Application Of Polycarboxylate In Commodity Concrete

Polycarboxylate is the third generation of High-Performance Concrete water reducer,since the 1980s,developed in Japan,and then a lot of use,to now account for more than 95%superplasticizer.At present,China's Polycarboxylate development time is short,but the pace of development is rapid,complex technology has been greatly improved,so Polycarboxylate from the "aristocratic" to a "civilian".Polycarboxylate superplasticizer is completely different from naphthalene sulfonate formaldehyde condensate(NSF)and melamine sulfonate formaldehyde condensate(MSF)reducing agent,even in very small dosage can make concrete with high fluidity,and also has a low viscosity and slump retention performance at low water-cement ratio.It differs from the cement has a relatively better compatibility,high strength and high fluidity concrete is an indispensable material.Thus,polycarboxylate high performance concrete water reducer has a very important value in the concrete.This article will Polycarboxylate liquor and retarder and air-entraining agent complex study its suitability for cement and concrete frost resistance and mechanical properties,resistance to chloride ion permeability,shrinkage effects.In winter construction and massive concrete pouring in,mixed with antifreeze and expansive complex Polycarboxylate Impact on concrete frost resistance and shrinkage,and applied to practical engineering.Due to construction conditions,research Polycarboxylate secondary mixing effect on the mechanical properties of concrete mixers in the field at the same time explore the feasibility of adding a secondary water reducer.Studies have shown that:Polycarboxylate and sodium gluconate complex and entraining agent,the best dosage of 0.9 to 1.0%,the maximum does not exceed 1.3%,the minimum of not less than 0.7%.Polycarboxylate complex dosage for each additional 0.2%,increasing the fluidity of cement paste around 15mm,10mm or so initial slump of concrete increases.When the sand clay content of less than 3%,Polycarboxylate performance impact is small.When the actual production,C40 and below-strength concrete in the sand clay content should be less than 7%;C50 strength grade concrete and gravel over clay content should not exceed 3%.In winter construction and large volume of concrete pouring,Polycarboxylate be mixed with a certain amount of antifreeze and expanders.Affected by construction conditions,when the concrete pumping difficulties,can be used for mixing concrete admixtures secondary method,dosage is less than 1.0%,after the second adding admixtures,concrete pumping should be finished in 30min at the same time,the second adding water reducer,early strength concrete rising slowly higher late strength.