Non-destructive test methods are often used in tunnel construction to check the required lining thicknesses. Hereby, mostly ground penetrating radar, impact-echo and ultrasonic echo are applied. However, the current knowledge and experience is largely limited to testing the concrete thickness of double-shell tunnels. Problems with the application of non-destructive test methods can arise, when ...

There are many avenues to studying or recommending economic policy. Most common in public debates is an approach, where someone offers some amazingly precise policy conclusion (‘‘the age of mandatory retirement should be 67’’) based on an equally amazingly vague or secondary policy objective (‘‘financial viability of the pension system in the long run’’). Similar examples abound in monetary pol...

This paper has carried out an experimental program to establish a relatively accurate relation between the ultrasonic pulse velocity (UPV) and concrete compressive strength. The involved testing cubes of (100) mm prisms (100×100×300) cast with specified test variables. samples are tested by using equipment two methods, direct (DUPV) surface (indirect) (SUPV) for each sample. obtained results we...