Detection of Voids in a Reinforced Concrete Wall

Occasionally, after formwork has been stripped site personnel are confronted with a visual disaster. While modern materials can be used to repair the surface of honeycombed concrete to acceptable standards, the engineer is often concerned that the surface conditions might reflect internal defects which could seriously affect the structural integrity of the system. Recent advances in ground penetrating radar (GPR) equipment coupled with advanced computer enhancement of the radar scans enables GPR technology to provide a reliable images of the interior of concrete structures. Click here to read more

Detection of Voids in a Concrete Slab

Difficulties arose during the construction of the spillway of a dam. Constructed monolithically in two 0.5 m layers, it was suspected that voids were present between the layers. The owners and their consultant PJ Materials Limited considered that it was imperative to detect and rectify the problem, to prevent premature deterioration due to freezing and thawing. Ground Penetrating Radar (GPR) was used in tight parallel traverses across the surface of the slab which were subsequently analyzed by computer to produce images of horizontal slices through the data. Click here to read more

Impact-Echo Tests on Historic Monument

The monument was constructed in two layers, an outer shell of mortar and boulders and an inside concrete shell. The inside shell was showing signs of deterioration including moisture penetration and frost damage. It was considered probable that there was also deterioration at the interface between the two shells. In 1995, impact-echo tests were completed in a grid pattern of 1 m. The results confirmed that there were locations where the wall thickness was quite thin confirming that there was deterioration between the inside concrete shell and the outer shell of mortar and boulders. In 2000 a second set of impact-echo tests set of revealed that the deterioration was considerably greater. Contour maps of the both sets of test data were constructed enabling visual comparison of the ongoing deterioration. Click here to read more