COMPARATIVE STUDY OF DIFFERENT FLY ASHES: CHARACTERISATION AND PERFORMANCES

In the last decades, the use of fly ash and other waste materials in the production of concrete has had a widespread diffusion, above all in response to environmental and economic issues. High volume fly ash concrete, in which even 50% cement can be replaced by fly ash, was first introduced by CANMET in the late 80's; a deep understanding of these materials seems necessary, in order to support their use. This study presents an overview of the characteristics and behaviour of four types of fly ash, different in composition (Class C and F) and fineness. They have been investigated both in terms of chemical and physical characteristics and in terms of performances in mortar, with and without superplasticizer. Furthermore, some mercury porosimetry analyses have been undertaken on hardened mortar specimens in order to study the effect of fly ash on the microstructure development. An attempt has been made to correlate the water demand and the strength development of mortars to the chemical analysis and fineness of the fly ashes, as well as to the porosity of the hardened mortars. The aim of this work is to highlight the kind of fly ash and admixture which can better support an extensive use of these waste materials in the production of concrete.

• INTRODUCTION

• EXPERIMENTAL DETAILS

• RESULTS AND DISCUSSION

• CONCLUDING REMARKS

• REFERENCES