Superplasticizers make normal or low slump concrete to a high slump concrete. The resulting high slump concrete often requires no vibration to pour into the form. Higher slump concrete can withstand free fall distances, and are more resilient to segregation when mixed with superplasticizers. They are categorized into Types F and G admixtures, and generally last only 30 min to 1 hr. Type G can generally be re-dosed to increase plasticity.