Nielson K K, Rogers V C, Holt R B, Pugh T D, Grondzik W A, de Meijer R J
Rogers and Associates Engineering Corporation, Salt Lake City, UT 84110-0330, USA.
Health Phys. 1997 Oct;73(4):668-78. doi: 10.1097/00004032-199710000-00013.
Radon movement through 12 test slabs with different cracks, pipe penetrations, cold joints, masonry blocks, sealants, and tensile stresses characterized the importance of these anomalous structural domains. Diffusive and advective radon transport were measured with steady-state air pressure differences controlled throughout the deltaP = 0 to 60 Pa range. Diffusion coefficients (deltaP = 0) initially averaged 6.5 x 10(-8) m2 s(-1) among nine slabs with only 8% standard deviation, but increased due to drying by 0.16% per day over a 2-y period to an average of 2.0 x 10(-7) m2 s(-1). An asphalt coating reduced diffusion sixfold but an acrylic surface sealant had no effect. Diffusion was 42 times higher in solid masonry blocks than in concrete and was not affected by small cracks. Advective transport (deltaP < or = 60 Pa) was negligible for the slabs (10(-16) m2 permeability), pipe penetrations, and caulked gaps, but was significant for cracks, disturbed pipe penetrations, cold joints, masonry blocks, and concrete under tensile stress. Crack areas calculated to be as small as 10(-7) m2 significantly increased radon advection. Algebraic expressions predict air velocity and effective crack width from enhanced radon transport and air pressures. Masonry blocks, open cracks, and slab cold joints enhance radon penetration but stressed slabs, undisturbed pipe penetrations, and sealed cracks may not.
氡气通过12块带有不同裂缝、管道贯穿、冷接缝、砖石砌块、密封剂和拉应力的测试板的运动，体现了这些异常结构区域的重要性。在整个ΔP = 0至60 Pa范围内控制稳态气压差，测量氡气的扩散和平流传输。在最初的九块板中，扩散系数（ΔP = 0）平均为6.5×10⁻⁸ m² s⁻¹，标准偏差仅为8%，但在两年时间里由于干燥作用每天增加0.16%，平均达到2.0×10⁻⁷ m² s⁻¹。沥青涂层使扩散降低了六倍，但丙烯酸表面密封剂没有效果。实心砖石砌块中的扩散比混凝土中高42倍，且不受小裂缝影响。对于测试板（渗透率为10⁻¹⁶ m²）、管道贯穿和填缝间隙，平流传输（ΔP≤60 Pa）可忽略不计，但对于裂缝、受干扰的管道贯穿、冷接缝、砖石砌块以及受拉应力的混凝土则很显著。计算得出小至10⁻⁷ m²的裂缝面积会显著增加氡气的平流。代数表达式可根据增强的氡气传输和气压预测空气流速和有效裂缝宽度。砖石砌块、开放裂缝和平板冷接缝会增强氡气渗透，但受压平板、未受干扰的管道贯穿和密封裂缝可能不会。
