JPKic 结构热计原黑 §1.2 Concrete Concrete is formed from hardened mixture of cement,water, land,crushed stone or gravel easy construction Main indices for (High strength) Concrete evaluating concrete requirements Durability quality Cost effective
§1.2 Concrete Concrete is formed from hardened mixture of cement, water, land, crushed stone or gravel Concrete requirements easy construction (High strength) Durability Cost effective Main indices for evaluating concrete quality
JPKIC 结构设计原理 Teprincipledistctiredesign 1,Strength of concrete Three strength indicators fuff Factors:The size and shape of the materials,the nature of the material,concrete mixture,curing environment, construction method,the shape and size of specimens,test methods,loading conditions and mechanical properties of specimens
1、Strength of concrete ⚫ Three strength indicators ： cu f c f t f ⚫ Factors:The size and shape of the materials, the nature of the material, concrete mixture, curing environment, construction method, the shape and size of specimens, test methods, loading conditions and mechanical properties of specimens
JPKIC 德构热试原得 The Cubic Compressive Strengthf (1)Definition:In GB50010-2002,the grade of concrete is rated by the compressive strength of a cubic specimen with side length of 150 mm,cured for 28 days under standard curing conditions(temperature isat20℃±2℃，humidity is over95%o),tested by standard test method
The Cubic Compressive Strength （1）Definition: In GB50010-2002,the grade of concrete is rated by the compressive strength of a cubic specimen with side length of 150 mm, cured for 28 days under standard curing conditions(temperature is at 20℃±2℃,humidity is over 95%), tested by standard test method cu f
JPKIC (2)Factors 结构计原黑 Sample Strength discount size factor just for cubic Sample size strength 150×150×150 1.0 (Size effect) 200×200×200 1.05 100×100×100 0.95 Direct compression(Standard test methods Test MethodIndirect compression(Between test block and the bearing plate coated with grease or filled with plastic sheets A faster load will have a higher strength grade
（2） Factors Sample size (Size effect) Direct compression (Standard test methods ) Indirect compression (Between test block and the bearing plate coated with grease or filled with plastic sheets ) Test Method A faster load will have a higher strength grade 试件尺寸 强度折减系数 （关于立方体强度） 150×150×150 1.0 200×200×200 1.05 100×100×100 0.95 Sample size Strength discount factor just for cubic strength
JPKIC (3)Requirements on the concrete strength grade 箱构计原黑 "Bridge Specifications"provides:for the load-bearing part of the concrete. Highway bridge strength grade is divided into C20~C80,5 Mpa is an incremental.The following ordinary strength concrete C50,C50 and above for high-strength concrete. Common grades:C15,C20,C25,C30,C35,C40,,C45,C50,C55,C60 C65,C70,C80 RC members should not be less than the C20,when using HRB400, KL400-class steel reinforcement should not be less than the C25 Prestressed concrete members should not be less than the C40 Note that C40 means that the standard value of 40MPa cube strength of concrete strength grade
（3）Requirements on the concrete strength grade • “Bridge Specifications“ provides: for the load-bearing part of the concrete. Highway bridge strength grade is divided into C20 ~ C80, 5 Mpa is an incremental. The following ordinary strength concrete C50, C50 and above for high-strength concrete. • Common grades: C15, C20, C25, C30, C35, C40,, C45, C50, C55, C60, C65, C70, C80 • RC members should not be less than the C20, when using HRB400, KL400-class steel reinforcement should not be less than the C25 • Prestressed concrete members should not be less than the C40 • Note that C40 means that the standard value of 40MPa cube strength of concrete strength grade