Olegus wrote:Не успели сдать дом, а в бетонном патио появилась трещина. Не ужас-ужас что, но змеится тоненьким ручейком фута на три. Похоже, просела земля и бетон не выдержал. Считается ли ето достаточным условием для переделки здесь или такое сплошь и рядом и никто внимание не обращает?
заранее извиняюсь за английский но за неимением времени/навыков печтания по русски пишу как есть.
I am a senior engineer in a company specializing in concrete pavements and slab on the grades (ground) design/evaluation/forensics. what you are describing in your topic is likely a constuction-related problem resulting from the improper cure or improper mix design. These cracks are not due to the settlement for sure. There were no time nor right conditions to cause the settlement. The weight of the slab per inch of ground is not that heavy and is distributed evenly across the slab.
Concrete mixed and placed in the field should be wet-cured for the first 28 days otherwize it will have surface cracks due to excessive shrinkage of the top layer during curing time. the same cracks could show up if there was not enough water in the mix. Usually, these cracks are not deep (about 1/2 inch) and as long as the distance of the concrete between the cracks is less than 12 feet will not open with time. So the contractor is partially right. However I am very surprized that knowing the local conditions he did not do anything to help the curing process.
concrete slabs without reinforcement placed on the grade (ground) will develop cracks across any side that is longer than 15 feet due to temperature differentials between day/night and slab curling phenomenon. to avoid that, a joint should be placed to releave the tention or a proper reinforcement and cure should be used during constuction.
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