A NEW SPECIAL CLINKER COMPOSITION WITH LOW CLINKERABILITY TEMPERATURE THAT PRODUCES A CEMENT HAVING HIGH RESISTANCE TO STRONGLY AGGRESSIVE SULFATE ATTACK

摘要

Certain naturally occurring cements, having constant raw composition, have been found to possess raw properties with low clinkerability temperature. These provide cement that possesses a much higher resistance to the attack of strongly aggressive sulfate solutions. The resistance to sulfate attack was determined by means of series of 20 x 20 x 20 micro-cubes, and series of prisms 40 x 40 x 160 mm, in accordance with the 196-1 EN standard, of pure paste with a water/cement ratio of 0.4, which were similarly cured in water at 20°C. The physical and chemical parameters were determined for the prepared mortars compressive strength, the results of which are provided. A study of the modification of the internal porosity of the samples in function of the sulfate ions was carried out. The results and conclusions appear to provide a new aspect to the influence of structure density of the C-S-H phases in expansion due to ettringite formation, when the silicate content is low and there is also sufficient space for occupation by the ettringite. The need to locate clinkers having a low degree of clinkerability temperature for sustainable energetic and ecological reasons and to obtain information that leads to better understanding of the effects of expansion due to sulfates justify the interest in this work. A new parameter is suggested both for the control of concrete sensitivity to sulphate attack as well as in the verification of actual behaviour in field studies.