Abstract
The research is aimed to the clarification of the calcium sulfatedihydrate crystals growth and formation of in the presence of the different polymers based functional additives. The calcium sulfatedihydrate crystals have been synthesized both in the pure form and with the additives. The additives have included a super plasticizer based on a sulfonated melamine-formaldehyde resin (SMF), a methylcellulose (MC) and a redispersible polymer powder based on vinyl acetate, ethylene and vinyl chloride copolymers (VAEVC). The X-ray analysis and the electron microscopy have been applied to identify an influence of the polymer additives over the configuration and size of the calcium sulphate dihydrate crystals. The structural and strength characteristics of the gypsum materials have been also investigated.
Highlights
Nowadays many researchers analyse the influence of the various additives on the hydration hardening process of the inorganic binding materials
The functional additives most widely applied in dry mixtures have been chosen for the research: a super plasticiser on the basis of a sulfonated melamineformaldehyde resin (SMF), a methylcellulose (MC) and a redispersible polymeric powder on the basis of vinylacetic ester, ethylene and vinyl chloride copolymers (VAEVC)
The additives have been entered into the system with a sodium sulfate solution in the following concentrations (% of the mass of CaSO4∙2H2O): sulfonated melamine-formaldehyde resin (SMF) – 1.0; MC – 0.5; VAEVC – 3.0; SMF + VAEVC – 1.0 + 3.0; SMF + MC – 1.0 + 0.5
Summary
Nowadays many researchers analyse the influence of the various additives on the hydration hardening process of the inorganic binding materials. The introduction of sodium sulfide additives leads to the formation of an insoluble calcium sulfide. The last one can serve as a core for the formation of the hierarchical organized structures and promote clogging of pores, strengthening the structure of the anhydrite binder [7]. An addition of the nanomaterials to the Portland cement mortars could potentially enhance their properties as it is shown in [8,9]. The size, morphology and structure of the crystals of calcium sulfatedihydrate, forming in the process of hydration of semi-aqueous gypsum largely determine the properties of the construction materials [10,11,12,13]
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