Self-compacting fine-grained concrete for reinforced concrete frame joints filling

Abstract

Self-compacting compositions of fine-grained concrete for filling the joints of the precast-monolithic reinforced concrete frame of multi-storey buildings have been developed. Glenium®51 and Glenium SKY® 505 superplasticizers, and fine-grained river quartz sand with a bulk module of 1.2 were used to prepare the compositions. A part of quartz sand was ground to a specific surface of 100 m2 / kg. The binder was a Portland Cement CEMI 42.5B with a specific surface area of 360 m2 / kg. The spreading of the mixture in the Hagerman cone was 240-270 mm. The self-compacting mixtures compositions containing 1.5% superplasticizers from the mass of cement have an increased fluidity and the ability to freely penetrate holes with a diameter of up to 4 mm. The water-cement ratio when using the superplasticizer Glenium®51 was 0.34, and with Glenium SKY® 505 0.36, respectively. Modified compositions are characterized by low early strength. On the third day of hardening under normal conditions, the strength of the samples was about 30% in comparison with the compressive strength after 28 days. It was found that with moderate heating at a temperature of 30-40 ° C during the first three days, the early strength can be significantly increased. The compressive strength of the self-compacting composition with the Glenium® 51 additive at the content of the ground quartz filler of 15.6% at the age of 28 and 150 days gets strength of 54 and 90 MPa, respectively. The developed compositions of fine-grained concrete with superplasticizer Glenium®SKY 505 have passed the test for the ability to keep steel reinforcement from corrosion. Self-compacting fine-grained concrete with the Glenium®SKY 505 additive is used to fill the joints of reinforced concrete structures of a prefabricated-monolithic frame of a multi-storey building in winter with the use of moderate heating.