Type of Document Master's Thesis Author Khuri, Ramzi Emile Author's Email Address rkhuri@vt.edu URN etd-020999-153357 Title Performance-Based Evaluation of Joint Sealants for Concrete Pavements Degree Master of Science Department Civil Engineering Advisory Committee
Advisor Name Title Al-Qadi, Imadeddin L. Committee Chair Dillard, John G. Committee Member Weyers, Richard E. Committee Member Keywords
- Concrete Pavements
- Joints
- Sealants
Date of Defense 1998-12-04 Availability restricted Abstract Pavement concrete joints are the weakest locationsin concrete pavement systems. They are man-made
cracks to accommodate concrete slab expansion and
contraction due to temperature fluctuations.
Sealant is usually used in pavement joints to
prevent roadway debris, deicing chemicals, and
moisture from entering the joint. When sealant
fails, the pavement deteriorates rapidly; and
when joint sealant performs adequately, the
pavement preserves its intended performance. In
the field, joint sealant undergoes two types of
mechanical loading simultaneously. The sealant
is experiencing tension or compression as slabs
contract (low temperature) or expand (high
temperature), respectively. Sealants also
experience shear as heavy trucks travel over the
joint and deflect the ends of the pavement slabs.
In addition, sealants may also be exposed to a
variety of environmental conditions, such as
moisture, ultraviolet light, and jet fuel, which
in some cases could be detrimental to their
performance. In this study, the effects of
vehicular and environmental loading on joint
sealant performance were evaluated. To simulate
the sealed joint performance, specimens were
constructed by sandwiching a sealant between
two 50.8 mm Portland cement concrete (PCC) cubes.
Prior to mechanical loading, specimens were
subjected to partial immersion in distilled water,
partial immersion in jet fuel, and/or exposure to
UV-A light. The specimens were then subjected to
static horizontal tension, simulating slab
contraction, and cyclic deflection-controlled
shear, simulating heavy trucks travelling over
the joint. The cycle consists of one 0.2 second
period of sinusoidal loading (total 6.4 mm
deflection) followed by a 0.4 second relaxation.
The mechanical loading was applied using a
special fixture developed at Virginia Tech, which
is connected to a closed-loop servo-hydraulic
loading machine. Two types of sealants (preformed
neoprene and field-molded silicone with a primer)
were tested using PCC mixes with two different
aggregate types. In, addition, two different
joint widths were evaluated for each sealant type.
From the results of the cyclic testing and
environmental conditioning, it was shown that
the use of a primer greatly enhances the
performance of the silicone sealant used with
concrete containing limestone aggregate. In
addition, severe swelling occurs when silicone
sealant is exposed to jet fuel, and the failure
of the field-molded silicone initiated at the
bottom of the sealant and propagated upward.
The preformed neoprene sealants proved very
durable despite any combination of environmental
conditioning, provided that the sealant remained
in compression.
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