Synthesis And Characterization Of Rosin Air-entraining Agent With Hyperbrached Polyamide-ester Structure

Air-entraining agent can improve the working performance and the frost resistance of concrete effectively.These advantages make air-entraining agent widely used in freeze resistance research of concrete overseas.However,there are still some problems of air-entraining agent which sold in the market,such as poor foaming stability,damage the strength of concrete and poor compatibility with other admixtures.These shortcomings limit the application of air-entraining agent in China.Rosin air-entraining agent is a kind of air-entraining agent which is the most studied.The synthesis process of rosin air-entraining agent is simple,the raw materials are abundant and the performance is reliable.However,rosin air-entraining agent also has shortcomings,such as poor foaming stability,damage the strength of concrete and poor compatibility with other admixtures.Hyperbranched polymers is a three-dimensional network structure that has high molecular weight and good stability.Hyperbranched polymers also have a large number of active functional groups at the end which is convenient for modification.In this paper,rosin acid was chemically modified by hyperbranched polymer to synthesize a new air-entraining agent and explore its properties.The main work of the research:1.The synthesis and characterization of hyperbranched polyamide-ester（HPAE）AB₂ monomer was synthesized by reaction between succinic anhydride and diethanolamine at room temperature,and then the second,third and fourth generation hyperbranched polyamide esters were synthesized by reaction of glycerol and AB₂ monomer The synthesis and characterization of hyperbranched rosin air-entraining agents in different proportions.We use a series of methods,such as infrared spectrographic analysis,determination of hydroxyl value and elemental analysis to determining the completeness of molecular structure of hyperbranched polyamide-ester.2.The synthesis and characterization of hyperbranched rosin air-entraining agentsThe rosin acid was modified by different algebraic hyperbranched polyamide-esters,and the hydroxyl-terminated hyperbranched rosin air-entraining agent was obtained by esterification reaction and infrared spectrum,elemental analysis and hydroxyl value test were carried out to determine whether the desired molecular structure was successfully synthesized.Then,carboxyl-terminated hyperbranched rosin of different algebras was obtained by modifying the air-entraining agents with succinic anhydride and the molecular structure was verified by infrared spectroscopy,elemental analysis and carboxyl value determination.3.Performance test of hyperbranched rosin air-entraining agentIn this paper,two kinds of hyperbranched rosin air-entraining agents with different algebras synthesized above are analyzed,including surface tension,foaming performance,foam stabilization performance and bubble liquid film strength.The fluidity of cement paste,slump of concrete,water reducing rate,bleeding rate,setting time and air content were tested.The influence of air entraining agent on the performance of cement and concrete was analyzed.At the same time,it was further determined that the effect of HPAH-G4 and HPAC-G4 is better than G2 and G3.The freeze-thaw resistance and compressive strength of HPAH-G4 and HPAC-G4 were tested,and the optimum dosage was 0.10%-0.16%.Compared with market rosin soap air-entraining agent and triterpene saponin air-entraining agent,it can achieve the same air content,with higher water-reducing rate,slump,cement paste fluidity and longer setting time,lower bleeding rate,better freeze-thaw resistance and compressive strength ratio.HPAH-G4 and HPAC-G4 were compounded with industrial naphthalene series and polycarboxylic acid water reducing agent,which had good compatibility.As a result,the synthesized hyperbranched rosin air-entraining agent can improve the working performance and frost resistance and compressive strength of concrete.It’s can be applied in concrete field wiedly.