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Polymer-silicate composite based on alternative raw materials under conditions of increased temperature
(Elsevier, 2016-08-03) Melichar, Tomáš; Bydžovský, Jiří
The paper presents research into studying the properties of composite materials with polymer-silicate matrix and porous (lightweight) filler. Specifically, the matrix based on cement substituted by 35% of alternative raw material was considered. In case of filler aggregate based sintered ash was used. Investigated materials were exposed at high temperatures. Thermal loading took place gradually in temperature increments of 22 °C (reference conditions), 400, 600, 800 and 1000 °C with subsequent controlled cooling. Attention was also focused on various ways of cooling – slow in the furnace (1 °C/min) and immersion in water (bath temperature c. 18 °C). Suitability of matrix modification and use of porous fillers based on alternative raw materials was proved by set of analyses. After exposure in an environment with a temperature of 1000 °C followed by quench cooling was set residual compressive strength of about 40%, which is relatively high for this type of the matrix. The curves of residual strength with different types of cooling are intriguing too. Selected samples were also investigated by using micro/structural techniques, where the emphasis was placed on the formation of any defects related.
The FBC ash as a hydraulic ingredient of hydraulic lime
(Elsevier, 2017-01-31) Dvořák, Karel; Kulísek, Karel; Gazdič, Dominik
This work is focused on the possibilities of utilization of ashes from fluidized bed combustion, i.e. FBC ashes, for the manufacturing of hydraulic lime. Alternative hydraulic binders are becoming very popular in the present due to requirements on reducing CO2 emissions. FBC ash is an easily available, though not easily usable raw material. Because it has several hydraulic characteristics, it can create a hydraulic binder together with lime. Mixtures of hydrated lime and FBC ash from filters and from a bed were prepared in this work. The main criterion was the hydraulic modulus. The physico-mechanical properties were observed and were compared with the reference sample, which was hydraulic lime from industrial production. The prepared hydraulic limes achieved similar parameters as commercially manufactured hydraulic limes or lower strength class cements.
Composites Based on Alternative Raw Materials at High Temperature Conditions
(Budapest University of Technology and Economics, 2017-10-24) Melichar, Tomáš; Bydžovský, Jiří; Dufka, Amos
This paper presents newly developed polymer-cement composites. The primary binder (cement) was partially substituted by use of blast-furnace slag and high-temperature fly ash. A lightweight aggregate – agloporite (grain size in range 1–2 mm) was used among other components. This porous aggregate is produced from energy by-products (fly ash). Attention was focused on the behavior of the composites when exposed to elevated temperatures (400 °C–1,000°C). The influence of several different methods of temperature decrease was assessed – slow (in furnace 1°C/min) and rapid (laboratory ambient 22°C and water bath 18°C). Specific dimensional changes were determined, including strength characteristics and bulk density.
The microstructure of a cement composite based on a secondary raw materials
(IOP Publishing, 2018-07-16) Figala, Petr; Drochytka, Rostislav
Waste management and its use as a secondary raw material is a matter that is being given increasing attention. Such raw materials also include waste products from the energy industry or municipal waste disposed of from the recycling process. This study explores the use of secondary raw materials in specific cement–based cement composite as a partial binder substitute. Selected secondary raw materials were pre–treated by grinding to a specific surface of 300 and 500 mkg. As a reference material, a commercially available mixture was selected to produce cement composites intended for the environment with high physical–mechanical demands. Cement was substituted by secondary raw materials at a rate of 20 and 40% in the reference recipe. Basic physical–mechanical characteristics such as compressive strength and tensile strength at bending were determined on standard 160×40×40 mm prisms. Strengths were determined after 3 and 28 days of ageing. In addition, the influence of binder substitute by the admixtures on the microstructure of cement stone was monitored by sample scanning using an RTG tomography. The positive effect of a part of the binder substitution by selected secondary raw materials on microstructure was proved in all tested samples. From the measured data, it is evident that the higher specific surface of the pre–treated admixtures did not have a significant positive effect either on strengths or the microstructure.
Effect of firing temperature on the structure of the aggregate from sintered ashes
(Elsevier, 2016-08-03) Černý, Vít; Tůmová, Eva
Production of artificial aggregate from ashes is worldwide known technology that uses up to 100% of ash in the mixture. There are known two types of aggregate. First is based on binders and known as cold-bonded. Second type of aggregate is produced by self-firing process that uses a content of combustible substances in the mixture. After ignition this fuel generates enough energy for the sintering process. The paper gives an account of the influence of parameters of ash and conditions of firing on the quality of ceramic body made from ash. Temperatures of 1050 °C, 1150 °C and 1200 °C were examined. The research focused on the structure of the ceramic body as well as its physic-mechanical parameters. The results show also that firing temperature is essential for forming the structure. An important indicator is the share of melt that form a solid ash body.

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