| Polycarboxylate superplasticizer is widely used in the concrete construction because of its high water reducing rate,low dosage,slump retention performance,low alkali content,pollution free,etc.In order to abtain good frost resistance and pumpability of pumping antifreeze aid,there will be a high demand for antifreeze components and superplasticizers.Compared to liquid antifreeze pumping admixture based on superplasticizers such as amino,aliphatic series superplasticizer,there is less study on the antifreeze pumping admixture base on polycarboxylate superplasticizer.There is also the same problem about compatibility between cement and polycarboxylate superplasticizer,or polycarboxylate superplasticizer and other components.In this paper,the performance and mechanism of liquid antifreeze pumping base on organic and inorganic ingredient as antifreezing components and polycarboxylate superplasticizer as reducing components was researched,which aimed to improve the problems of Polycarboxylate and cement adaptability,or the liquid antifreeze pumping and concrete adaptability,or the provision of systematic and massive experimental data and basis for the use of concrete in winter projects.Over the world,with respect to the anti-freezing ingredient of salts and organic alcohol,the research of liquid antifreeze pumping aid based on Polycarboxylateand adaptability and anti-freezing ability of cement is very limited,the paper conducted a more systematic study on this,drawing the following conclusions:(1)Either salts or organic components can play a good role in delaying frozen of the liquid freezing pumping aid when stored at negative temperature.The salt test is better,and they are sodium nitrate,calcium nitrate and sodium nitrite,whereas sodium thiosulfate and thiocyanate have poor results;glycerin is the best in organic group,methanol and ethylene glycol are in the second place and triethanolamine is the worst.(2)Thepoly-carboxylic acid superplasticizer with different molecular structure has cement adaptability problems;complex high water reducer,high slump Polycarboxylate 513-521(7: 3)get a good test result of high water reducing rate and a high security collapse effect.(3)The impact of antifreeze component of liquid antifreeze pumping aid and cement adaptability has a regulation: Among salt antifreeze group,calcium nitrate shows the best adaptability with three types of cements and sodium thiosulfate is relatively poor;while in organic antifreeze group,methyl alcohol shows the best adaptability organic antifreeze component and triethanolamine has the worst adaptation of cement;the liquid antifreeze pumping aid formulated by polycarboxylic acid water reducer liquid has less adaptability on Yao Bai cement P·O42.5and Jidong P·O42.5 cement,and greater impact on cement adaptation of Shengwei P·O42.5.(4)The regulation of the impact on liquid antifreeze pumping aid and mechanical properties of concrete by antifreeze component is: good cost performance,the rest antifreeze component can also have good experimental effect;among organic antifreeze component,methanol has the highest cost performance and is the most widely used,glycol and alcohol propionate have good antifreeze effect,but due to high prices,it is rarely used,while triethanolamine is widely used in construction as early strength aid,but its antifreeze effect is not very satisfying.According to the above findings,and taking into account the cost performance,the experiment measure and evaluate the liquid anti-freezing pumping aid with dosage of cementitious material formulated by polycarboxylate superplasticizer of 1.75% from this experiment.It concluded for the performance indicators meet JC475-2004 GB8076-2008 standard regulation indicators. |
