Additive And Mechanism With The Suppression Of Clay Negative Effects On Polycarboxylate Superplasticizer

Mud in aggregate can reduce the water reducing dispersion of polycarboxylate superplasticizer,clay is a significant component in mud and it have a great negative influence on polycarboxylate superplasticizer. Clays adsorpt polycarboxylate superplasticizer and mixing water is the main reasons that clays can reduce the fluidity of cement paste, mortar and concrete mixed polycarboxylate superplasticizer. Different types of clay have diferent degrees of influnence on polycarboxylate superplasticizer, montmorillonite which have greater adsorption capacity and expansion capacity have bigger negative influence on polycarboxylate superplasticizer.Research currently on the suppression measures of reduce the clay’s adverse effects of polycarboxylate suppression is still in its infancy, there is not a universal solution. Consider "Release the mixing water clay adsorbed ", "select the additives which have great adsorption ability to reduce clay adsorb polycarboxylate superplasticizer " and "prevent clay swelling to reduce adsorb mixing water and polycarboxylate superplasticizer ", select several ceramic water reducer, clay adsorbents and clay anti-swelling agent as additives mixed use with polycarboxylate superplasticizer. In order to provide some ideas about address the negative effects of clay on polycarboxylate superplasticizer, the inhibitory effect of additive have been studied by macro-experiment and the inhibition mechanism of additive have been studied by micro-experiment.The dosage of sodium tripolyphosphate, polyethylene glycol-4000, methylene blue, cetyl trimethyl ammonium bromide and KCl influnenc on the fluidity of cement paste mixed polycarboxylate superplasticizer and clay have been studied. The results showed that sodium tripolyphosphate and methylene blue can not inhibit the negative effect of clay, polyethylene glycol-4000, cetyl trimethyl ammonium bromide and KCl in appropriate dosage range can improve the fluidity of cement paste mixed polycarboxylate superplasticizer, and three kinds of additives exhibited better inhibitory effect on Na-montmorillonite and Ca-montmorillonite than illite and kaolin.According to the test results of cement paste, select polyethylene glycol-4000, cetyl trimethyl ammonium bromide and KCl as additives which have better inhibitory effect on montmorillonite, the dosage of additives influnenc on the fluidity and strength of motar mixed polycarboxylate superplasticizer and montmorillonite have been studied. The results showed that the fluidity of motar mixed polycarboxylate superplasticizer and montmorillonite increased more when polyethylene glycol-4000 and cetyl trimethyl ammonium bromide single-doped than KCl single-doped, polyethylene glycol-4000 and KCl almost no effect on the strength of mortar but cetyl trimethyl ammonium bromide will seriously reduce the strength of mortar. The fluidity of motar can be increased more when three additives complexed than single-doped, but there will still be a significant reduction in mortar strength when cetyl trimethyl ammonium bromide existed. When the content of polyethylene glycol-4000 is 0.3% and the content of KCl is 1.5% complexed, the fluidity of mortar mixed polycarboxylate superplasticizer and montmorillonite could be increased obvious and could not be reduce the strength of motar.The inhibition mechanism of polyethylene glycol-4000, cetyl trimethyl ammonium bromide and KCl have been discussed by TOC test, Zeta potential testing and clay swelling capacity test. The results showed that polyethylene glycol-4000, cetyl trimethyl ammonium bromide and KCl can reduce the amount of adsorption of polycarboxylate superplasticizer on clay, the zeta potential of cement paste mixed clay can be improved and the swelling capacity of Na-montmorillonite and Ca-montmorillonite can be inhibited. Additives can reduce the amount of adsorption of polycarboxylate superplasticizer and water on clays is the main reasons that can increase the work performce of cement paste,mortar and concrete mixed polycarboxylate superplasticizer and clay.