The four main ingredients of concrete are sand, aggregate, cement, and water. Mixing these together and allowing the process of hydration to occur will end up creating concrete but there are many products that can be added to the mix to change the hydration process. These products can change the strength or initial set time. One commonly used admixture is simple calcium-chloride or better known as salt. This product added to the mix will create heat and will shorten the curing time and is typically used in cold weather. There are retarders that will do just the opposite and lengthen the time to set. This may be used in very hot weather or when the concrete must sit in the truck for a very long time to get to the site. There are superplasticizers that reduce the water content and strengthen the concrete along with many other admixtures. Concrete is not as simple as it may seem.