Can you please tell me the shortest length of time the blocks must be in under the tarp and then soaked in water before doing the compression testing?
At the CVBT we test our blocks at 7 days (1 day air curing, 4 days of solar curing [under tarp] and 2 days immersion). We like them to pass 2 MPa strength. Click here for a form to use with our CT2 compression tester. When I built my house I used blocks that had been solar cured for 3 days because I needed them quickly. The main load a wall takes is it's live load from wind. The dead load from the weight of the wall, roof and other static (non-changing) loads is small compared to the live load. Normally, a building will not see a live load until sometime after it is completely built. By then the blocks have had a lot of time to cure and become strong.