Changing the Technological Properties and Strength Characteristics of Highly Mobile Concrete by Introducing a Complex Modifier

The article considers the effect of a complex modifier consisting of a superplasticizer and cement crystallohydrates on the properties of cement dough, a highly mobile concrete mixture and heavy concrete obtained by hardening the mixture under normal conditions over a different period of time. As an additive of the superplasticizer, Relamix-PK was studied, administered in an amount of 0.6–0.8 wt. % of cement consumption. The authors investigated finely dispersed hydrated cement as additional crystallization centers. With the introduction of this complex modifier, the delamination of a highly mobile concrete mixture decreases (water separation – by 2 times, water separation – by 3.8 times). There is a significant acceleration of hardening in the initial periods of concrete hardening. Thus, in relation to the additive–free composition, the strength of concrete, which hardened for 1 day under normal conditions, increased 3.5 times, 3 days – 2.5 times, 28 days – 2 times. At the same time, it should be noted that when cement crystallohydrates are added, the hardening process is accelerated more in the initial terms of strength gain. The greatest strengthening effect was obtained by adding a complex modifier consisting of 0.8% plasticizer and 2% hydrated cement.