Nauka i Tehnika (Dec 2015)
RAPID TEST METHOD FOR EVALUATION OF ANTIFREEZE ADDITIVE EFFICIENCY
Abstract
Usage of chemical additives while executing concrete works at negative temperatures is considered as a convenient and economical method. Range of the used antifreeze additives is rather wide. A great number of new additives are advertised but their characteristics have not been practically studied. Evaluation of the antifreeze additive efficiency is unfortunately rather long process and it does not provide comprehensive data on concrete structure formation processes. Due to this development of rapid and comprehensive methodology for construction companies is urgently required.Freezing processes of antifreeze additive aqueous solutions and hardening of cement paste with them have been investigated in the paper. The paper proposes a methodology for determination of freezing point for aqueous solutions of chemical additives of various applications. Identity of freezing point for a chemical additive aqueous solution and cement paste with an equal concentration of the additive in the paste pore fluid has been determined while taking calcium nitrate and sodium formate additives as an example. The paper demonstrates the possibility to evaluate efficiency of antifreeze additive action on the basis of kinetics in temperature changes of the cement paste with additives by its consecutive freezing and defrosting. A methodology for operational evaluation in the field of chemical additive application for concreting items at negative temperatures has been offered in the paper. The methodology does not require deficient and expensive test-equipment. It can be applied at ordinary construction companies and it is comprehensible for personnel of low-qualification. The paper shows the possibility to develop an original methodology for designing concrete structure which is based on operating efficiency determinations for single and integrated antifreeze additives.
