Increased reactivity

Using a glass-containing metakaolin as an active filler in lime-based binder systems

Summary: In this project the suitability of a glass-containing metakaolin (Metapor®) ­supplied by Dennert Poraver GmbH for use as a reactive filler for a commercially available lime-based binder system was studied. The findings obtained with six different mixtures show that the mechanical properties such as flexural and compressive strengths as well as shrinkage can be significantly improved with the addition of Metapor®. No negative ­phenomena in respect of a possible alkali-silica reaction were observed. Based on these ­findings, the product Metapor® therefore seems suitable as an active, pozzolanic filler for special binder systems on the basis of hydrated lime.

Binder systems based on hydrated or slaked lime Ca(OH)2 have been known since ancient times. Their key features are high permeability and compatibility with limestone and other natural building materials. On the other hand, however, such binder systems are porous and their mechanical properties, e.g. strength and chemical resistance, tend to be limited [1]. To improve these properties, alternative materials can be used. The partial substitution of hydrated lime with metakaolin is one possible alternative [2]. Metakaolin is used to describe an amorphous, reactive, pozzolanic material formed...