Improving properties of fibercement mixtures

Fibrecement is a composite material made using sand, cement and fibres invented in the late 19th century. Fibrecement plates generally used for various interior and exterior applications as a smooth, flat surface for cladding, partitioning and edging. The use of fibrecement plates in construction industry is increasing due to its advantages over traditional materials. In this thesis in order to investigate factors affecting durability and mechanical properties of fibrecement plates inert materials, fibres and supplementary cementing materials (SCMs) are used. As an inert material quartz sand and diatomit, as a fibre cellulose and polypropylene fibres and as a supplementary cementing materials fly ash (FA) and ground granulated blast furnace slag (GGBS) are used as partial replacement materials to the binder and mass measurement, consistency, sorptivity, compression strength, flextural strength and carbonation experiments were carried. Diatomite has much lower density and has smaller fine particles compared to quartz sand. The experimental results using quartz sand and diatomit indicated that the increase in the partial replacement levels of diatomite resulted in a significant decrease in the total mass of fibrecement plates and increase in compressive and flextural strength. Durability characteristics such as sorptivity and resistance to carbonation are improved considerably with the use of diatomite. The experimental results using cellulose and polypropylene fibres indicated that increase in volume of cellulose and polypropylene fibre increased compressive strength of fibrecement plates and especially flextural strength of fibrecmenet plates when polypropylene fibres were used. Another result using fibres in sorptivity experiment is fibrecement plates produced with cellulose fiber showed low sorptivity than plates which produced with polypropylene fibers. At last, the experimental results using fly ash and ground granulated blast furnace slag indicated that the increase in the replacement levels of both FA and GGBS resulted in a systematic decrease in the short-term compressive strength but increase resistance to carbonation of fibrecement plates. With this result, a long-term study is determined to investigate the development of the compressive strength of fibre cement plates using SCMs. Effects of curing conditions to compressive strength of fibrecement plates which includes %100 diatomit and granulated blast furnace slag also investigated by comperison of plates which are cured in normal laboratory condition, under water (22°C) and under hot water (40°C) and results showed that plates cured in hot water gave highest compressive strength. The major factors that affect the durability and mechanical properties of the fibre cement plates are studied in this thesis. The author strongly believes that the results generated throughout the thesis have important practical consequences in terms of producing light weight, more durable and high strength plates as well as supporting more sustainable production of these plates using SCMs. Keywords: Diatomite, durability, strength, supplementary cementing materials, fibre