Characteristic parameters and radon exhalation rates of aerated concrete blocks

Objective

To understand the characteristic parameters and radon exhalation rates of aerated concrete blocks.

Methods

A total of 39 nationally inspected samples were measured. Their dry density was determined based on their mass and volumes, their porosities were measured on the principle of volumetric expansion, and their radium content was determined using a high-purity germanium (HPGe) detector for gamma-ray spectroscopy. Furthermore, their diffusion lengths were quantified by establishing a combined cumulative and diffusion chamber, and their radon exhalation rates were measured through closed-box testing using a continuous radon monitor.

Results

The aerated concrete blocks exhibited dry densities ranging from 464 to 840 ​kg/m³ [average: (654.0 ​± ​82.5) kg/m³], open porosities from 67.1% to 81.1% [average: (74.3 ​± ​3.3) %, radium (²²⁶Ra) content from 12.3 to 136 Bq/kg [average: (63.0 ​± ​30.4) Bq/kg], diffusion lengths from 0.49 to 1.01 ​m [average: (0.70 ​± ​0.15) m], and radon exhalation rates from 0.6 to 22.8 Bq·m⁻²·h⁻¹ [average: (7.3 ​± ​5.3) Bq·m⁻²·h⁻¹].

Conclusion

Aerated concrete blocks exhibit significantly higher porosities, diffusion lengths, and radon exhalation rates than traditional concrete and clay bricks. These blocks might contribute to the high indoor radon concentration observed in modern buildings in China.