What are recommended mix proportions for good concrete ?

Good concrete can be obtained by using a wide variety of mix proportions if proper mix design procedures are used . A good general rule to use is the rule of 6 's:

• A minimum cement content of 6 bags per cubic yard of concrete , 
• A maximum water content of 6 gallons per bag of cement 
• A curing period ( keeping concrete moist ) a minimum of 6 days , and
• An air content of 6 percent ( if concrete will be subject to freezing and thawing ) .