| Marine engineering and national defense military are the key constructionprojects of country, which usually requires high durability and safety. Concreteconstitutes the main body of ocean engineering and military project as the mainconstruction material. Durability of concrete can directly affect the life of marineengineering and military project. The environment of the marine engineering isespecially bad, such as suffer tide, wind erosion, seawater Cl-and SO42-ioncorrosion, which will accelerate the concrete and internal steel erosion. This thesismainly investigated the durability of concrete and concrete hydration mechanism. Itwill have great significance to marine engineering concrete durability design.On the basis of previous studies, the adhesive sand and concrete mechanicalperformance and durability were investigated through changing the differentparameters and the geopolymer was analyzed by Scanning Electron Microscopy,X-ray diffraction and hydration heat instrument. Concrete macro performancecharacterization was also analyzed by bending testing, HP-4.0anti-permeability,RCM rapid chloride ion diffusion instrument. The geopolymer gel-material was akind of particle distribution uniform non-crystalline material, and its particle sizeranges from5μm to10μm and has a low crystalline phase content in the geopolymermaterial. The result of EDX showed that composite material mainly contained O, Si,Ca, Al.In view of the question of the present concrete low durability, changing durableinfluential parameters were commenced in the paper. The adhesive sand sampleswere prepared to determine the range of some parameters, such as ratio of water andgeopolymer, content of fly-ash and so on. The compressive strength of adhesivesand sample could reach78MPa, and flexural strength could reach14.8MPa as ratioof water and gerpolymer was0.35. When fly-ash particles were used10wt%ofadmixture, compressive strength and flexural strength would reach the maximumvalue. These parameters can provide theoretical basis for the process of preparedconcrete.On the other hand, the research of Hydrophobic powder influence on thedurability of concrete is conducted. Hydrophobic powder is a new kind of mixture,whose structure is complex of silane and siloxane. Its main elements include C, O,Si. The experiment showed that Hydrophobic powder had little influence on themechanical strength, but could greatly enhance the durability of concrete. Thepermeability level of concrete sample added water-resistant can improve3～4grades, and also can reduce the chloride ion diffusion coefficient to be below 2.0×10-12m2/s. The mechanism of Hydrophobic powder was that, under highalkaline environment of geopolymer hydration process, hydrophilic organicfunctional groups in silane hydrolyze form high reactivity of silanol group, andsilanol group will continue to work with hydroxyl group exist in hydration products.As a result, irreversible reaction forming chemical combination happened. Reactionproducts fill the micro cracks and micro hole on the sample surface to make samplesurface denser, achieving the purpose of improving the durability.The innovation of this thesis lies in the study of hydration mechanism in thecementing material. A kind of new material---long lasting persistence luminescentmaterial was used. Due to the process of geopolymer hydration mechanism is morecomplex, and the interface is difficult to define, in order to solve this problem,during the process of experiment, adding one kind of material that is similar togeopolymer in the element, which can clearly distinguish on morphology. At last, wechoose strontium aluminate long lasting luminescence material. This is a kind ofsubstance that through external light excitation can emit fluorescent light. Throughthis material we can clearly distinguish the interface between geopolymer and longlasting luminescence material, and elements migration would be clearly seenthrough the line scan. Accordingly, geopolymer hydration degree could be furtherspeculated. |
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