Fresh concrete is perishable and will lose quality if it sits in the truck too long. ASTM C 94, Standard Specification for Ready Mixed Concrete, says that concrete should be discharged within 90 minutes and before 300 revolutions of the mixer after water has been added to the cement.
You can prevent cavities. Minerals in our saliva, such as calcium and phosphate, along with the protective fluoride that we can get from fluoride toothpaste or a fluoride rinse or in some cases from fluoridated tap water, can repair minerals and protect them from acid damage.
How to Prevent Tooth Decay and Cavities Just as you learned from your dentist at an early age, prevention is the best way to avoid a cavity. There are many measures you can take to help prevent the formation of a dental cavity or other types of tooth decay and damage. The first step in preventing a dental cavity is to start and keep up with a comprehensive oral hygiene routine.