Study On Mechanism Of Deterioration And Damage Of Marine Cement-based Materials

With the rapid development of China's social economy,inland resources are being consumed in large quantities,and the demand for marine resources is increasing.Under the guidance of China's "marine power" strategy,the development and utilization of marine engineering structural materials is becoming increasingly important.The content of marine cement-based materials is very rich.In this paper,marine cement-based raw materials(seawater and sea sand)are used as the main body of the study.An appropriate mix ratio is designed,and then samples are prepared for conservation.When the conservation reaches the design age,energy spectrum analysis is used.(EDS),X-ray diffraction test(XRD),electron microscopy(SEM)and other multi-scale experimental methods to observe and analyze the loading damage of marine cement-based materials to reveal the damage mechanism of marine raw materials in a multi-scale sense.The research work and results are as follows:The research first uses multi-scale and multi-directional micro-mechanical testing methods and conventional physical and chemical index experiments to systematically test and analyze marine cement-based raw materials(seawater,sea sand,cement)to obtain basic physical and chemical properties of various raw materials,such as The ionic composition of seawater,the characteristics of sea sand ore facies,and the distribution of aggregate particles,etc.,then the effects of these factors on the physical and chemical properties and engineering mechanical behavior of samples prepared from marine cement-based materials were investigated.According to the nature of raw materials and relevant specifications,design the mix ratio of cement-based materials,prepare samples and maintain them.When the design age is reached,perform uniaxial loading tests,and then use micro-mechanical testing to test the test blocks analysis.The micro-damage process of cement-based materials can be summarized as:as the loading stress increases,the weak parts of marine cement-based materials begin to be affected,and the hydrate layers of C-S-H,C-A-S-H and N-A-S-H gels are partially broken to form volume cracks.The needle-like AFt(ettringite)was broken,and the debris was blocked and expanded the volume crack.Multiple volume cracks eventually formed microcracks on the surface of the test block.The microcrack pores gradually expanded with time,and the depth of the cracks also increased.Constantly deepening,the test block was eventually destroyed when the compressive strength peak was reached.This study can be summarized as follows: using relevant micro-meso research methods,testing and analyzing the micro-mechanical changes,composition and macro-mechanical properties of test blocks prepared from marine raw materials,and exploring the typical damage process of typical marine mortars.Physical and chemical mechanism.