Notes

step one : Compressive strength is obtained by design, using the cement to aggregate ratio as a base, then adding admixtures for increased strength.
Reinforcing strength is obtained by adding either fiber reinforcing, deformed reinforcing bars (rebar), welded wire fabric, or other optional reinforcing materials.2:
Determine the requirements for your project. For foundations, slabs, and beams, you may simply order a high-strength ready-mix concrete from a ready-mix plant. This product is usually available in standard design mix strengths of up to 5,000PSI. 3:Adjust the mixture you are using if you are mixing your own concrete. An example would be to use more portland cement and less sand for a home made concrete mix. Large aggregate like gravel and crushed limestone do not affect the strength of concrete as much as the cement to sand ratio.4
Use other admixtures like fly ash as a substitute for part of the fine aggregate in your mixture to increase the compressive strength if you like. The higher the cement/fly ash to sand ratio is, the stronger the resulting concrete will be.Research chemical admixtures to find specific chemicals you can purchase to change the properties of your concrete. High-early additives, retarders, and other specialized chemicals are used in industrial concrete to increase its strength and regulate curing times.
Add reinforcing to increase the strength of concrete in your project. Up-sizing rebar, installing multiple mats of reinforcing, and decreasing spacing between bars. wikihow is were i got my information from