtually impossible to stretch. With a tensile strength of more than 350,000 psi makes it up to 10 times stronger than steel. Accordingly, high-quality carbon fiber provides an alternative to such intrusive methods as installing steel beams with heavy equipment to brace and shore up foundation walls: no digging, jack hammering, moving utilities and duct work are required.
A foundation’s structural integrity becomes compromised when hydrostatic and lateral earth pressures exceed the strength of a concrete or masonry wall. As lateral pressures press upon the foundation, basement or crawlspace walls bow inward. Its effectiveness in counteracting such tendencies is based on standard engineering principles following Hooke’s law and a linear stress/strain relationship. For every action there is a reaction, the action is the soil pressing on the basement wall and the reaction is the carbon fiber applying a resistant force, making the wall stronger to help eliminate shifting, cracking and bowing.
One of the other big benefits of carbon fiber is its ease of use and aesthetics. You will not have I-beams lined across the basement wall. The thin layer of carbon fiber material can be painted over without creating an eyesore. Duct work and plumbing penetrations can be left alone due to its flexible nature.
Bowing Wall Repair Using Carbon Fiber
In most residential situations where bowing basement walls occur, there are several sets of forces which interact to cause the problem. The largest mobilizing force is the addition of lateral earth pressure (soil forces) in conjunction with hydrostatic pressure (water forces). These forces put a horizontal load on the wall which in turn creates a large amount of bending stresses on the masonry or concrete. The bending stress creates an unbalanced condition within the wall due to the very low tensile capacity of concrete and masonry, causing horizontal cracking in the structure. The weight of the structure above the wall helps generate a stabilizing compressive force on the wall until the lateral deflections become too large. As the wall deflects beyond the “center of mass” of the above structure, a phenomenon known as the “beam-column effect” creates additional bending stresses on the damaged wall, speeding up deterioration. Carbon Fiber Reinforced Polymers (CFRP’s) provide the required additional tensile force needed to fully develop the compressive strength and create a “balanced” situation within the wall to prevent further bowing and cracking.
Wall Crack Repair Using Carbon Fiber
Carbon fiber fabric is placed over basement wall cracks to provide strength to the cracked area. No drilling is necessary as with other crack repair systems. The advantages of using carbon fiber fabric to repair wall cracks are:
- Flexible wrap conforms to any shape
- Minimal change to structure’s shape
- Repair time is minimal – minimizing cost
- Minimal disruption and noise
- Heavy equipment is eliminated