Structure development study of porous concrete with fluidized-bed combustion ash admixture

journal article in Scopus

English

Because of its correlation between compressive strength and density, autoclaved aerated concrete (AAC) is a very suitable building material for many applications. Optimal macrostructure of the AAC skeleton is composed by small air pores. On the other hand, the well grown crystals of 11 Å tobermorite represent the most important part of the microstructure. The mineral is formed in hyper-alkaline, hydrothermal environment of the CaO – SiO2 – Al2O3 – H2O system. The main objective of this article is to study the influence of the fluidized bed combustion ash, as gypsum and partially lime alternative. Ground quartz sand, with an admixture of fluidized combustion ash, was used as the initial silica material. In order to reach the Ca/Si molar ratio of 0.73, the main silica sources were mixed together. As the instrument for the hydrothermal synthesis, carried out in the saturated steam environment at the pressure of 1.3 MPa and 185 °C for 12 hours, a laboratory autoclave was used. As the parameters determined to analyse physical-mechanical properties of the samples, density and compressive strength were chosen. X-ray diffraction method was used to observe the growth of the main mineralogical phases and scanning electron microscope (SEM) was used for crystal observation. From the results it is apparent that the fluidized bed combustion ash had a significant influence to tobermorite crystallization and formation.

Autoclaved Aerated Concrete (AAC), Calcium silicate hydrates (CSH), Fly Ash (FA), Quartz sand, Fluidized Bed Combustion Ash (FBCA), hydrothermal reactions, tobermorite, katoite, sulfate admixture, Rietveld refinement

ČERNÝ, V.; MELICHAR, J.; FLEISCHHACKER, J.; DROCHYTKA, R.

18. 12. 2017

1804-0195

Waste forum

2017

4

Czech Republic

267

275

9