INFLUENCE OF QUARTZ FLOUR ON TECHNOLOGICAL PROPERTIES OF SELF-COMPLETED CONCRETE MIXTURES

Subject: technological properties of self-compensating concrete mixtures with a fine-grained microfiller, represented by quartz flour. Objectives: to determine the quantitative parameters of the influence of the granulometric composition of quartz flour and its dosages on the workability and delamination of self-compacting concrete mixtures with a constant consumption of gauged water and various contents of the superplasticizing additive. Materials and methods: portland cement CЕМ II/A-S 42,5N was used in the work; natural pit sand of 0…5 mm fraction; crushed stone of fraction 5...20 mm; Silverbond quartz flour with an average particle size of 17 μm and 34 μm (grades 15 and 30, respectively); Superplasticizer based on polycarboxylate ester GLENIUM®115. The grain size composition of microfillers was investigated by laser diffractometry using the laser particle analyzer "Analysette 22" COMPACT in accordance with ISO 13320-1: 2009. The mobility of the cone flow diameter and the delamination of the concrete mixture were measured in accordance with GOST 10181. Results: it was researched the influence of quartz flour of various granulometric composition (with an average particle size of 17 μm and 34 μm), applied in dosages of 50, 100 and 150 kg/m3, on the technological properties of self-compacting concrete mixtures with different superplasticizer content (2, 4, 6 and 8 l/m3) and a constant flow of gauged water, as a result of which it has been established that the use of quartz flour of finer grinding provides higher values of SCC mobility under the condition of equal content of superplasticer and gauged water; when using a more coarse quartz flour, the growth of the dosage of the superplasticizer causes a more pronounced increase in the mobility of the concrete mixture; increasing the dosage of quartz flour allows to reduce the delamination of SCC. Conclusions: experimental studies have shown the effectiveness of the use of quartz flour for obtaining SCCs of various classes of workability (SF1 ... SF3) and resistance to delamination (SR1, SR2) and have established that the use of quartz flour D50 = 34 μm leads to insufficient optimization of the granulometric of the composition of the SCC and, as a consequence, stratification of the mixture with its low mobility, whereas the thinner fraction D50 = 17 μm, of the same type of microfiller, makes it possible to obtain resistant to the delamination of any SCC in for the workability due to varying dosages of both the microfiller and superplasticizer.