Inspection Of Concrete

Question 1

How do you clean for inspection

Answer 1

 Concrete is prone to abrasion so must be cleaned with care.
 An HP water-jet will effectively cut into the
concrete.
Acceptable methods of cleaning include:  Low pressure water-jet.
 Hand brushing with nylon brushes.
 Plastic hand scrapers.
 Brush-carts may be used if fitted with nylon brushes.

Question 2

Navigation & Positioning:

Answer 2

 Concrete structures are usually very large & relatively featureless.
 This makes navigation & location reporting particularly difficult.
 An ideal solution to this problem is to equip the inspector with an underwater transponder.

Question 3

Name another way to mark out for inspection

Answer 3

Another solution is to mark up a grid on the surface:
 This must be referenced to a known datum.
 The grid squares may be named alpha-
numerically.
 Imperfections may be reported by their grid coordinates.

Question 4

What is the drawback to using a grid

Answer 4

A major drawback of the alpha-numeric grid system is that it is time-consuming to set up.
A quicker solution is to use a down-line & distance-line technique, although the down-line may be replaced with a datum such as a riser.

Question 5

What are the reporting requirements

Answer 5

Reporting requirements for inspection will be specified by the Client’s Procedure & should be made explicit in the Inspection Controller’s briefing.
Include the following data in the verbal report:
 Location, type & severity of imperfection.
 Orientation &/or pattern.
 Extent of imperfection (length, width or
percentage).
 Maximum depth (penetration into the surface).

Question 6

How to define cracks

Answer 6

General Cracking:
 Well-defined cracks, length, width & shape is apparent.
Pattern Cracking:
 Forms a network best described by pattern & area.
When describing the width of cracks:
 Fine cracks: < 1mm
 Medium cracks:  1 to 2mm 
 Wide cracks: > 2mm