Title page for ETD etd-020999-153357


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 locations

in 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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