Understanding Concrete Stem Wall Repairing Arizona: Fact vs. Fiction

As a homeowner, one may encounter various claims and solutions offered by "Foundation/Concrete Repair Experts" regarding concrete stem wall repair. However, it's crucial to have a clear understanding of the facts to make informed decisions about the best course of action for addressing stem wall issues. In this article, we'll delve into the science behind stem wall deterioration and expose certain misconceptions.

 

The Root of the Problem: Rusting Rebar and Concrete Cracking

 

One common issue that homeowners face with concrete stem walls is cracking caused by rusting rebar. Rebar is a steel reinforcement placed in concrete structures to enhance its tensile strength – its ability to resist being pulled apart. Over time, rebar can rust, forming iron oxide (rust), which takes up significantly more space than the original rebar. This expansion exerts pressure on the surrounding concrete, leading to cracking and even the chunking off of concrete around the rusting rebar.

 

  

 

Exposing the "10,000 psi Repair Mortar" Claim

 

One claim made by some "experts" is that using 10,000 psi repair mortar can fix a deteriorating stem wall affected by rusting rebar. At first glance, it may seem that 10,000 psi repair mortar, being 1,000 psi stronger than the pressure from concrete expansion (commonly known as rust jacking), could address the issue. However, this claim overlooks a crucial factor – the difference between compressive and tensile strength.

 

Concrete's compressive strength refers to its ability to withstand compression or squishing forces. On the other hand, tensile strength represents its capacity to resist being pulled apart or stretched. While concrete is excellent in compressive strength, it is inherently weak in tension. This weakness is compensated for by the inclusion of rebar, which has high tensile strength, in the concrete.

 

The Dilemma of Tensile Strength

 

When rust jacking occurs due to rusting rebar, it exerts tensile forces on the surrounding concrete – opposite to compression. This is where the problem lies. The tensile strength of concrete becomes critical in resisting rust jacking as the rebar inside the concrete tries to split it apart.

 

  

 

Calculating Tensile Strength

 

The typical method of calculating tensile strength is to take 7.5 times the square root of the compressive strength of concrete. For example, if the concrete has a compressive strength of 10,000 psi, its estimated tensile strength would be 7.5 * √10,000 ≈ 750 psi.

 

  

 

The Reality Check

 

With the knowledge of the concrete's tensile strength being around 750 psi, it becomes evident that 10,000 psi concrete is insufficient to resist the 9,000 psi pressure exerted by rust jacking. Therefore, relying solely on high compressive strength concrete is not a viable solution for addressing stem wall deterioration caused by rusting rebar.

 

Overcoming Stem Wall Issues: Science and Best Practices

 

To effectively deal with stem wall problems, it's essential to understand the underlying science and adopt best practices. Solutions may involve using composite stem wall repair systems, implementing well-researched stem wall repair methods practiced in Phoenix, and mitigating the effects of sulfate chloride attack on stem walls.

 

Always Verify the Facts

 

When presented with various solutions, it's critical to fact-check and verify claims independently. As a homeowner, you should be well-informed about the problem and the available solutions before making any decisions regarding your concrete stem wall repair.

 

  

 

In conclusion, addressing concrete stem wall issues caused by rusting rebar requires a comprehensive understanding of concrete's tensile strength and the limitations of high compressive strength concrete alone. By relying on scientific knowledge and best practices, homeowners can effectively tackle stem wall repair and ensure the longevity and stability of their structures.