Modification of cement materials with small doses of hydrothermal nanosilica and plasticizing additives

Abstract

 Experiments were performed on modifying Portland cement materials with plasticizing additives in combination with hydrothermal silicon dioxide nanoparticles using hydrodynamic activation of mixing water. For cement stone and fine-grained concrete, when using the activation of mixing water an effective reduction of the amount of plasticizing additives introduced in the form of a mixture of formaldehyde superplasticizer and fractionated and oxidized lignosulfonate was achieved – up to 0.1% against the total weight of cement instead of 0.2–0.5% without loss of compressive and bending strength. When using hydrothermal nanoparticles of silicon dioxide and fractionated, oxidized and nanomodified lignosulfonate, it is possible to reduce the consumption of polyacrylate hyperplasticizers in 1.5–4.5 times. At the same time, the use of activated water for hydration of cement composites and fine-grained concretes turns out to be an additional factor that increases the strength of solid samples. Small concentrations of a combination of hyperplasticizers with technical lignosulfonates modified by oxidation and / or with hydrothermal silicon dioxide nanoparticles can reduce cement consumption in heavyweight concrete or increase the mechanical strength of concrete to a level corresponding to the concrete class by two units higher, without changing the initial composition of concrete, which is confirmed by tests in concrete’s production conditions.