Is your quarry dust stored in a silo ? If so, maybe when they came to uload,the delivery person unloaded the dust into your cement silo. This has happened to me, but it was slag.
Another reason for your low strength could be your cement powder. Cast some cubes using just the cement powder, and contact your cement supplier. You may have got a couple of bad loads of powder.
with 600 kg. of cement, you should be getting more than 40mpa in 28 days. Try looking at your course and fine agg. To me it sounds like your aggregates are to dirty. start there and also check your testing procedures and sample handling.
Sorry, I forgot to tell you the specs for these cassons is 25 mpa. I would like to use a 20mpa footing mix with 40 to 50% slag . Iam I asking for trouble? Thanks
Due to tight compettion, I would like to use a 20mpa footing mix with 40 or 50 % slag. for piles and caissons. Is this aking for trouble I would appreciate your opions on this. Thank - you .
