Study On Rule Of Radon Exhalation And Inhibition Effect Of Doping Fly Ash Test Blocks

Fly ash has been widely used in the production of cement and brick and other building materials.In recent years,with the attention to indoor radon pollution,the development of building materials with low radon exhalation has become a research hot spot.Therefore,the law of radon exhalation and the inhibition effect of fly ash-doped test blocks were studied.Firstly,the pollution and control of indoor radon were reviewed,and the model of radon diffusion migration of building materials and related theories were introduced.Next,based on the theory model of radon exhalation in porous emanation media of spherical building materials,a method for determining the parameters of radon diffusion migration in porous emanation media such as building materials was proposed.Then,a set of experimental equipment was optimized to measure the radon exhalation rate of building materials under different temperature and humidity.Finally,fly ash-doped test blocks with different formulations were made to study the radon inhibition effect of different methods.The specific research contents and conclusions were as follows:?1?Based on the theory model of radon diffusion migration of spherical porous emanation media,a method for determining radon diffusion coefficient and free radon production rate of porous emanation media such as building materials was proposed.The radon diffusion length of the hemispherical building material sample was 0.28m,and the diffusion coefficient was 1.74×10^-7m²·s^-1.The obtained results were compared with the previous experimental results to verify the feasibility of the measurement results.?2?A set of radon exhalation rate measuring device controlled by temperature and humidity was designed.The device can not only control the temperature and humidity of the environment in which the test media was located,but also measure the radon concentration in the radon collecting bin at different times under different temperature and humidity conditions?3?Taking the fly ash-doped test blocks?Original sample:fly ash 87.5g,cement 87.5 g,uranium tailings 525 g?as the research object,the effect of adding polyvinyl alcohol,sodium silicate to the test block and immersing the test block in saturated sodium silicate solution on restraining radon exhalation of fly ash-doped test block was studied.The following conclusions were drawn:1)When the additive amount was the same,the radon inhibition rate of fly ash with sodium silicate was higher than that with polyvinyl alcohol;When the additive type was the same,the radon inhibition rate of fly ash with 10%additive was higher than that with 5%additive;When the addition and variety of additives were the same,the radon inhibition rate of fly ash-doped test block increases with the increase of temperature.2)The original test block was immersed in saturated sodium silicate solution for seven days,and the radon exhalation rate of the test block before and after immersion was compared.It was found that the radon exhalation rate of the test blocks decreased after soaking,which proved that this method can effectively inhibit the radon exhalation of fly ash-doped test blocks.