The Influence of Complex Additive on Strength and Proper Deformations of Alkali-Activated Slag Cements

Abstract

The peculiarity of alkali-activated slag cements (further, AASC’s) is increased proper deformations, which can cause increased cracking and reduced durability of structure. The paper is devoted to manage AASC’s proper deformations. The main task was to determine the composition of complex additives (further, CA’s) in system «ordinary portland cement (further, OPC) clinker - mineral compound of different anionic type - surfactant» in presence of sodium metasilicate (further, MS) to affect on hydrated AASC performance while ensuring effective structure of artificial stone by criterion of shrinkage deformations. Comparative analysis of hydrated cement systems "OPC clinker - MS", "OPC clinker - mineral compound - MS" and "OPC clinker - mineral compound - MS - surfactant" showed that the greatest effect on reduction of proper deformations occurs when the mineral compounds relate to electrolytes, i.e. Na2SO4 and NaNO3. Hydrated system is characterized by expansion (+0,062 mm/m) in presence of Na2SO4. Almost no shrinkage is supplied by application of NaNO3 (-0,062 mm/m). The obtained CA’s were tested in AASC. CA in the system “OPC clinker - NaNO3 - surfactant” provides the initial setting 43 min, the end - 65 min with accelerated strength. Investigated AASC can be classified as non-shrinking cement. This phenomena is ensured by increasing density, homogeneity and monolithicity of hydrosilicate formations, as well as due to formation of hydroaluminosilicate structures with different morphology by inclusion of nitrate anions.

Design of slag cement, activated by Na (K) salts of strong acids, for concrete reinforced with steel fittings

“…Studies [44,45] note that the issue related to low cement strength is associated with a low Ca/Si ratio in the specified phases. The expediency of an additional calcium activation of slag in the composition of the alkaline-activated SC was confirmed as a way to improve strength when using the additives of lime [46] or the Portland cement [34].…”

“…As regards the environmental aspect, replacing part of the clinker in cement composition with mineral additives contributes to reduc-prerequisite to use BP to activate GBFS in cement composition. In addition, there is a known benefit associated with the reduction of shrinkage deformations of SC when using, in addition to the alkaline activator, both BP [33] and SSA, which are the predominant ingredients of BP [34].…”

Development of nanomodified rapid hardening clinker-efficient concretes based on composite Portland cements

“…At the same time, due to the pozzolanic activity, amount of low-basicity calcium hydrosilicates C-S-H (I) grows and hydrogelenite belonging to AF m phases is also formed. This approach to improving efficiency of alkaliactivated cements and concretes was used in [22,23].…”

Properties of Concretes Incorporating Recycling Waste and Corrosion Susceptibility of Reinforcing Steel Bars

“…Ground granulated blast furnace slag has begun to be used widely since the discovery of its latent hydraulic properties. Many researchers have been conducting lots of experiments to determine the properties of cements and concretes containing GGBFS and fly ash [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. According to Ivashchyshyn et al [ 15 ] and Kurdowski [ 22 ], properties of cements and concretes containing blast-furnace slag depend on the chemical composition, fineness of slag, and the amount of vitreous structure in slag.…”