Theoretical And Experimental Study On Cement-Based Materials Contains CO₂ And Harzard Wastes（Nuclides And Fly Ash）

With the gradual improvement of mankind’s level of social modernization, the industry is becoming increasingly developed, the urban living standards are changing with each passing day, people’s happiness is also constantly improving. But the consequent environmental problems can not be ignored, as a result of greenhouse gas emissions, the phenomenon of the global warming appeared, the radioactivity of the nuclear industrial waste must be properly disposed of, the difficulty of cities’ living garbage disposal lead to the cities are besieged by garbage, with the worsening of environment, environmental protection has become one of the core topics in the current world. This paper will see from the angle of the hot environmental issues mentioned above, it discusses to solidify nuclear waste and waste incineration ashes by using cement curing technology, and store carbon dioxide in the solidified body by using supercritical carbonation technology, thus forming the new cement material of storing carbon and solidifying the waste.The carbonation of concrete has been considered as one of the major diseases of the steel concrete structure, but for the cement base materials without the need of reinforcement, the carbonation can improve the micro structure, decrease the porosity and increase the density of the cement-based materials, which are all beneficial to the benign changes of the material properties. When the cement materials are placed in the environment of supercritical carbon dioxide, it can complete the carbonation process in a few hours, which requires a number of years to even more than ten years under the natural conditions, so by applying the supercritical carbonation technology in cement-based materials, it has the prospect of development of utilization. Nowadays, there are more and more researches on the curing hazardous waste and pollutants of cement materials, with the maturity of the cement curing technology, and the advantages of the stability and safety of the solidified body, the technology has become the most widely used waste curing method. In this paper, by combining the super-critical carbonation and the cement curing technology, it will further the safety of the solidified body and the effect of carbonation on the properties.The research process is carried out by means of the combination of experiments and the numerical model. In the process of the numerical model, the application scope of the original carbonation model is improved by introducing the parameter Cmax. Meanwhile, the influence of carbonation on solidifying the ion chemical leaching activity within the body in the model is first considered, and the accuracy and applicability of the binding model are improved. In the experiment, the solidified body of cement containing non-radioactive isotopes and waste incineration flying ashes was produced, the directly leaching experiment and the leaching experiment after carbonation were conducted on the curing sample, the change of leaching rate in the leaching process was observed, by comparing the results before and after carbonation, the effect of carbonation on the leaching properties of the solidified body was studied. The combination model of carbonation and leaching was established in the multi-physical field coupled finite element calculation software COMSOL by according to the theory of numerical model and the existing parameters, and the experimental process of carbonation and leaching of the solidified body was simulated. In summary, by the trinity of theory, experiment and simulation, the effect of carbonation of the leaching performance of the solidified body, as well as the applicability of the numerical model were commonly verified.