Handbook for Bridge Inspections - TSP2

7.5 Adequate Materials
Investigation - Timber
This chapter contains in formation about materials investigations
which can be recommended for Ihe inspection of timb er bridges
and bridge elements.
Figure 7. 5-/: Measurillg Mois/ure
Le l'e/s in Wood
Purpose
7.5.1 Investigation of the Humidity Level of
Timber
To measure the moisture content of timber elements. The moisture
level recorded wi ll reveal, amongst other things, whether there is a
danger of the existence of dry rot fun gus. This test will, however,
be of usc only in special cases and only for load-bearing clements
since an already high moisture level must be taken into account in
limber bridges .
• Electric moisture meter
• Measurement electrodes
Purpose
7.5.2 Checking for Fungus and Rot - Timber
To carry out analyses of timber in order 10 ascertain the type of
fun gus wh ich has ca used the rot damage. These are worth consideri
ng when the test area is large and any possible replacement of
sections could have serious consequences.
Procedures
Equ ipment/Com petence
Samples should be taken of any fungus visible and these are to be
sent 10 a laboratory which conducts tests on fung i.
A pi ece of wood core can also be extracted using a drill to obtain a
picture of the timber's cross-section. The core removed should be
of the smallest possible diameter so as to avoid weakelling the
cross-section. The hole should be re-fi lled.
Samples should be removed with a knife or other equipment for
drill ing out core sections. The analyses should be conducted by a
specially equipped laboratory with com petent personnel.
7.6 Adequate Materials
Investigation - Stone
In the fo llowing secti on a description is provided ofth e materials
testing which can be used during inspections of stone bridges and
bridge clements.
Purpose
7.6.1 Compressive Strength for Stone
To ascertain the compressive strength of stone by press ure testing.
This may be necessary when checking the load bearing capacity of
slone bridges.