The dissertation is devoted to the development of theoretical bases for obtaining alkali-activated composite Portland cements with high early strength and nanomodified rapid hardening concretes with improved quality parameters. There were substantiated the principles of composite construction of technologically optimized, microstructurally-engineered multimodal Portland cements with high early strength, taking into account the peculiarities of the substance and particle size compositions, the influence of physical factors (pozzolanic activity, water demand, bleeding etc.) on the complex properties of the cementitious systems (workability, early and standard strength, durability, cost, environmental impact). It was shown that technological optimization due to the combination of mineral additives (GGBFS, superzeolite and limestone) with different surface energy (Kisa are 7,85; 9,71 and 11,52 μm-1.vol.%) provides microstructurally-designed multimodal composite Portland cement with high early strength of type CEM II/ B-M (S-P-L) 42,5R–LH, characterized by uniformity and stability without separation and delamination.
It has been proved, the effectiveness of complex influence of alkali metal salts and polycarboxylate type superplasticizer on the processes of early structure formation of Portland composite cement. It was shown that the replacement of 1,0-1,5 wt.% SO3 from gypsum dihydrate in the CEM II/B-M composition with more soluble sodium sulfate in the amount of 1,77-2,65 wt.% opens the way to increase the efficiency of alkaline sulfate activation. The improved characteristics of the modified alkali-sulfate activated cement stone are ensured by the formation of zeolitic alkaline hydroalumosilicates, nanodispersed C-S-H(I) phases and ettringite. There were established the principles of nanomodification of cement stone on micro- and nano-scale levels and by the method of sol-gel technology was synthesis alkaline nanocomposite N-C-S-H-PCE. Alkaline nanocomposite is shown to be nanodispersed alkaline calcium hydrosilicates with high surface activity (Kisa=45 μm-1.vol.%), which provides directional control of structure formation processes in the R2O-CaO-Al2O3-SiO2-H2O system and determines (from nano- to micro- and macrolevels) the technical properties and long-term performance characteristics of cementitious matrix.
Alkali-activated Portland composite cement with high early strength has been developed with taking into account the nanotechnological approach. It is shown that the combination of physical and chemical approaches by using alkaline activator, polycarboxylate superplasticizer, nanosilica and alkaline nanocomposite creates the possibility of obtaining super rapid hardening high-strength Portland composite cements ACEM II/B-M (S-P-L) 52,5R (CF = 0,65; Rc1/Rc28 = 44,9%; Rc2/Rc28 = 96,2%, Rc28 = 68,2 MPa), rapid hardening clinker-effective composite cement CEM V/A 42,5R (CF=0,50; Rc2/Rc28=51,5%; Rc28=61,2 MPa); ultra high performance heat and corrosion resistant pozzolanic cement CEM IV/A (P) 52,5R-SR (CF =0,78; Rc1/Rc28 = 61,9%; Rc2/Rc28 = 90,1%, Rc28=97,2 MPa); decorative composite cements.
Nanomodified rapid hardening clinker-efficient concretes have been developed, characterized by improved technological, technical and performance properties - S4 consistency class, rapid hardening (fcm2/fcm28 = 0,51-0,58), high strength classes C50/60, C60/75), high water resistance (W14 - W18), frost resistance (F300 - F400). The modulus of elasticity of nanomodified concrete increases to 49.6 GJ, the fracture toughness increases to Ki = 0,90 MPa·m1/2. It was shown that the introduction of complex nanomodifiers (liquid alkaline nanocomposites N-C-S-H-PCE) allows to obtain nanoengineered composites (flexural/compressive strength - 15/160 MPa, abrasion – 0,02…0,04 g/cm2) for using as a lining material in conditions of extreme abrasive wear at temperatures up to 400oC (cement industry, etc.). The industrial implementation has been carried out and the technical and economic efficiency of the use of alkali-activated Portland composite cement with high early strength and nanomodified concretes based on them has been determined.
