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Local scale imaging techniques (SEM, CT) and global characterisation tools (X-ray diffraction, TG-DTA, and Fourier Transform Infrared microscope (FTIR)) have been used for years so as to formulate building materials and overcome or understand degradation processes. The objective of this study is to obtain local quantitative information on covalent bonds using a FTIR. Some experimental and theoretical aspects of the chemical mapping are detailed, and illustrated by a study on a model material (hydrated cement, limestone filler and styrene-butyl-acrylate latex). Main experimental setups, post-processing and spectra deconvolution methods are thoroughly discussed. Difficulties arisen from the acquisition technique are illustrated on organic-inorganic material. To enable a reliable quantitative analysis of data, a homemade algorithm is suggested, founded on both statistical considerations (SIMPLISMA algorithm), and iterative penalised resolution (Alternative Least Square). This algorithm implemented on MATLAB leads to a fair spatial distribution of relative concentration for each component of the model cement/latex material. [ABSTRACT FROM AUTHOR]

During the synthesis of geopolymer materials, all of the phenomena and reactions that occur should be included in the analysis of the synthesis. This work aims to study the role that siliceous species play in an activation solution in the presence of pure metakaolin. The formation of a gel phase during the synthesis of a K-geopolymer was shown. Different mixtures were analyzed by infrared spectroscopy. During material consolidation, there is always competition between the geopolymer network and the gel that is governed by a change in the siliceous species. The heat treatment of various gels and solids provided evidence of various networks in geopolymer materials. Finally, the change in the crystallinity of the silica in the activation solution led to a change in the kinetics of the polycondensation reactions, in agreement with previous work. [ABSTRACT FROM AUTHOR]

The activation of metakaolin using an alkaline solution is a method for producing high quality consolidated materials. Si, Al and K are the main factors that influence the nature of the consolidated materials. This study focuses on the effects of the composites on the final network formation. Two types of alkaline solutions, one (S) based on a commercial potassium silicate solution and the other (S) synthesized by mixing KOH and amorphous silica, were studied, and their effects on the network formation of consolidated materials were compared and discussed. Four types of materials were observed and identified based on different Si, Al and K contents, including a geopolymer, gel, sedimented materials and hardening materials. These behaviors are manifested in the various polycondensation mechanisms and microstructures, which were characterized using FTIR spectroscopy, thermal analysis, X-ray diffraction measurements and Scanning electron microscope observations. The influence of Si, Al and K is discussed according to network formation. [ABSTRACT FROM AUTHOR]

The geomaterial foams studied is based on geopolymerization reactions, which is a type of geosynthesis that involves silico-aluminates. Its study during formation has however revealed a different behavior than geopolymer, suggesting the formation of various networks. This work investigates the interaction between initial compounds (metakaolin, silica fume, potassium-based solution) by a kind of mixture decomposition to ultimately understand the formation mechanism of foam. The structural evolution was determined using thermal analysis, FTIR spectroscopy and Al and Si MAS-NMR measurements. The use of different raw materials in combination with various solutions demonstrates the formation of various species in solution. The reactivity of the solution will then evolve in different ways. The Si/K ratio controlled the type of species created and, particularly, the reactivity in the mixture. From the various reactions of dissolution and polycondensation that were deduced, we could identify the composition of the four networks (KSiAlOH; KSiO; KAlSiO,1.5HO; and amorphous silica) constituting the foam. [ABSTRACT FROM AUTHOR]

Porous materials have been prepared from a solution containing sodium silicate and sodium hydroxide with the addition of silica fume. Kaolin and diatomite were also tested as additives to the initial formulation. This method yields consolidated geomaterial foams without requiring thermal treatment above 50°C. The influence of chemical composition on the thermal conductivity was studied. The choice of raw materials was found to play an important role. The accuracy of thermal conductivity measurements was evaluated by comparing the steady state heat flow method with the laser flash technique for five different reference materials giving values within 6%. Using the steady state heat flow method, a value of 0.12± 0.01 Wm-1K-1 was then obtained for consolidated foams, made with kaolin as the precursor, containing approximately 70% of porosity. [ABSTRACT FROM AUTHOR]