The Influence Of Polycarboxylate Superplasticizer To Hydraulic Compound Concrete Durability Research

The major influencing factor determining the service life of the dam is the frost resistance of concrete dam in the cold area.In order to increase the frost resistance of concrete dam in this area,one of the main measures is to add the air-entraining admixtureand water-reducing admixture.Take the design of concrete mixture ratio in spillway of Nierji water conservancy project as the background,adding polycarboxylate superplasticizer and a large proportion of fly ash and ganguepowder in concrete can be synthesized into the concrete dam with high frost resistance,carbonation resistance,low hydration heat and good economical efficiency.Through the experiment,adding 0.6%,0.8%,1% and 1.2% of polycarboxylate superplasticizer in the ordinary cement mortar and C20 concrete,from which we can analyzethe influence of cement mortar and the physical and mechanical properties of concrete.The test results indicate that after adding the poly-carboxylic acid,the ability of concrete slump retaining was better and the compressive strength has increased.The highest compressive strength was at 1%,reaching 49.1Mpa.Atthe condition of 1% poly carboxylic acid,each 20%,30% and 40% single fly ash,and with 8:2 and 6:4 of compound fly ash and slag powder were prepared into nine sets of 27 C20 concrete specimens.Test results show that no matter the strengths of single or compound concrete specimens could satisfy the design requirement,but in the case of compound fly ash,with the increases of slag powder ratio and the concrete strength,the maximum strength could be increased by 15%.Under the circumstances of adding 1% of poly carboxylic acid water reducing agent,we studied the effects of carbonization depth,hydration heat release,frost resistance and etc.durability of C20 concrete,regarding to three cases of adding 40 % fly ash,32% fly ash and 8% slag powder,and 24% fly ash and 16% slag powder respectively.Adding 24% fly ash and 16% slag powder is the best comprehensive effect trial of these three.At the end,taking mix proportion of hydropower spillway in Nierji as the comparison,we carried out an orthogonal experiment of three factors including cement dosage,water consumption and sand ratio,from which the mix proportion design parameter of polycarboxylic acid C20 concrete were optimized.Comparing themix proportion of hydropower spillway in Nierji,the mix of polycarboxylate superplasticizer,fly ash and slag powder can save 41.7% of the cement dosage and 17.3% of the cost of concrete.