Preparation And Properties Research Of Phase Change To Film Completely Impervious Concrete

The corrosive medium in the environment takes water as the carrier to enter into the concrete,which makes the performance of reinforcement and concrete deteriorate,and the applicability and safety decrease.The durability and safety problems caused by the poor impermeability of concrete itself are imminent.Especially for the prefabricated components,the high temperature curing system will cause more harmful holes and micro cracks in the concrete,resulting in serious deterioration of the impermeability of the concrete itself.In the face of the current situation that it is still unable to ground-breakingly improve the impermeability of such concrete components,this paper proposes to use hydrophobic phase change materials to ensure that they can dip and seal the cement stone structure after the phase change to film.Thus,the surface of pores and channels of the cement stone structure are hydrophobic,which can completely prevent water from permeating into the concrete,and ground-breakingly improve the impermeability of the concrete under the condition of high temperature curing.Several exploratory and innovative works has done in the following aspects in this paper:?1?Study on the Effect of Different Paraffin Based Phase Change Materials on the Basic Properties of Cement MortarThe effects of paraffin powder and paraffin emulsion on the fluidity,mechanical strength and impermeability of cement mortar were contrastively studied,so as to determine the best phase change material.The results showed that paraffin powder had a negative effect on the fluidity of cement mortar,but paraffin emulsion played a positive role in the fluidity of cement mortar;Paraffin powder and paraffin emulsion has adverse effects on the compressive strength of cement-based materials.Paraffin emulsion and paraffin powder after phase change have significant effect on the impermeability of cement-based materials,but the effect on impermeability of paraffin emulsion is slightly inferior to that of melted paraffin powder.?2?Study on Preparation and Carbonization Resistance of Phase Change to Film Completely Impervious ConcreteBy studying the influence of heating temperature and paraffin powder content on the mechanical strength,impermeability and carbonation resistance of cement-based materials,verifying the feasibility of preparing impermeable concrete,the most reasonable scheme can be determined.The results show that the paraffin powder will not lose efficacy and excessively exude because of high temperature.When the content of paraffin powder is less than or equal to 3%,the compressive strength of cement-based materials is less affected by melted paraffin and high temperature.When the content of paraffin powder is about 3%and the heating temperature is up to100?or above,the cement-based material can achieve long-term completely impervious effect.The paraffin protective layer can not only slow down the carbonization process of the specimen after high temperature heating,but also supplement the alkalinity of the carbonized area.?3?Microscopic Mechanism Analysis of Phase Change to Film Completely Impervious ConcreteThe influence of paraffin powder on the hydration process of cement was analyzed through the hydration heat test of cement.The mechanism of protection of paraffin phase change in cement-based materials was analyzed by observation of scanning electron microscopy and video electron microscopy.The results showed that paraffin powder has no obvious adverse effect on the hydration heat release of cement.The structure of paraffin protective layer is multi-layer overlapping,and the adhesion and encapsulation of layer are excellent.The paraffin content is the most dense within5mm below the surface of the paraffin phase change cement mortar,which not only effectively prevents the infiltration of water,but also plays a crucial role in resisting carbonization.?4?Study on the Effect of Surface Protection of Paraffin Emulsion on the Properties of Cement MortarThe water absorption and carbonization resistance of the specimens brushed paraffin emulsion of different quality were compared to determine the most reasonable brushing quality.The results showed that with the increase of the amount of paraffin emulsion,the water absorption and carbonization depth of cement mortar gradually decreases.The specimens with single-sided brushing quality more than or equal to 3g are not carbonized obviously for a long time in the environment of high CO₂ concentration.There are 53 figures,21 tables and 94 references in this paper.