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attentionmust be paid to its adequacy to use and its relatively short
service life (approximately 5 years). Johnson and Cuninghame [3]
found out that 24.6% of the asphaltic plug joints inspected had
no apparent defect, 11.9% were cracked, 36.4% were tracked, and
27.1% were debonded (furthermore, 50% of these joints leaked,
almost half of which had no apparent defect). Also open joints
(JA), buried joints under continuous surfacing (JOPC) and preformed
compression seal joints (JPEC) are fundamentally affected at the
level of the pavement and its transition to the joint (category
AA). As expected, defects in category AD were detected only in
prefabricated joints such as elastomeric flexible strips (BFE), steel
sliding plates (PMD), and reinforced elastomeric cushion joints (JEA).
Reinforced elastomeric composed joints (JEAC) that were inspected
did not reveal defects in terms of fastening. This can be due to
a lesser stiffness of this type of joints especially when compared
with plain reinforced elastomeric cushion joints. In fact, Johnson
and Cuninghame [3] reported that some of these last joints had
anchorage problems, besides approximately half that had cracked
transition strips (a situation highly dependent on the level of
maintenance), and 65% that leaked. As for cantilever-finger joints
(PMC), no conclusions could be drawn because the joints of this
type that were inspected revealed no defects.
The average number of defects per joint versus the joint type
was determined (see Fig. 4 for abbreviations): JA (3.5), JOPC (2.0),
JBM(1.8), JSME (5.0), JPEC (3.2), BFE (3.4), PMD (4.3), JEA (2.2), PMC
(0.0), and JEAC (1.4). Even though the analysis is conditioned by
various particular characteristics of the sample, it leads to various
conclusions.
Nosing joints with poured sealant (JSME) and steel sliding plates
(PMD) are those that presented the highest average number of
defects, possibly due to the higher age of the bridges with these
joints (27 years). Nevertheless, due to the level of degradation they
present, nosing jointswith poured sealant seemto have a relatively
short service life.
Of themost common and thereforemore reliable types of joints
in the sample, elastomeric flexible strips (BFE) present a higher
tendency towards defects than reinforced elastomeric cushion joints
(JEA). Thus the latter seem to justify their high application ratio
since their average number of defects is one of the lowest in
the sample. Johnson and Cuninghame [3] reported that BFE's
most common defect was incompatibility between the movement
capacity of the joint and the actual deck movements (debris built
up was also noticed and 38% of the joints leaked).
It must be pointed out that the absence of defects in cantilever-
finger joints (PMC) is in a great deal caused by the fact that only
4 such joints were inspected, all of them installed very recently.
Nevertheless, since various defects come up at the initial stages of
service, this absence is a good omen in terms of reliability of this
joints type.
3.4. Causes of the defects
In the sample inspected, 637 causes of defects were identified
corresponding to an average of 1.71 causes per defect. Out of a
universe of 33 potential causes that comprise a classifying list
(presented in [1]) 26 were detected. Similarly to the defects list
there was a need to adjust some of the designations adopted
initially.
In order to pursue an overall analysis of the results, the
distribution causes in percentage of all, direct and indirect, for each
of the established categories has been determined: CA design
errors (1), CB prescription errors (7), CC manufacturing errors
(8), CD installment errors (38), CE lack of maintenance (28),