Research On Synthesis And Performance Of Polycarboxylate Superplasticizer With Slump Loss Resistance

Polycarboxylate superplasticizer as a new type of high performance water reducer, become the research focus in the concrete additive industries, which has low dosage, higher water reducing rate, better spread performance, smaller slump loss, environmental protection and other characteristics. The paper introduces the history and status quo of water reducing agent in the concrete admixture, and discusses mechanism of polycarboxylate super-plasticizer in detail. Combined with the polymer slump loss mechanism, polycarboxylate superplasticizer with slump loss resistance was designed.According to the principle of molecular design, mixed the small function monomers of malefic anhydride (MA) and acrylamide (AM) with allyl polyethenoxy ether (APEG) or prenyl polyoxyethylene ether (TPEG), two different kinds of polycarboxylate superplasticizer(BT-1,BT-2) was resp-actively polymerized in water solution, which contained functional groups of carboxyl(-COOH), amides base (CONH2-), poly vinyl ether oxidation group [(OCH2CH2)n-].Through the discussion of factors of polymerization, the best technical parameters synthesizing water reducing agents was obtained:the best molar ratios synthesizing BT-1,BT-2are respectively n(APEG):n(MA):n(AM)=1:1.8:1.2and n(TPEG):n(AM):n(MA)=1:1.6:1.9; the dosage of initiator is3.5%～4% of the total weight of monomers; The reaction concentration is40%; The reaction temperature is75℃; Active monomer(AM) solution and initiator solution dropwise add respectively, and active AM solution drops out before the initiator solution0.5h.Using aqueous gel chromatography, infrared spectroscopy and other detection methods, the corresponding structure characterization for polycarboxylate superplasticizer with slump loss resistance were charact-erized. Meanwhile, the paper makes lots experiments, such as the cement adsorption quantity, different cement mortar compatibility, water-reducing rate, compressive strength and concrete slump and so forth, to make clear to various performance indicators of the homemade water reducing agents. The results show that they comply with relevant standards, and have good effect of slump loss resistance the slump in the practical application.