Concrete with Small Maximum Grain Size and High Spectrum of Performance

Project Number 284

This research project is based on the successfully completed VGB research project 240 „Fly Ash Concrete with High Amount of Fines“. Using the same working title, it is supposed to support the further development of concrete with small maximum grain size and high content of fly ash for a wide applicability as well as the opening of markets for these concretes.

Due to different environmental conditions concretes can be roughly divided into three performance-related classes for construction elements used indoor, outdoor or in industrial environment. To ensure the durability, the concrete standards (EN 206-1 together with DIN 1045-2) give limits for the minimal cement content and the maximal water-binder-ratio for each of these classes. By the limitation of the maximum grain size to 8 mm and a soft to flowable consistency, the project aims at producing robust concretes with substantial advantages for the workability.

The aim of this research project is the development of an unerring concept for designing concretes with high amount of fly ash and small maximum grain size. The concept should be applicable for all mentioned performance-related classes. Therefore concretes with comparable fresh-concrete-properties, strength and durability will be investigated using six sands with different particle-size distributions, six fly ashes of different origin and three different cements. The experimental program contains the determination of basic material properties as well as tests on the fresh and hardened concretes. The collected data will be systematically analyzed and the results should be transferred into a designing-concept, which is based on characteristics of the basic materials cement, fly ash and sand. Thus the production and application of concretes with high amounts of fly ash and small maximum grain size will be technically and economically controllable for most concrete applications. A pilot construction site is being involved in the research project in order to demonstrate the advantages of the modified concretes in practice and to serve as a reference for the specialised public.

The project is assigned to the VGB research programme "Waste Management of Residues from Coal-fired Power Plants and Waste Incineration Plants" (ERKOM). The project is carried out from 2006 to 2008 by the Institute of Building Materials Science, Leibniz University of Hannover, directed by Professor Ludger Lohaus, and technically supervised by a working group of the Working Panel " Power Plant By-products ". The research project was financed by the German Federal Ministry for Economics and Technology by means of the Working Group of Industrial Research Associations „Otto von Guericke “ e.V. (AiF; AiF-FV-NR. 14617 N).