2/9/2024 0 Comments Concrete block rebar![]() You want to use smaller pea gravel because the void spaces in the concrete block wall are not too large once mortar oozes in between the block and the steel is in place. The rocks used in concrete mixes are responsible for much of the strength concrete achieves once it's cured. The reason you want to use the pea gravel concrete instead of mortar is it's stronger. I then dropped the long steel bars from above down to the top of the footer so the steel pieces overlapped. I did this on all my jobs making sure the steel rods protruded up from the concrete footer about 2 feet. It's a best practice to use this same reinforcing steel to connect the concrete block walls to the poured concrete footer. Once your contractor mixes up small pea gravel concrete, not the sandy mortar he used to lay the block, and pours it into the block voids along with the long steel rods, the concrete block then starts to resemble reinforced poured concrete. ![]() This face of the 2x4 was carefully staked out and represents the CENTER of the wall. You'll see a flat 2x4 up in the air in a straight line. Then watch at 1:10 to see how they got the vertical steel in the PERFECT location. The first 20 seconds of this video show you how steel needs to be in the CENTER of the voids of concrete block. That means it fails or tears apart once you apply 40,000 pounds of pulling force to it. For example, common one-half-inch reinforcing steel on a residential job site may be rated at 40,000 pounds of tensile strength. Steel, on the other hand, has fantastic tensile strength. You commonly hear them talk about the tensile strength of a building material. Engineers and technical folk call those bending or stretching forces tension. I only did it on rare occasions myself to hit a mission-critical deadline.Ĭoncrete, mortar, and almost all rock are very strong when you compress them, but these materials usually only have one tenth the strength when you try to bend or stretch them. Someone may have goofed up and put sideways pressure on the pier before the concrete and steel could be added. Realize he may have been getting ready to do this just before the accident occurred. Your contractor should have filled the hollow spaces in the block with pea gravel concrete and steel bars. Bees fill the void spaces of the honeycomb with honey. When laid on their side and stacked in an offset manner they resemble, to a degree, a honeycomb made by a hive of bees. The vast majority of concrete block are hollow. Most masonry products, including concrete, only have 10% of the strength in tension as they have in compression.ĬLICK HERE for FREE & FAST BIDS from local brick and block masons. But if you try to bend or stretch it, that's tension, it's very weak. The mortar in between each course of block is strong if you try to squeeze, or compress it. ![]() The seemingly minimal force at the top of the ladder was multiplied at the base of the pier where it fractured. The ladder placed against the top of the pier converted the pier to a lever. The block piers toppled over because the connection between the mortar and the concrete block is not able to resist the force of being pulled apart. You need to direct that attention to the contractor on your job and any written specifications that were part of your blueprints and plans. It's strong, it can be used in any number of ways, and it is used in all sorts of residential, commercial and industrial applications. Have you built with concrete block successfully? What did you do? Alan T., Charleston, SCĭEAR ALAN: Let's start out by reassuring you that concrete block is a great building material. Why did this happen and what could have prevented it? I thought concrete block was the smart product to use for my foundation and home, but now wonder if I made a big mistake. The one pier crashed into the second one.
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