Foundation Repair - Securing Foundations with CarbonArmor Systems

1. Introduction:

A homeowner in Sugarloaf, Pennsylvania, reported a horizontal crack in their concrete block basement foundation wall. Such cracking in concrete block foundations can indicate significant lateral pressure, potentially leading to bowing, shearing, and eventual structural failure if left untreated. Recognizing the severity of the issue, Liberty Basement Systems was contacted to provide a durable and effective solution.

2. Problem Identification and Assessment:

A thorough inspection by a System Design Specialist confirmed the horizontal crack as a critical indicator of foundation compromise. Horizontal cracking in block walls is often attributed to excessive lateral earth pressure against the foundation, hydrostatic pressure from groundwater, or a combination of both. Without intervention, this condition can worsen, leading to increased structural instability and potential water infiltration.

3. Solution: Carbon Fiber Reinforcement System:

To address the compromised foundation wall, the CarbonArmor® system was specified. This system utilizes unidirectional carbon fiber-reinforced polymer straps bonded to the interior surface of the foundation wall using a high-strength epoxy resin. Carbon fiber offers exceptional tensile strength-to-weight ratio, making it an ideal material for reinforcing concrete structures. The key components of the system include:

• Carbon Fiber Straps: High-modulus carbon fiber rovings woven into a unidirectional fabric, providing significant tensile strength along the direction of the fibers.
• High-Strength Epoxy Resin: A two-part structural epoxy adhesive designed to create a strong, durable bond between the carbon fiber straps and the concrete block substrate. The epoxy also penetrates the concrete pores, enhancing adhesion and load transfer.
• ArmorLock Brackets: Steel brackets mechanically fastened to the top of the foundation wall and anchored to the floor joist system. These brackets provide additional resistance against inward movement and top wall deflection.

4. Installation Methodology:

The installation process involved the following key steps:

1. Surface Preparation: The concrete block wall surface was prepared by removing any loose debris, efflorescence, or coatings to ensure proper adhesion of the epoxy resin.
2. Strap Application: Pre-cut CarbonArmor® straps were positioned horizontally across the cracked section of the wall, aligned to counteract the primary tensile stresses induced by the lateral pressure.
3. Epoxy Saturation: The epoxy resin was thoroughly mixed and applied to saturate the carbon fiber straps, ensuring complete impregnation and bonding to the concrete substrate.
4. ArmorLock Bracket Installation: ArmorLock brackets were strategically placed along the top of the wall and securely fastened to both the concrete block and the floor joist system, providing a mechanical anchor against inward movement.
5. Curing: The epoxy resin was allowed to cure for the manufacturer-specified time to achieve its full bond strength.

5. Discussion:

The application of the CarbonArmor® system provides a non-invasive yet highly effective method for stabilizing cracked concrete block foundation walls. The high tensile strength of the carbon fiber straps resists the lateral forces acting on the wall, preventing further crack propagation and inward movement. The epoxy resin ensures a strong and durable bond, effectively transferring the load from the wall to the reinforcing straps. The addition of ArmorLock brackets provides crucial support at the top of the wall, mitigating the risk of bowing or leaning.

This approach offers several advantages over traditional repair methods, such as underpinning or wall replacement, including:

• Minimal Disruption: The installation process is relatively quick and does not require extensive excavation or disruption to the surrounding landscape or interior of the home.
• High Strength and Durability: Carbon fiber is significantly stronger than steel and is resistant to corrosion, ensuring a long-lasting repair.
• Concealed Application: The thin profile of the carbon fiber straps allows for concealment with standard wall finishes.

6. Conclusion:

The successful implementation of the CarbonArmor® system in the Sugarloaf residence demonstrates its efficacy in stabilizing horizontally cracked concrete block foundation walls. This non-invasive technique provides a robust and durable solution, effectively mitigating the risk of further structural damage and providing the homeowner with renewed confidence in the safety and stability of their home. The integration of carbon fiber reinforcement with mechanical anchoring offers a comprehensive approach to addressing the underlying causes of foundation wall failure due to lateral pressure.