Hello! This morning, the foundation slab was poured for my house (a semi-detached house, approximately 135 sqm (1453 sq ft)).
The concrete was spread over the reinforcement mesh by the workers. Afterwards, a device similar to a vacuum cleaner (blowing air??) was used. Then, one worker created a grooved pattern in the concrete using a rake, resulting in small waves or a textured finish.
Unfortunately, cracks appeared this evening. Some are over 75 cm (30 inches) long, and some are wider than 3 mm (0.12 inches). Now I’m not sure if these are problematic or not. Concrete is still something new to me. Interestingly, these cracks appear where the concrete is smooth. About 40% of the foundation slab has no grooving. Next door, another house was built at the same time using the same method. There, the entire slab was given the textured finish, and no cracks have appeared at all.
I contacted the site manager, who remained calm and said that this can happen sometimes. He will personally inspect it tomorrow morning.
Are these what are called surface spider cracks?
Are they a cause for concern?
Are there methods to repair them?
I called the site manager directly to ask if I should do anything (for example, add water). He said that is not necessary. The morning was a bit rainy, but from midday it was sunny with about 24°C (75°F).
I look forward to your replies!!! Thank you very much in advance!
Alex
The concrete was spread over the reinforcement mesh by the workers. Afterwards, a device similar to a vacuum cleaner (blowing air??) was used. Then, one worker created a grooved pattern in the concrete using a rake, resulting in small waves or a textured finish.
Unfortunately, cracks appeared this evening. Some are over 75 cm (30 inches) long, and some are wider than 3 mm (0.12 inches). Now I’m not sure if these are problematic or not. Concrete is still something new to me. Interestingly, these cracks appear where the concrete is smooth. About 40% of the foundation slab has no grooving. Next door, another house was built at the same time using the same method. There, the entire slab was given the textured finish, and no cracks have appeared at all.
I contacted the site manager, who remained calm and said that this can happen sometimes. He will personally inspect it tomorrow morning.
Are these what are called surface spider cracks?
Are they a cause for concern?
Are there methods to repair them?
I called the site manager directly to ask if I should do anything (for example, add water). He said that is not necessary. The morning was a bit rainy, but from midday it was sunny with about 24°C (75°F).
I look forward to your replies!!! Thank you very much in advance!
Alex
K
Knallkörper28 Jul 2017 13:05The cracks sometimes appear too wide to be typical shrinkage cracks. In my opinion, the acceptable crack width depends on many factors. You could ask your contractor for a written assessment based on the relevant building codes. Was the fresh concrete left uncovered in the rain?
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