Surface Blemishes
Surface Blemishes
(OP)
Do you have any other name other than surface blemishes? And possible reasons please...
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RE: Surface Blemishes
RE: Surface Blemishes
Possible plastic shrinkage cracking.
RE: Surface Blemishes
Vertical elements normally have a higher slump and lower aggregate specified.
RE: Surface Blemishes
Basic things to remember
1. pour the concrete within 1.5 hrs if you use admixtures.
2. place the concrete in layers not more than 50 cm and compact it properly using needle vibrators.Then place the next life within 1.5 hrs -2 hrs so that there is proper bond between the layers and compact it again. If you take too much time you will see cold joints later.
3. The slump at site should be atleast 100 mm for workability.
4. Curing is very very important in the strength gain of concrete and for the surface finish.
5. For finish use long clean smooth finished battens.Most of the masons sprinkle the water over the surface to make it more workable and easier to finish.
If you keep these things in mind then you shouldn't have any problem. If you are practicing this and you have problems then maybe you can disclose us your mix proportions of the concrete.
RE: Surface Blemishes
RE: Surface Blemishes
Go back to the lab and try the mix with reduced w/c ratio and fix the admixture dosage as per the requirement.
Schmidt rebound test only gives you a rough idea about the strength of the concrete at the surface. Also you should calibrate it with the concrete of the same grade in your lab and then compare the results at the site.This is what I would do instead of relying on the manufacturers reference graph.
RE: Surface Blemishes
RE: Surface Blemishes
1. Check condition (surface) of the formwork,
2. Check admixute compatibility in mix concrete,
3. Check how long was it (whether it was?) compacting.