FTG ENG | eBooks

Inaccurate or incomplete information If you don't have access to accurate construction conditions for cast-in-place concrete, you can't accurately calculate the correct amount of material needed. If your calculations are wrong, you could end up with too much concrete and costly waste, or too little concrete that requires additional materials, time, labor, and equipment—and adds unexpected expenses. Also crucial are accurate dimensions for features like door blockouts, brick ledges, and complex shapes and curves. But if your dimensions are off, you could end up making mistakes that require rework. Uneven slab work Critical to concrete work is making sure your slabs and panels are poured correctly, with flatness, slopes, and openings set according to specifications. Measuring floor flatness is already a time-consuming process to schedule, complete, or receive official reports from testing agencies. If you find problems after the concrete has been poured, tearing out and repouring or leveling slabs or panels adds even more time and can be very expensive. On top of it, the new OSHA silica safety standard—requiring that any concrete cutting, grinding, or chipping be done with vacuums and/or water placement—also takes more hours, equipment, and labor for set up, completion, and clean up. Positioning mistakes and omissions Mistakes in the location of foundation steps and pilasters, anchor bolts poured incorrectly, and missing steel embeds for structure and stair attachments are all too common in concrete work. If you're using a tape measure to position anchor bolts, for example, it can be particularly hard to achieve precision. If any mistakes happen and aren't caught when the concrete is still wet, you could face costly back charges, rework, and reputational damage. Precast concrete issues When precasting concrete walls and panels, you need to be sure door and window block- outs, embeds, rebar, and picking eyes are placed correctly during setup. If materials have been prefabricated based on inaccurate measurements or calculations, the negative impacts can escalate. You could end up paying for additional crew time and equipment like expensive cranes, not to mention refabrication, to make things right. Ideally, there are few if any errors, and those mistakes that do occur are caught early on, resulting in only a request for information (RFI) and/or a change order. But depending on how serious the error is, it could still take a lot of time and effort to correct. If structural components are already in place, the situation only worsens as every delay erodes the project schedule and budget, as well as your profit margin. In the worst cases, errors aren't identified or properly prioritized during construction, compromising the finished structure and creating a potentially catastrophic safety hazard. Some contractors are selected specifically because they can accurately and efficiently set anchor bolts for heavy machinery and steel columns. 4

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