Characterization of Cellulosic Fibers by FTIR Spectroscopy for Their Further Implementation to Building Materials

Nowadays, the material recycling is a growing trend in development of building materials and therefore using of secondary raw materials for production new building materials is in accordance with sustainable development in civil engineering. Therefore, it is increasingly becoming crucial to accelerate the transition from application of non-renewable sources of raw materials to renewable raw materials. One fast renewable resource is natural plant fibers. The use of the cellulosic fibers as environmentally friendly material in building products contributes to the environmental protection and saves non-renewable resources of raw materials. Wood fibers and recycled cellulose fibers of waste paper appear as suited reinforcing elements for cement-based materials. In this paper, there is used application of Fourier transform infrared spectroscopy (FTIR) on cellulose fibers coming from different sources. FTIR spectra of cellulose fiber samples are investigated and compared with reference sample of cellulose.

Characterization of Manmade and Recycled Cellulosic Fibers for Their Application in Building Materials

The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content(from 47.4 percent up to 82 percent),to compare and to analyze the potential use of the recycled fibers for building application,such as plastering mortar.Changes in the chemical composition,cellulose crystallinity and degree of polymerization of the fibers were found.The recycled fibers of lower quality showed heterogeneity in the fiber sizes(width and length),and they had greater surface roughness in comparison to high purity wood pulp samples.The high purity fibers(cellulose content>80.0 percent)had greater crystallinity and more homogeneous and smooth surfaces than the recycled fibers.The presence of calcite and kaolinite in all of the recycled cellulosic fibers samples was confirmed,whereas only one wood pulp sample contained calcite.The influence of the chemical composition was reflected in the fiber density values.Changes in the chemical composition and cellulose structure of the fibers affected the specific surface area,porosity and thermo physical properties of the fibers.More favorable values of thermal conductivity were reached for the recycled fibers than for the wood pulp samples.Testing the suitability of the recycled fibers with inorganic impurities originating from the paper-making processes for their use as fillers in plastering mortars(0.5 wt.%fiber content of the total weight of the filler and binder)confirmed their application by achieving a compressive strength value of 28 day-cured fiber-cement mortar required by the standard as well as by measured more favorable value of capillary water absorption coefficient.

Low-temperature Synthesis of Belite Cement from Reactive Mixtures Based on Coal Fly Ash

This paper summarizes the selected results of an extensive investigation of application of two methods （hydrothermal and mechanochemical） assisted by calcination for synthesizing belite cement from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of various waste kinds from fluidized brown coal combustion in Slovakian power plant and CaO addition. Based on XRD diffraction patterns and infrared spectra ofpre-treatment products, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment as well as metastables calcium silicates and aluminosilicates in mechanosynthesized products was confirmed. Calcination of hydrothermally treated products led to transformation of CSH phases to wollastonite （CS）, belite and gehlenite phase, whereas creation oft^- and I^-C2S or wollastonite in milled reactive mixture took place. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its mechanochemical or hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.