Structural inspection and repair are extremely important topics. Building materials require regular inspection, maintenance, and repair, regardless of whether they are wood, steel, masonry, or reinforced concrete. This article will discuss the degradation of masonry, concrete, and repairing structures. Structures require regular supervision, here are a few things to look out for.
Masonry and brick make for marvelous and intricate walls, but they face a number of issues due to thermal expansion and water intrusion. As bricks expand and contract as with weather changes, hinges can form. Hinges are cracks in masonry where wall begins to sheer off due to thermal expansion, often occurring around corners or between façades. Bricks are smallest after being fired and expand through their lifespans from absorbing moisture.
This moisture can cause large damage and deteriorate the masonry in the façade. Water can freeze inside the brick and cause spalling (where fragments of the larger solid body fall off). Trapped moisture can also expand by becoming a vapor, growing 1500 times in volume and applying around 4 pounds per square inch (PSI) of pressure inside the brick and masonry. Osmosis is another issue water can cause in masonry. When absorbed water evaporates, it can leave dissolved mineral salts which crystalize and expand in volume at 3000 PSI.
Bricks can be inspected visually, but they must be viewed internally as well to get a full picture. Inspections can be done with sounding hammers, bore scopes, and minimally invasive inspections where a brick is removed to see what is behind it. Don’t be afraid of small portions of the wall being dismantled, this can help in finding leaks, but it must be patched at the end.
Masonry repairs can be done with calk, but calk cannot solve major issues. Calk and other sealants can help for a time, but eventually problems may grow enough that a full replacement is required. This is especially true in older buildings, before the use of expansions joints. These old bricks have contracted and expanding over the years, and cracking and hinging can sheer off large portions of the masonry if left alone.
“All concrete cracks,” Scott Weiland PE, SE, with Innovative Engineering Inc. said. “Engineers older than me say that there are two kinds of concrete, concrete that is cracked and concrete that is going to crack.” Concrete is a major building material, and reinforced concrete is one of the most ubiquitous and useful materials in construction. Concrete is a composite material composed of aggregates (such as volcanic ash or silt) bonded with fluid cement. The cement is reinforced with a steel bar in its core, increasing tensile strength immensely.
Reinforced concrete is an excellent building material, but it will deteriorate over time. Carbonization and water damage are common problems, both of which can occur over extended periods. “Its important to keep in mind that something that looks innocuous, if left for years and years, can accumulate and build to become a dangerous, expensive liability.” Explained Evan Moore, PE, SE, of Engineering Restorations Inc.
Carbonization occurs as oxygen in the air affect concrete over extended periods. Carbonization causes the concrete to become more porous, and this allows water and moisture to seep through and accumulate in the steel reinforcement. This causes all the issues of rusting and corroded steel, in the core of a reinforced pillar, support, or beam. The deterioration of the steel in reinforced concrete can lead to spalling, delamination, cracks and more.
Carbonization can be checked through Chloride Ion testing. This is done by drilling into the concrete or coring it and measuring the pH of the dust with a solution. The steel core can be tested using sounding hammers or an impulse echo, both of which structural engineers are normally trained to use.
Reinforced concrete has multiple repair methods, such as fill in place, form and pump, and hand application. A method used when repairing large overhead areas is the messy, difficult, but extremely interesting spray application. This method involves spraying concrete from a nozzle and is similar in appearance to applying sprayed insulation in a house. This is just one of many ways to fix concrete, but each repair method requires a few steps in their execution.
Once an issue is identified, it needs to be addressed. Some problems are easier to solve than others, and some do not even require a repair, only observation. These solutions can be found through a licensed structural engineer in conjunction with a contractor or other group to execute the repair.
“Find and fix the cause of that crack, if you don’t fix the underlying issue, you’ll repair that crack and another will show up just a few inches away,” Weiland added.
Finding a crack, delamination, or spall is only the first step, you must identify the problem itself. Once the issue has been identified, you can begin to develop construction documents with a licensed engineer, preferably the one who completed your inspection and help locate the problem.
After preparing construction documents, contractor bidding can begin, and the contract type can be selected. Contract types can range from lump sum contracts to contracts time and materials. Once everything is set and the contractor, engineer, and owner sign off on the work, the repairs can begin.
Repairs can be highly disruptive to business, and this must be accounted for when planning a repair. A building or parking deck may become inoperable during a repair, but it is better for a building to be temporarily inoperable than permanently. During the repairs, documentation for what is done and where are extremely important. This will help with future repairs and inspections and can give owners a head start when beginning the process for future inspection and repairs.
This article is but a brief overview of the many considerations that go into building inspection and repairs. Always consult with a licensed engineer regarding building inspections and repairs. For more information, check out the Structural Inspection and Repair Guide, available for free under Books / Blogs on CRE Insight Journal.
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