Modification of cement concrete by wood biofuel fly ash

Concrete production is associated with considerable energy consumption. Energy is used in the production of raw materials, binder materials, and in their transportation. Cement manufacture is a massive source of CO₂ to the atmosphere. The abatement of CO₂ emission in cement industry is a priority axis in the European Union and worldwide. Therefore, solutions for minimising the amount of cement in cement concrete are sought. This research aims to replace a part of the cement by wood biofuel fly ash (hereinafter WBFA) in cement concrete and to analyse physical and mechanical properties of modified cement concrete.

The doctoral thesis analyses the characteristics of wood biofuel fly ash and the possibilities of using thein in concrete manufacture. The main objectives are to test the effect of sieved and not sieved wood biofuel fly ash, and the amount of fly ash used as aggregate on physical and mechanical properties of concrete. The aim of the thesis is to find the technique for rational utilisation of wood biofuel fly ash in concrete manufacture.

The doctoral thesis consists of three chapters, general conclusions, and the lists of literature references and author’s publications on the topic of the thesis.

The introduction chapter discusses the research topic, the relevance of research, describes the object of the research, states the aim and objectives of the research, and describes the research methodology, the scientific novelty of the research, the practical value of research results and thesis statements. The introduction chapter ends with the list of author’s publication and conference presentations on the topic of the doctoral thesis and the structure of the thesis.

The first chapter covers the analysis of scientific literature. Scientific research on combustion ash is analysed, biofuel ash generation processes, and utilisation of biofuel ash in concrete is described in this chapter. The chapter ends with the formulation of conclusions and specified objectives of the thesis.

The second chapter describes the materials used for experimental tests and their characteristics. Compositions of concrete mixes used in the tests and formation of specimens are detailed. Research methods used and laboratory instruments and equipment are specified.

The third chapter analyses characteristics and structure of wood biofuel ash. Physical and mechanical properties of hardened cement paste and concrete are analysed in this chapter. Results and analysis of concrete resistance to freeze-thaw cycles are presented. Changes of physical and mechanical characteristics of modified concrete are presented.

Six research articles were published and five presentations in scientific conferences in Lithuania and other countries were made on the topic of the doctoral thesis.

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DOI: https://doi.org/10.20334/2019-030-M