Nondestructive Measurement for Water and Voids in Concrete with Compact Neutron Source

Abstract

The authors have developed a nondestructive inspection method using backscattered neutrons to detect voids and water in concrete with a RIKEN Accelerator-driven Compact Neutron Source (RANS). In this study, neutrons are emitted to a slab sample that consists of a concrete layer and an asphalt layer, and position distribution of backscattered neutrons are measured at the timing from 0.1 to 0.5 ms. The two-dimensional position of water and voids in the concrete plate under asphalt (5 cm) of the slab sample are detected.

RIKEN Accelerator-driven compact neutron systems

“…The fast neutrons penetrate through more than 20 cm concrete or asphalt layer of pavement. By choosing the proper timing and the energy of the back scattered neutron, the visualization of the water or air hole in the floor slab behind the first layer of the pavement [15].…”

RIKEN Compact Neutron Systems with Fast and Slow Neutrons

“…Because it is known that the deterioration of a concrete slab can be due to the negative influence of water, "Waterproof layer of reinforced concrete slab on road bridge: Design and construction (1987)" [7] first specified the fullscale provision of waterproofing for slabs. A novel method of backscattering (reflection) neutron imaging method to detect water and voids in concrete has been developed with RANS for its application to non-destructive inspection to determine the deterioration situation, such as resident water and voids in concrete slabs under asphalt pavement surfaces from the road surface side [9]. Two-dimensional imaging of water or voids can be obtained with time-offlight experiments.…”