Mechanoactivation of Portland cement in the technology of manufacturing the self­compacting concrete

• Main Authors: Ivan Barabash, Darya Harashchenko
• Format: Article
• Language: English
• Published: PC Technology Center 2018-06-01
• Series: Eastern-European Journal of Enterprise Technologies
• Subjects: mechanoactivation; self-compacting concrete; effective viscosity; superplasticizer; polycarboxylate; microsilica; polypropylene fibers
• Online Access: http://journals.uran.ua/eejet/article/view/133235

This paper examines the intensive separation technology for producing a self-compacting concrete (SCC). We substantiate the proposed technology of SCC production through the effective control over viscosity of cement-water compositions, which to a large extent ensure the mobility of concrete mixes. A separate preparation of cement-water compositions at a high-speed mixer with its subsequent mixing with fillers in a regular concrete mixer profoundly changes the priorities in the production technology of a concrete mix. We substantiate the idea on that the use of the separation technology could optimize the modes of high-speed mixing in order to separately prepare the highly concentrated cement-containing suspensions under conditions of intensive hydrodynamic impacts on them. Particular attention is paid to studying the effect of content of the superplasticizer of polycarboxylate type Relaxol-Super PC, microsilica, and polypropylene fibers, on effective viscosity of the cement-containing suspension. Comparative analysis of influence of the original formulation factors on its value is described. It was found that the mechanoactivation of a cement-containing suspension in the presence of the admixture Relaxol-Super PC leads to the complete destruction of its original structure, which is necessary for the uniform distribution of microsilica and polypropylene fibers in the volume. We describe the features of grain composition, rendering exclusive fluidity to the concrete mix, as well as the possibility of laying it in the mold without vibration. The intensive separation technology makes it possible to obtain SCC with the F4, F5 grades for fluidity, and compressive strength at the age of 28 days not less than 55 MPa. We have scientifically substantiated and experimentally confirmed the effectiveness of mechanical activation for the separation technology of self-compacting concrete mixes and the high-strength concretes based on them.