August 2022: If Concrete Is So Strong…


August 2022
Number 102

From the Desk of Willis

I hope everyone is enjoying their summer so far?! For us it has been really hot, a little dry and very busy. We have quite a heavy work load this summer, as usual, and have a number of projects going of various types and sizes. We are still working exclusively on Brays Island and feel very blessed to be able to work in such a beautiful place and for such great people. 
We have certainly considered expanding into other areas but as of yet have not seen clear to do so. When we make business decisions we don’t just consider what is good for us and our business but, rather, what is good for us, our workers and our customers. Before we expand into another area we have to be sure that we can maintain our level of service to current customers as well as extend that same level of service to any new customers. For us it’s not worth sacrificing quality or service for the potential of a little extra profit.
I often think back to where I came from and how I got to where I am today. I, like everyone else, am where I am today due to the culmination of my life’s experiences up to this point. More precisely though I got to where I am due to my reactions to my life’s experiences. Very rarely do we control the experiences that come our way. The experiences may be as a result of some action we took and we certainly might be able to guide or manipulate the experiences as we have them, but, ultimately, the end result depends on how we react to the experiences we have. My reactions to certain pivotal experiences in my life is what steered me into construction and eventually led us to working on Brays Island. Some of you may have heard the story but for those of you who haven’t here is how I ended up where I am today.
When I was a toddler my parents purchased a house that was nearly 100 years old at the time. Over the course of the next ten years we proceeded to remodel the house from top to bottom. That was the first construction project I was involved in and all of it took place before I was 13 years old. I learned framing, roofing, siding, electrical, plumbing, air conditioning, masonry, carpentry, cabinetry, painting and nearly everything else involved with building a house. I was able to see first hand how old houses were constructed, how to make them new again and how to make new houses better. When we finished the house my parents decided they wanted to move back “home” and work for my grandfather’s business. So, they sold the house and we moved near to where I’m currently living today. My father starting working for the family business and I did as well in the summers between school.
A number of years passed and my father was approached to do a major renovation to another historic home. Around the same time he began building his own new home. This was the year 1999 and I had just graduated high school and started working full-time. We worked closely together on both the renovation and his home and I continued to gain valuable construction experience. However, at that time I thought I wanted to become an electrical engineer. I planned to save up, go to college and get an engineering degree. Construction work was just the way I intended to pay for it. Fortunately, my dad always told us that we could do anything we wanted after high school but we were going to learn carpentry and construction so we always had something to fall back on. My acceptance of (reaction to) this experience prepared me for what was next.
In January 2000 while we were working on my dad’s home he fell from the second floor balcony and ended up with a head injury. He was airlifted out and was in the ICU for 6 weeks and in the hospital for another 6+ weeks. When he got out of the hospital he was still unable to work for several more months. We were in the middle of his home and the renovation and both needed to be finished. My grandfather met with the architect and owner of the renovation and told them that he would not be able to complete the project due to the circumstances. The architect requested that I be allowed to take over and run the job to completion. Everyone agreed to give it a try and that’s what we did. I was 18 years old at the time and with much coaching by the architect and patience by the owner I finished the project 6 months later. (You can see this home on the architect’s website here I had decided during that time that construction was my calling so I began college in the fall of 1999 studying construction management. When I finished college I worked for a year until my grandfather retired and then started Ponds & Sons Construction Company with my dad. A few years later we landed on Brays Island.
During the great recession of 2008 Ponds & Sons went out of business but a year later we started Willis Sinclair Homes. We diversified our business and began offering a wider variety of construction services. We reacted to the recession by structuring our business to better withstand hard times in the future. Now with many years under our belt we look at “bad” experiences as opportunities for improvement and advancement, no matter what it is or how unpleasant. Several times I had the chance to react poorly to difficult experiences but if I had I would likely not be in construction on Brays Island or anywhere else for that matter. I thank God for how I reacted to those experiences and for giving me the strength to persevere!

If concrete is so strong, why is steel embedded in it?

Concrete is a very versatile building material. It is easy to use (from a theoretical point of view – actually working with concrete is hard work physically). Concrete can be shaped with relatively easy-to-build forms. Once it sets or cures — a chemical reaction — (concrete does not really “dry”), it is strong, durable and weather resistant.

If concrete is so great, that brings up the question, “Why do you place steel in concrete?”

To understand the answer to that question, there is some background you need (or may have). Basically, there are four kinds of forces or loads that materials face: compression, tension, shear and torsion. The first two are the major ones we need to consider for our question.

Compression is how resistant an item is to being squeezed or compressed. Concrete ranks very high in this category. Actually, the only force where it is very strong is compression.

Tension is how resistant an item is to being stretched or pulled apart. Here concrete is a bit lacking. Typically concrete’s strength in tension is about 10% of its strength in compression. Since concrete is significantly weaker in tension, it needs help. Fortunately steel is very strong in tension and compression. If steel is embedded in concrete, the combination of the two results in a material that has both excellent compression and tension qualities.

For completion:

Shear is a force that tries to cut a material (such as a paper cutter or scissors exert).

Torsion is a twisting force.

Concrete (at least in construction projects) is seldom, if ever, subject to shear or torsion forces.

As another aside, if steel is strong in both compression and tension, why is it not used instead of concrete? Actually, there are several reasons including cost, weight. Steel is much more difficult to form or shape than concrete.

If you consider a beam that is carrying a load, the beam will tend to flex (sag) as the load increases. When a beam flexes, the top of the beam is put under compression and the bottom of the beam is being stretched or is under tension.

Remember tension is where concrete is weak, so if you were to enhance the tensile strength (resistance to tension) of concrete with steel, where should the steel be placed in the beam? Not at the top because concrete is already very resistant to compression forces, but at the bottom where there is tension and concrete is weaker. If you look in footers, you will notice the steel in them is near the bottom, just as you would expect. (Code requires the steel be embedded three inches inside concrete, so it is not completely at the bottom.)

If the steel is closer than 3″ from the edge of the concrete, small cracks in the concrete may allow water to reach the rebar. Water will make the rebar rust and weaken. This may be what caused the collapse of the high rise in Florida a few years ago.

The above photo shows where a concrete footer will be poured on a home we are building. Notice the horizontal steel is near the bottom of the trench. It is supported with concrete “brick” to keep it the required distance from the edge of the concrete. The vertical steel is to tie the foundation wall to the footer.

The steel used for construction projects is called rebar (short for reinforcing bar). Although concrete adheres well to steel, rebar has ridges to make the bond even stronger. When you combine two materials (such as steel and concrete) you have to be careful they both expand and contract about the same as temperature changes. Fortunately the coefficient of expansion for steel and concrete is very close.

When rebar is placed, often it is tied together with small wire. You might wonder how a small piece of wire could add any strength, but the only purpose the wire serves is to hold the rebar in position until the rebar is embedded in concrete.

Rebar used in typical residential construction is made of high carbon steel. The ridges are formed by rolling the the rebar when it is heated. The ridges form an additional mechanical bond between the concrete and steel. 
Rebar is sized (in America) by the number of 1/8 of an inch increments in the diameter. Number 4 rebar would be 4/8” (or ½”) in diameter. Typically we use either #4 or #5 (5/8”) rebar in our construction projects depending on the structural prints.

On one of our trips West, we stopped at the Minuteman Missile National Historic Site in South Dakota. The ranger pictured is holding a short piece of rebar used in the construction of the underground missile launch center. The rebar was #16 (2 inch).

A steel mesh is often used in slabs to keep cracks small and to tie concrete together if (when) it cracks. The mesh is usually designated by its size. 6×6 is mesh that forms 6″ x 6″ squares is often used in residential projects. 

This is a slab we poured a few years ago. It has 6×6 mesh in it. Notice the standoffs to hold the mesh off the plastic. As the concrete is poured, the mesh is hooked and pulled up so it is totally embedded in the slab. 

When we build your home, we will make sure everything is done well. The county requires periodic inspections (after certain tasks are completed), but an inspector cannot catch everything in a short inspection. That is why we are on your site regularly and watching everything. 

Do you have any questions? Don’t hesitate to ask. We can help. No cost or obligation for you, of course. 843 846 2500 (voice or text) or

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