Revision history [back]
Hi Lloyd. While the mix ratios are important for strength, so is the quality of the sand, aggregate and cement. Dirty sand, weak aggregate and low quality cement will all weaken a mix. The quantity of water is also very important, see comments above. Peter Stern suggesty 1;2:4 mixes for slabs without giving any strength. You mention 3,500 psi but do not say whether this is working or ultimate strength - and I assume compressive load... Please advise