Handbook of Sealant Technology

2016

Sealants are commonly used to insulate cracks and joints preventing water from entering the underlying structure. However, extended exposure of sealants to water has shown to negatively impact sealants properties causing gradual degradation of sealant performance. While there have been many studies on characterizing sealant performance in dry conditions, there has been no comprehensive experimental tests to evaluate crack sealants water susceptibility based on a fundamental material property. This study introduces five laboratory tests to investigate the effect of water exposure on different crack sealants commonly used in cold, moderate and hot climates. Sealants were acquired in collaboration with University of Illinois Urbana-Champaign. Experimental plan includes several thermo-mechanical and surface characterization tests. Crack sealants' rheological properties and relaxation time was measured using a Dynamic Shear Rheometer (DSR). Sealants' creep compliance was measured using an extended Bending Beam Rheometer (BBR). In addition, a direct adhesion test was incorporated using a Direct Adhesion Test (DAT) machine to determine the load required to bring sealant specimen to adhesion failure. Surface tension was measured using a Goniometer. A higher reduction in surface tension indicates sealant has more susceptibility to water. Chemical structure and formation of any new functional groups was tracked using Fourier Transform Infrared (FTIR) spectroscopy. The extent of change in aforementioned sealant properties before and after water conditioning was used as indicators of sealant susceptibility to water. The experiments results were compared against sealants' field performance data obtained through the Pooled-Fund Crack Sealant Consortium led by the

American Journal of Engineering and Applied Sciences, 2011

Problem statement: Crack sealing and filling is the most widely used maintenance activity for in-service pavements. If an appropriate sealant material is selected and properly installed at the appropriate time of the pavement life, it retards pavement deterioration and increases its service life at a relatively low cost. However, in some cases it is reported that sealants failed prematurely, mainly due to environmental factors and water exposure. While there have been several studies on environmental factors, water related factors has not received appropriate attention. Nevertheless, various sealants have different water resistance property; hence, they perform differently when exposed to large amount of rain and humidity. Approach: Currently, there is no standard test method to evaluate sealant water resistance. Therefore, there is a need for a standard test method to precisely predict sealant performance when exposed to water. Such a test method can help examine various sealants in terms of their water resistance. This study introduces water conditioning procedure and a test method to measure bond strength of sealant under dry and wet condition. The effect of water on the Interfacial Fracture Energy (IFE) of bituminous sealants was measured by means of a blister test. This test allows the calculations of two fundamental parameters: tensile modulus and the Interfacial Fracture Energy (IFE). Results: Experimental results showed water exposure caused a significant drop in adhesion strength. However, no significant difference was observed between adhesion strength of specimens conditioned for 8 and 12 h of conditioning. Conclusion/Recommendations: The proposed approach and testing method can be used by the sealant manufacturers to improve their sealants' adhesion properties at the presence of water. However, further research works are needed to examine how sealant adhesion strength varies with water exposure duration. Also, the effect of water pH on sealant adhesion strength can be studied.

https://www.ijrrjournal.com/IJRR_Vol.8_Issue.1_Jan2021/IJRR-Abstract063.html, 2021

Dental sealants were introduced in 1960's to prevent occlusal dental caries. They arrest the growth of caries causing bacteria, preventing their progression and subsequently avoiding early caries. Dental sealants act as caries preventing agents only till the time they remain bonded to the tooth. The intent of this review is to focus on dental sealant materials, discussing their effectiveness in preventing caries, caries risk assessment between sealant protective and no sealant tooth, compare different types of sealants-on the basis of their effectiveness, newer advances in sealant placement and elucidate upon the harmful effect of bisphenol A, a regular component of dental sealants.

degradation, even at recommended installation temperatures." The absence of field studies, however, may have prevented the widespread recognition of possible sealant degradation during installation.

It is difficult to evaluate effectively the low-temperature stiffness of bituminous hot-poured crack sealants with existing test methods. The standard bending beam rheometer (BBR) was found to be inappropriate for testing soft bituminous-based hot-poured crack sealant, even at a temperature of −40°C. To address this issue, the moment of inertia of the tested beam was increased by doubling its thickness (from 6.35 mm to 12.7 mm). For the new beam dimensions, only 4% of the beam center deflection is due to shear, a value deemed acceptable for sealant evaluation and comparison. On this basis, the BBR stiffness of hot-poured sealants was obtained at several discrete temperatures between −10°C and −40°C to assess the repeatability of the method for the evaluation of the low-temperature stiffness of bituminous sealants. Ten different sealants were tested at −40°C; three of these 10 were further tested at −35°C, −30°C, −28°C, −25°C, and −20°C; and the three "hard" sealants were tested at −10°C. A minimum of three replicates were used. The coefficient of variation on the measured stiffness after 60 s of loading was always lower than 18%, with almost 75% of the measurements having a coefficient of variation less than 10%. A pairwise comparison showed that the modified BBR could be used to classify sealant products according to their measured stiffness. As to the effect of temperature, it was found that the stiffness varies exponentially with temperature in the range of −40°C to −20°C. A statistical analysis of the results indicated that the modified BBR method could be used to classify sealants based on low-temperature stiffness.

The Review of scientific instruments, 2013

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise m...

Journal of Clinical Pediatric Dentistry, 2000

A well-fitted root canal filling prevents percolation and microleakage of periapical exudate into the root canal space, prevents reinfection and creates a favorable biological environment for healing to take place. Several techniques using gutta-percha have been used in an attempt to achieve a void-free, homogeneous filling. Aim: Three different obturation techniques that are Thermafil obturation, cold lateral condensation and warm vertical condensation using rotary canal technique were compared.

International Journal of Clinical Pediatric Dentistry, 2019

Aim: The aim of this study is to determine the retention rate and pattern of different pit and fissure sealants placed on the occlusal surface of newly erupted first permanent molars after 3, 6, 9, and 12 months. Materials and methods: Seventy children were enrolled in this study. They divided into seven groups (m = 10) according to the type of the sealant. The four permanent first molars of each child were sealed. The sealant was applied according to the instructions from the manufacturer. A clinical evaluation was carried out at 3, 6, 9, and 12 months. The clinical observations were divided into three categories: total retention (TR), partial retention (PR), and total loss (TL). Results: The resin-based sealant performed better than the glass ionomer-based sealant except for the Ketac Molar Easymix. At 3 months, there was no significant difference among all the tested groups (p > 0.05), while at 6, 9, and 12 months, there was a highly significant difference (p < 0.001). The glass carbomer sealant showed the least retention rate at all intervals. Conclusion: With an exception of the Ketac Molar Easymix, resin-based sealers performed better than glass ionomer-based sealers. Clinical significance: A proper application of pit and fissure sealant will decrease the chance for caries development in newly erupted teeth.

Journal of Engineering Design, 2001

A design software, based on CAD and FEA tools, was set up for the parametric analysis of bolted joint connections with adesive sealants; this software can be used for a low cost evaluation of joint performances. To this aim the mechanical properties of two typical anaerobic and silicon based sealants were experimentally obtained by means of an optimized specimen. 2D and fully 3D FE models of bolted connections were developed for taking into acount bolt preload and position, flange thickness, internal pressure and mechanical properties of sealant material. Non linear contact analysis was employed for a realistic joint simulation. Results provide the tensile stress distribution in the sealant along the joint middle layer, for any user-specified configuration. A user friendly software tool was then developed for speedy evaluation of commonly used joint geometries.