高温蒸汽养护复掺混凝土力学性能时变特性与模型研究

Time-Varying Characteristics and Models of Mechanical Properties of High-Temperature Steam Curing Multi-Mixed Concrete

为研究高温蒸汽养护下粉煤灰-矿粉机制砂混凝土(简称复掺混凝土)力学性能时变特性与模型,本文结合某高速公路高温蒸汽养护复掺混凝土预制梁项目,设计了蒸汽-标准养护、蒸汽-自然养护和标准养护三种养护方式,测试了不同阶段复掺混凝土的抗压强度、劈裂抗拉强度和弹性模量,探究了抗压强度与劈裂抗拉强度、弹性模量的关系。结果表明:合适的蒸汽养护方式能促进复掺混凝土抗压强度、劈裂抗拉强度和弹性模量更快增长,其中对抗压强度形成作用最显著,后期的力学性能不倒缩;蒸汽养护恒温阶段复掺混凝土的力学性能具有最大的增长率,其次是升温阶段,降温阶段力学性能增长率最小;蒸汽-标准养护方式下复掺混凝土的抗压强度时变模型可取对数或对数与幂函数复合函数,劈裂抗拉强度、弹性模量时变模型可取幂函数。

To study the time-varying characteristics and models of mechanical properties of mechanism sand concrete mixed with the fly ash and the slag(referred to as multi-mixed concrete)under high-temperature steam curing,combined with a high-temperature steam curing multi-mixed concrete precast beams of a highway project,steam curing-standard curing,steam curing-natural curing and standard curing modes were designed to test compressive strength,splitting tensile strength and elastic modulus of multi-mixed concrete at different periods.The relationship between compressive strength and splitting tensile strength,elastic modulus were explored.The results show that a suitable steam curing method can accelerate the growth of compressive strength,splitting tensile strength and elastic modulus of multi-mixed concrete,with the most significant effect on the development of compressive strength,and the mechanical properties don’t retract in the later stage.During the constant temperature stage of steam curing,the mechanical properties of concrete have the highest growth rate,followed by the heating stage,and the mechanical properties have the lowest growth rate during the cooling stage.Under steam-standard curing mode,time-varying model of compressive strength of multi-mixed concrete can take logarithm or logarithm and power function composite function,and the time-varying model of splitting tensile strength and elastic modulus can take power function.