Mortars thermal analysis

In addition to admixtures already described, many others are used to produce special modification of concrete and mortar. Thermal Analysis Techniques have not been applied significantly to examine the role of these admixtures in concrete, although they have potential. A thorough treatment of these admixtures is presented in Ref 89. A brief description of some of these admixtures follows. 

Polycrystalllne samples of LaSrAlCu05 were prepared by solid state reaction of Aldrich cupric oxide (99.999%), strontium carbonate (99.999%), lanthanum oxide (99.999%) and aluminum nitrate (99.999%). Powders were ground with a mortar and pestle and calcined In air at 950 C for 5 days with dally grindings. The product was dark black. Thermogravlmetrlc studies with a Du Pont Thermal Analysis System by reduction In hydrogen were used to determine the oxygen composition. 

In this framework, in the specially designed mortars consisting of binders of either lime and metakaolin or natural hydraulic lime and fine aggregates of carbonate nature, nano-titania of anatase (90 per cent) and rutile (10 per cent) form has been added (4.5-6% w/w of binder). The aim was to study the effect of nano-titania in the hydration and carbonation of the above binders and to compare the physico-chemical properties of the nano-titania mortars with those mortars without nano-titania, used as reference. Thermal analysis (DTA-TG), infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to investigate the evolution of carbonation, hydration and hydraulic compound formation during a six-month curing period. Furthermore, the stone-mortar interfaces, the adhesion resistance to external mechanical stress, relative to the physicochemical characteristics of the stone-mortar system and the role of the nano-titania as additive, were reported and are discussed in this chapter. 

Moreover, thermogravimetric analysis and differential thermal analysis (DT-TGA) has been carried out to obtain a complementary knowledge about the binder composition and purity. The figure 6 illustrates representative thermograms obtained for studied samples. The thermograms of all samples are typical of aerial lime mortars of carbonate nature with a typical weight loss at temperatures ranging from 600 to 750 °C (Bakolas et al., 1998 Marques et al., 2006 Adriano et al., 2009). 

Fig. 6. Thermal analysis curves of mortar and different binder fractions of SNR-108 sample.

Since mercury porosimetry has been used to a considerable extent in the study of hardened Portland cement, it seemed appropriate to apply it in the assessment of porosity of Ancient Egyptian Mortars. X-ray diffraction and simultaneous thermograviraetry and differential thermal analysis were used as additional techniques in the present study. 

Although not specifically delineated, the volume is also divided into three general sections. The first addresses the full spectrum of infrared detectors and contains a limited coverage of all the material presented in subsequent chapters. It serves as an introduction to the volume and presents to the reader an overall view of the present state of the infrared technology art. It also serves as the mortar between the more in-depth discussions which follow. The midsection. Chapters 3,4, and 5, is a detailed analysis of those detector types which are most widely used today thermal, photoconductive/photovoltaic and photoemissive. 

Until the mid-1970s, all efforts to the study of masonry structures in fire conditions were conducted individually. The influence of thermal action in the analysis of the pieces or the mortar or experimental studies on large masonry structiural elements has been performed by a few researchers worldwide. After meetings of the GIB 23A Bearing Walls Commission in Athens in September 1978 and later with the Building Research Establishment (BRE), the B CERAM RA was commissioned to prepare a technical document on the fire behavior of masonry structures (requested by the Fire Research Station). This document had to include ... 

Multiphase mixture formation between a binder (lime and/or cement) with aggregates smaller than 0.5 mm after a hydration process, and isotropic behavior mortar make a non-crystalline element with irregular crystalline configuration. In these solids, the calculation of thermal/mechanical properties is more complex since it is necessary to consider for analysis related to this non-periodic ordering several factors. 

Thermal analytical techniques have been applied to investigate the causes leading to the deterioration of concrete subjected to various environmental factors. A mortar nearly two thousand years old obtained from El Tajan near Mexico City was analyzed by TG and electron microscopy. TG analysis was done on samples taken from different areas and depths. The loss of water below 100°Cwas caused by the adsorbed water from the volcanic tuff, while the endothermal effect at >700°C corresponded to the carbonated lime and carbonated silicates and aluminates derived from the pozzolan. The extent of the reaction of lime with pozzolan was computed to be 6.91%. 

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