Bleeding of Cement Pastes Modified with the Addition of Granite Powder

The article presents the results of bleeding tests for cement pastes modified with the addition of granite powder. Bleeding is the process of dispensing the water from the inside of the mixture towards the top. Bleeding in cementitious mixes is an important process related to early-age properties of composites (like cracking of concrete slabs). There are known examples of damage to horizontally formed concrete structures due to the uncontrolled bleeding process. The research was performed for four series of modified cement slurries of the addition of granite powder. The test was carried out with the use of a method allowing to obtain high accuracy of measurement (ASTM C243-95 Standard Test Method for Bleeding of Cement Pastes and Mortars (Withdrawn 2001), [1]) of the released water over time, with particular emphasis on the first 30 min of the process. Three phases of the bleeding process were observed during the investigation (initial bleeding, accelerated bleeding, stable bleeding) into cement pastes. An additional division of the first phase on three phases (start of the process, components ordering, appropriate bleeding) was also proposed. The results of the research also present that thanks to the addition of granite powder, it is possible to reduce the volume of dispensed water in the bleeding process. The main issues were recognized and directions of future research area are indicated.