Performance Characteristics of Slag-Alkali Decorative Cements and Mortar

Abstract

The use of slag-alkaline cements as decorative cements is quite promising. When using bleaching additives TiO2, kaolin and CaCO3, white cements with a degree of whiteness of 70...94%were obtained. But in addition to decorative properties, such cements and materials based on them are subject to requirements to ensure the necessary technological and operational properties.The article discusses the main operational properties of decorative slag-alkaline concrete mortars - long-term strength, water-holding capa-city of mixtures, resistance to fflorescence, resistance to steaming and exposure to atmospheric factors(frost resistance, weather resistance, color stability).It has been established that white slag-alkali cements at the age of 28 days have a compressive strength of 49...56,8 MPa. All compositions of white cements have good hardening dynamics and, based on the strength at the age of 2 days 35...37 MPa, they can be classified as fast hardening. It hasbeen established that in the long term (3 months ormore) the strength of slag-alkaline decorative cements practically does not differ from the control compositions and amounts to 66,5...67,5 MPa.All compositions of slag-alkaline decorative solutions demonstrate high frost resistance. It has been established that the loss of their strength after 150 cycles of freezing and thawing (which corresponds to the F200 brand) is only 1,73...3,87%, there are no weight losses, no surface peeling is observed. All samples of slag-alkaline decorative mortars containing bleaching additives successfully passed the weather resistance test. Their strength loss after 100 cycles of soaking and drying amounted to 6,5...9,2% with an allowable 25%.The high color fastness of slag-alkali decorative pigmented cements to the effects of ultraviolet radiation and steaming has been established. Color as a result of exposure to ultraviolet irradiation and thermal treatment has not changed. In addition to industrial mineral pigments, red mud, which is awaste product of alumina production, has been successfully used as a pigment.In the course of the work, the tendency of decorative slag-alkaline solutions to efflorescence was studied. The introduction of 0,25...0,5% sodium carboxymethylcellulose additive completely eliminates their appearance, improves the water-retaining capacity of solutions and their plasticity.