Sand and gravel
The effectiveness of your concrete depends on two factors. It is going to depend on the consistency of the mix, and it is also going to depend on the ingredients utilized in the mix. To that end, you want to make sure that if your concrete mix is working with sand and gravel, that you have both of these things up to the standards of your project. For example, when it comes to sand, you want a concrete mixture that takes advantage of clean sand, since this should prove to be stronger. You will also want to weigh the ratios of sand and gravel carefully.