Introduction

Since 2003, when close cooperation was established between the Department of Glass and Ceramics, ICTP, and the Department of Construction Technology, FCE CTU in Prague, research on the exploitation of fly ash emissions from large furnaces has been running based on previous several-year research into alkali activation performed at the Department of Glass and Ceramics. The objective of cooperation is the application of research results obtained in this way in construction practice.

POPbeton? is a new type of cement-free concrete with a binder consisting exclusively of fly ash. As the existing common term of fly-ash concrete stands for cement-based concrete with fly ash admixtures as a fine inert component complementing the filler, this new type of concrete has been named POPbeton / POPconcrete. POPbeton? has ambitions to become a new construction material reusing some other waste materials such as slag, metakaoline, fine glass waste, as well, or a material for the solidification of some hazardous wastes.

The programme of the exploitation of fly ash emissions from large furnaces is a follow-up to the programme running at the Department of Glass and Ceramics, which has been engaged in research of geopolymer reactions for many years. The objective of cooperation is the application of research results obtained in this way in construction practice. The whole programme is particularly focused on the exploitation of brown coal fly ashes, which are produced in our country in volumes many times exceeding those of black coal fly ashes.

As was confirmed by the tests, activated brown coal fly ash is less reactive, and the resulting mix has worse properties than a mix where only black coal fly ash is used. The verifying tests performed on black coal fly ashes manifested higher fly ash reactivity and thus better resulting properties of POPbeton, comparable or superior to the results achieved abroad. Due to the variety of fly ash types produced in the Czech Republic, however, brown coal fly ash, or potentially a mix of both fly ash types with a composition corresponding to the ratio of both fly ash types produced, remains our priority for POPbeton?.

The principal advantage of this material, therefore, consists in reducing the ecological burden on the environment by reusing waste materials. This is also connected with favourable prices of input materials, more cost-effective in comparison to traditional concrete binders. The persisting disadvantage is the necessity of tempering fly ash together with alkaline activators to set off fly ash activation. For this reason, after the verification of the basic properties of POPbeton activated by tempering, the research was further oriented towards a possibility of activating fly ash without the need for its tempering.