Application of Neutron Radiography to Observe Water Absorbtion of Concrete

It has been experienced that service life of reinforced concrete structures is often limited due to lack of durability of cement-based materials. One major reason for this durability problem is the penetration of water and compounds dissolved in water into concrete. Therefore, there is an urgent need to study water penetration into concrete in order to better understand deterioration mechanisms. Neutron radiography provides an advanced non-destructive technique with high spatial resolution. In this contribution, neutron radiography was successfully utilized to study the process of water absorption of two types of concrete with different water-cement ratios namely 0.4 and 0.6. It is shown that it is possible to visualize migration of water into concrete and to quantify the time-dependent moisture distribution with accurately and with high spatial resolution by means of neutron radiography. In concrete with high water-cement ratio, water penetrates much quicker than in concrete with lower water cement ratio. Water penetration depth obtained from neutron radiography is in good agreement with corresponding values obtained from capillary suction tests. Experimental results obtained by means of neutron radiography on water penetration into concrete will be presented and discussed in this contribution. Results will provide us with a solid basis for a better understanding of deteriorating processes in concrete and other cement-based materials. These results may be considered to be a first step to improve durability of concrete.