Study On Property Of Non-steam Curing Ultra-high Performance Concrete

Ultra-High Performance Concrete(UHPC)is a new generation of cement-based composites with good workability,high strength,good toughness and excellent durability.At present,in the production and preparation of ultra-high performance concrete,quartz sand is used as aggregate,and a large amount of active mineral admixture is used,and steam curing or autoclaving curing is used for early curing,which makes it have good mechanics.Performance and durability,but this will increase production costs and increase energy consumption.In this paper,the traditional method is used to prepare ultra-high performance concrete,and quartz sand is used as aggregate.The effects of steam curing and standard curing on the properties of concrete are compared.The results show that the polycarboxylate superplasticizer and high dosage are obtained.When the active mineral admixture is used and the steel fiber content is adjusted to 0.8%,the ultra-high performance concrete slump is 180 mm and the extended diameter is 500mm,the concrete with good working performance can be prepared;steam curing can improve the early strength of concrete,the 3d compressive strength is 128.4MPa and the flexural strength is 14.8MPa,but the strength growth rate is low.The 28d compressive strength is 150.9MPa and the flexural strength is 17.9MPa.Under the standard curing condition,the early strength of concrete is relatively low,and the 3d compressive strength is only 77.8MPa and flexural strength is 12.0MPa,but the strength growth rate is high.The 28d compressive strength reaches 138.4MPa and the flexural strength reaches 15.2MPa.The other mechanical properties and durability of the concrete specimens are excellent under the two curing systems.On the basis of the traditional proportion,natural river sand is used as fine aggregate,and a certain amount of coarse aggregate is added to prepare concrete,which is cured by standard curing.The concrete performance test results show that the increase of the coarse aggregate dosage will reduce the fluidity and flexural strength of the concrete,and will increase the compressive strength and static compressive modulus of the concrete within a certain range.The optimum amount of coarse aggregate is 675kg/m~3.At this time,the concrete slump is 145mm and the extended diameter is 400mm.The working performance is relatively good.Under the standard curing conditions,the compressive strength of concrete is 167.3MPa,and the flexural strength is 12.6MPa,static compression modulus is 52.3GPa,it has excellent mechanical properties;concrete frost resistance and chloride ion penetration resistance meet the requirements of the specification,self-shrinkage strain value is low,volume stability is good.Through the above tests,a non-steam curing ultra-high performance concrete with excellent performance and low cost was finally prepared.