Concrete with Small Maximum Grain Size and High Spectrum of Performance - Composition and Properties

Project Number 240

In the last years, the developments in concrete technology concentrated on high-performance concretes, high-strength concretes and self-compacting concretes in particular. The main focus with these concretes is the amount of fine particles and the smaller maximum grain size.

High-performance concretes are limited to a small range of applications. Innovative approaches from research and developments have not been related to normal concretes, which are used in more than 90 % in the building industry, yet.

In the research project normal concretes with smaller maximum grain sizes and a high amount of fine particles will be developed. In order to avoid high cement contents, fly ash is taken into account as cement replacement at the upper limit of existing rules as well as the authorised approvals concerning individual construction projects (approval in single cases). The advantages of fly ash regarding workability and strength can perfectly be used for the production of such concretes. A decrease of the maximum grain size has to aimed at for the developing of a robust concrete while forcing a balanced grain size distribution.

The research project will demonstrate the properties of fly ash concrete containing high amounts of fine particles by exemplary trials and will prove the properties of such concretes. For the production of these concretes, two sands with different grading curves, three fly ashes of different origin, a cement and a plasticising agent will be used and the properties of fresh and hardened concrete will be tested.

The project is assigned to the VGB research programme "Waste management of coal-fired power plants and combustion plants" (ERKOM). Starting in 2003, the project is carried out by the Institute for Building Materials at the University of Hannover and is technically supervised by a working group of the working panel "Power Plant By-products".