![]() You should be able to see individual grains of sand. Look at the mortar very closely, even with a magnifying glass. You'll want to pay attention to the existing mortar in the wall near where the failed block are located. Wouldn't it be nice if you could just go grab the extra ones the builder left behind? This is a perfect example of why I always tried to order a few hundred extra brick or block for my jobs and leave them behind for the owner. The key is obtaining concrete block that match in color so the repair doesn't stand out like a sore thumb. The repair process is not too hard at all. If that was the case, the mortar would probably be rotten as well. The fact that the mortar in between the block is still there and in great shape tells you that it's not just a simple matter of the wall getting wet and then repeated freeze / thaw cycles blew it apart. I could go on and on with other possible causes, but those are the top ones I feel might be the cause. If concrete is not cured correctly it never attains its design strength. This water is required to fuel the continuing hydration chemical reaction that causes the billions of microscopic cement crystals to grow and interlock with the sand and rock. It's also possible the failed block were not cured properly and the water in the block evaporated too quickly. That extra water can dilute the amount of Portland cement in the mix. It's possible that the batch was mixed correctly but extra water was introduced into the block that are deteriorating. It could be that when the concrete block were made, that portion of the mix didn't get thoroughly blended. There are many possible reasons why the concrete block crumbled and it's virtually impossible to point to the smoking gun. Nothing says you can't add more cement to get to 5,000 or 6,000 PSI! The current minimum requirement for exterior concrete is to make it so it's a six-bag mix or tests out to 4,000 pounds per square inch (PSI) of compression strength. In the case of the railroad bridge abutments that are over 100 years old and in great shape, I'm sure the reason is because the builders added extra Portland cement to make it extremely strong. All the ingredients are important, but only one is responsible for the long-term durability of the concrete and that's the Portland cement. The most basic concrete has just four ingredients: rock, sand, water and Portland cement. To understand why some concrete can last so long and other crumbles in a short amount of time you just need to think about how concrete is made. With minimal effort, I can show you concrete walls built by railroad companies that have been exposed to harsh winter weather and the walls look much like the day they were poured. Your builder's statement about it lasting at least 100 years is not far off when you look around you. It's artificial rock when you think about it. Photo Credit: Marty S.Ĭoncrete block is a great material when it's made correctly. Some of the concrete blocks in this wall are beyond repair.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |