Study On The Sensitivity Of Ether-type Polycarboxylate Superplasticizer

Polycarboxylate superplasticizer(PCE)with their outstanding designability of molecular structure and excellent comprehensive performance is widely used in modern concrete engineering, however, the sensitivity of PEC performance problems have hindered its further development. In view of this,through the net slurry system according to different molecular structure of ether-type PCE performance sensitivity evaluating experiment is designed in this paper. On the basis of the experiment that a certain analysis has been made, and some conclusions are obtained.With oxidation-reduction initiator,four different structure of ether-type PCE were synthesized in aqueous solution,made of HPEG and acrylic acid(AA). Combined the four kinds of products with five brand cement and using the related testing method evaluate the sensitvity to PCE dosage. Sensitivity valuation method was established through testing the thixotropy sensitivity, the structural parameters of PCE were characterized and the sensitivity factor were analyzed. The main work and results were as follows:1. Through the net paste fluidity and bleeding rate of testing, it is proposed on the basis of sustaining slurry stability and new mix slurry exudation rate in one hour as the main reference of PCE " compliance dosage". Comparison test on the slurry viscosity and setting time were performed by adjusting PCE dosage,it was found that the work performance was different when ether-type PCE dosage was changed by the gradual of content to 0.1‰, which was regarded as a certain sensitivity. Fluidity increased with the increase of dosage of PCE, viscosity with the increase of dosage of water reducing agent and had a tendency to increase with the decrease of the first, different delay the hydration of cement that PCE is different, by XRD analysis found that with the increase of dosage delay the 5 h and 24 h of C3 S cement hydration trend increased;2. By the slow stirring(rotates 140 + 5 r/min, the revolution of 62 + 5 r/min),and a quick stir(rotates 505 + 5 r/min, the revolution of 245 + 5 r/min),cement paste of doped with different ether-type PCE shear thinning properties and thixotropy has carried on the comparative study, the sensitivity evaluation of PCE by thixotropic mechanisms problem to discussed, if was not agreed an hour before and after the change trend of thixotropy(larger or smaller, ether-type PCE has certain sensitivity, the stronger the trend of difference, the greater the sensitivity;3. For different ether-type PCE performance in content and shear rate showed the sensitivity of the differences, studied the ether type molecular structure of PCE for the influence of the sensitivity. By GPC characterization testing related structural parameters. Under the suitable main and side chain length,which the greater density of PCE molecule polyoxyethylene in long side chain,was relatively difficult to be cement particle adsorption, showed the relatively poor dispersion, and relatively good dispersion stability.