Influences Of Anti-freezing Ingredients On The Performances Of Liquid Anti-freezing Pumping Agents Of Concrete

Under constant dosages, with respect to the liquid anti-freezing punping agents(contains sodium sulfate between 15% and 20%) made with "low concentration" naphthalene-based superplasticizer, the content of inorganic anti-freezing ingredients in liquid anti-freezing pumping agents are limited, in order to prevent the crystallizing precipitate. Under this situation, in order to meet the requirement of anti-freezing performance, organic anti-freezing ingredients often have to be used together with inorganic anti-freezing ingredients in liquid anti-freezing pumping agents, which can decrease the content of inorganic anti-freezing ingredients, so preventing the crystallizing precipitate of liquid anti-freezing pumping agents caused by the saturated solubility decrease of sodium sulfate at low temperature.The researches into the influences of anti-freezing ingredients on the performances of liquid anti-freezing pumping agents have been seldom reported at present, which include the saturated solubility of sodium sulfate at -5°C to +15°C, the crystallizing precipitate of liquid anti-freezing pumping agents at low temperature, the initial flow and flow retention with time of cement paste added with liquid anti-freezing pumping agents and the anti-freezing effects. These performances were investigated in this paper, the conclusions obtained were asfollows:(1) Organic anti-freezing ingredients can improve the saturated solubility of sodium sulfate at -5°C to +15°C, so they are helpful to reduce the crystallizing precipitate of liquid anti-freezing pumping agents manufactured with "low concentration" naphthalene-based superplasticizer at low temperature.The improving effects from high to low is: glycerol, ethanediol,carbinol,diglycol,triethanolamine and ethanol. Inorganic anti-freezing ingredients NaNO₂ , Na₂S₂O₃ and Na₂CO₃ can decrease the saturated solubility of sodium sulfate. So increase the crystallizing precipitate of liquid anti-freezing pumping agents, but the CH₃COONa is helpful to reduce the crystallizing precipitate of liquid anti-freezing pumping agents at low temperature.(2) From the experimental results of cement paste, it was found that ethanediol can improve the compatibility of liquid anti-freezing pumping agents and cement. Carbinol, diglycol and glycerol have little effects, but triethanolamine and ethanol may reduce the compatibility of liquid anti-freezing pumping agents and cement. The influences of inorganic anti-freezing ingredients on the compatibility from high to low is: Na₂CO₃, Na₂S₂O₃, NaNO₂ and CH₃COONa.(3) Glycerol, ethanediol, carbinol, diglycol, triethanolamine and ethanol can improve the anti-freezing effects of liquid anti-freezing pumping agents ,especially ethanediol. Although triethanolamine is an effective organic accelerating admixture, it is not an effective organic anti-freezing admixture. And the anti-freezing effects of inorganic anti-freezing ingredients from high to low is: CH₃COONa, NaNO₂, Na₂S₂O₃, Na₂CO₃.(4) According to above investigated conclusion, also considering performance and price, a type of liquid anti-freezing pumping agent with inorganic-organic anti-freezing ingredients and "low concentration" naphthalene-based and ammonia-based superplasticizers was made. When its dosage is 2.5% of cement in mass, the performance indes of liquid anti-freezing pumping agent can meet the standard JC475-2004 and JC473-2004.Above investigated conclusions provided theoretical basis for manufacturing liquid anti-freezing agents with "low concentration" naphthalene-based superplasticizer in practical application, and have an important guilding significance.