Synthesis And Application Of Polycarboxylic Acid Water Reducer

Polycarboxylic acid water reducer is the third generation water reducer.It has the advantages of low dosage,high water reducing rate,high slump retention,high dispersion and no pollution in production.Polycarboxylic acid water reducer has been widely used in ready-mixed concrete,but due to the impact of raw material changes and cost,there are still some problems to be solved in practical application.This paper mainly studies the problems encountered by polycarboxylic acid water reducer in low-grade concrete and the application of high-performance concrete in the actual production process,and puts forward some feasible solutions with practical engineering as an example.1.Polycarboxylic acid superplasticizer modified by sodium lignosulfonate was synthesized by self-made catalytic initiation system with 5%substitution degree of polyether Macromer and 4%acid-ether ratio.Compared with the unmodified polycarboxylic acid water reducer,the water reducing performance of the water reducer is basically unchanged,the plasticity retention performance is improved,and the cost of mother liquor is reduced by 196yuan per ton.Compared with naphthalene superplasticizer,sodium lignosulfonate modified polycarboxylate superplasticizer(C30)uses 170kg of water,220mm of initial slump,490 mm of expansion,175kg of water,210 mm of slump and 480 mm of expansion.The slump and expansion of polycarboxylic superplasticizer are better than those of concrete mixing with naphthalene superplasticizer under the condition of low water consumption.The concrete produced by the polycarboxylic acid water reducer has better economy and workability.2.The mud content of sand has a great influence on polycarboxylic Water reducer.When the content of polycarboxylic acid water reducer is 2%and the mud content of sand is 5%,the water reducing rate is 6.45%higher than that of polycarboxylic acid water reducer,and the strength of test block is 4.14MPa higher.The influence of mud content of sand on concrete can be reduced by increasing the content of polycarboxylic acid water reducer.Compared with other admixtures such as naphthalene water reducer and aliphatic group,the concrete made of polycarboxylic acid water reducer has about 3MPa higher 28days strength than the concrete made of other two admixtures when using the same cement.3.According to the requirement of C70 self-compacting concrete in Shenyang Shengjing Financial Plaza Project,poly carboxylic acid water reducer with three functions of reducing viscosity,retaining slump and retaining water was developed.Through the combination of three kinds of functional water reducer and common poly carboxylic acid water reducer,the technical indexes of concrete prepared are:T500slump inversion time is 5s,concrete expansion is 670mm,V-shaped funnel flow.After 10seconds,the height difference between two sides of U-tube test is 15mm,the anti-segregation rate is 8%,and the height difference between inside and outside of J-ring is 10mm.At the same time,the durability and strength of high performance self-compacting concrete meet the engineering requirements.