Contact strength of mechanoactivated fine concretes from granulated blast-furnace slags
Authors: V. I. Bolshakov, М. O. Yelisieieva, S. А. Shcherbak
Number of views: 283
Purpose. Strengthening of fine concrete contact zone by mechanical processing of all components of the concrete mix in a mixer-activator and aggregate application with rough surface. Methodology. Rotary activator PC-06, developed by Scientific and Research Institute of Construction Technology, was used as a mixer-activator to achieve this purpose. Granulated blast furnace slag, having a more developed rough surface than sand, was used as fine aggregate. This apparatus provides intensive homogeneous mixing of concrete mix components, processing of raw materials (purification of their particles from contaminants), and mechanical destruction of granulated blast furnace slag surface layers and other components of the mix. Findings. During the preparation work, experimental research of new formations composition of fine concretes, using differential thermal and x-ray phase analysis methods, and physical-mechanical properties of fine concretes in accordance with the applicable standards of Ukraine, were carried out. It is established that the phase composition of new formations of fine concretes made from activated and non-activated mixes, is not changed. Their main difference is the size of generated effects and temperature intervals of occurrence of these peaks. Thus, in fine concretes made on the basis of the activated mixes, magnitude of effects is less, indicating a higher hydration degree of its components. Besides, TG curves of concrete specimens show that weight loss of gel calcium hydrosilicate of concrete from a mechanically activated mix is 0.5...0.7 % more than of concrete from a non-activated mix, which indicates a larger number of these formations in concrete from activated mixes. In general, concretes of different composition, made from a mix, processed in the mixer-activator, have higher mechanical strength. Originality. Ideas about the influence of mechanical activation of components of fine concrete mixes with forming humidity in a rotary mixer-activator on the value of the contact strength of cement and aggregates got further development. Practical value. Strengthening of contact area of fine concrete in the exercise of the combined machining of all concrete mix components in the mixer-activator is achieved owing to increment of hydration degree of raw concrete components; creation of conditions for solid-phase chemical reactions between its components; structure improvement of the received material. It promotes significant increase of mechanical strength of mechanoactivated fine concretes (around 5 times) in comparison with concretes, made from a non-activated mix, which makes it possible to decrease the cement consumption when manufacturing 1 m3 of concrete up to 59 %.