Mechanism Research On Wind-sand Erosion And Freeze-thaw Coupling Damage And Service Life Prediction Of Pumice Concrete

Lightweight,energy-saving,large-span,high-rise and smart are characteristics of modern buildings,new lightweight concrete meets the future development direction of concrete manufacturing.Therefore,full use of pumice resources,research and development of cement,pumice,sand,fly ash,i.e.,mixed pumice lightweight aggregate concrete,for the construction of infrastructure in northern China has good social and economic value.The study area in this paper is in the northwestern region of northern China.The area is cold and windy in winter and spring.The concrete structure is exposed to unfavorable natural environments such as freeze-thaw cycles and wind-sand erosion for a long time,which may easily affect the durability and safety of the structure,resulting in structural Reduced service life creates potential safety hazards.Based on the characteristics of the northern environment,the actual natural environment of the pumice concrete structure was simulated,the failure mechanism was analyzed,and the durability prediction model was established.The specific research content is as follows:1.Using the wind-sand erosion system to simulate the actual sandy environment,the damage of the pumice concrete was explored by changing the time of erosion,the angle of erosion,the speed of wind erosion,and the rate of sand-drop.Using Z16 APOA Lecia 3D Super Depth Digital Microscope to observe the test phenomenon and analyzes the damage morphology of the pumice concrete's wind-sand erosion.2.The durability of pumice concrete under wind-sand erosion and freeze-thaw coupling damage was studied through the airflow sand-carrying method and quick freezing method,the change rule of mass loss and relative dynamic elastic modulus was analyzed and the nuclear magnetic resonance and Scanning Electron Microscopy were performed to investigate the changes in inner damage.3.Based on the damage evolution equation of concrete life prediction,the linear + quadratic acceleration decay curve model of the freeze-thaw cycle of pumice concrete and the linear + secondary deceleration decay curve model coupled with the wind-sand erosion and freeze-thaw were quantitatively established.The model is consistent with the actual test points,and can predict the service life of pumice concrete in the freezing-thawing environment and the wind-sand erosion and freeze-thaw cycle coupling.The damage model also provides a theoretical basis for the use of pumice concrete in northern China.