Vivek Tandon, PhD, PE Associate Professor, The University of Texas at El Paso, El Paso, Texas, USA.

Tack coat is a light application of emulsion or bituminous binder between existing roadway surface and the new overlay. The main purpose of the tack coat is to bond the two layers to prevent slippage and efficiently transfer traffic loads from overlay to the existing surface layer. In the case of poor quality or improper application of the tack coat, the bond between the layers diminishes and the top layer slips away (figure 1). The end result is the development of various types of distresses in the pavement and the significant reduction of the life of the overlaid pavement system. State roadway agencies have traced failure of overlays to tack coat.

Tack Coat
Figure 1
Tack Coat
Figure 2

Although various laboratory devices exist for the evaluation of tack coat quality, an affordable device to evaluate quality of tack coat at the time of application in the field is not available. A study was conducted by the University of Texas at El Paso to develop the same under the guidance of Texas Department of Transportation (TxDOT). Based on the study, a UTEP Pull-Off-Device (UPOD) was developed (figure 2) to evaluate tack coat quality in the field. The device weighs about 16.6 lb (7.53 kg) and levels itself with the help of pivoting feet. It has a weight key on the top, which provides stability while placement of loads. A 3/8th in. (9.53 mm) nut fits a 3/8th inch drive torque wrench, which is used to pull the plate up from the tack-coated surface. The device consists of a 5-in. (127mm) diameter aluminum contact test plate.
Tack Coat
Figure 3

To add flexibility to the contact plate, a 5 in2 3M double-sided tape is used and attached to the aluminum contact plate and 5 in2 moisture bearing foam is placed over the tape. The advantage of the moisture bearing foam is that it can be easily peeled off the double sided tape and four to five tests can be performed before the adhesive layer (double sided tape) needs replacement. The 5 in. aluminum contact test plate and placement of adhesive layer as well as moisture bearing foam is shown in figure 3. A 6-150 in.-lb (152-68 mm-Kg) torque wrench is used for measuring pull-off torque. This torque is converted into load by using calibration factor of UPOD.
This is a premium article available exclusively for our subscribers.
If you are already a subscriber, please Login
If not, subscribe now and get access to well researched articles & reports on infrastructure construction, equipment & machinery, innovations & technology, project reports, case studies, and more. All this by simply paying just ₹200/- for a month of complete portal access, or a discounted rate of ₹1000/- for a full year of access.
GAEPL Achieves Record Paving of 100 lane-km in 100 hours
Ghaziabad Aligarh Expressway Private Limited (GAEPL), under the guidance of Cube Highways, has set an example of speedy, safe, and sustainable road construction through research, integration of advanced technology, following best international practices

Read more ...

Indian Companies Delivering Projects Overseas
External affairs minister S. Jaishankar during his visit interacted with the workers and the senior staff, and lauded the role of Indian infra companies, saying that he was “impressed by their enthusiasm”. “Strong economics will complement shared values in taking

Read more ...

NHAI awards 6,003 km of highway projects in FY23
According to Motilal Oswal Financial Services, the infra project awarding activity picked up and gathered pace in Q4 of FY23, with NHAI awarding total projects of 6,003 km in FY23, much below its FY23 target of 6,500 km. The total value of projects awarded

Read more ...

Is the Indian Road Sector Navigating a Smooth Journey?
This report covers the current state of the Indian Road Sector, performance of road projects under Hybrid Annuity Model, financial performance of major road developers, and the outlook for FY24. CareEdge Ratings analysed 235 HAM projects awarded between

Read more ...

Balanced Mix Design for Bituminous Mixes
As more than 90% of the roads in India have bituminous surfacing, a proper bituminous mix design also assumes significance for better performance of the bituminous roads. India is currently witnessing huge investments by the Indian Government towards

Read more ...

Sustainable Road Construction in Hilly Region
Siksha Swaroopa Kar, Principal Scientist, Amit Kumar, Technical Officer, Krishan, Technician, Flexible Pavement Division, CSIR-CRRI, New Delhi, discuss mechanized laying of cold bituminous layer, the mixer and paver that have been fabricated, and the effectiveness

Read more ...

Implementation of Road Maintenance Management System - Benefits & Technologies
The maintenance of road pavements is essential to ensure the safety, reliability, and sustainability of road networks. A road maintenance management system (RMMS) involves effective management of resources to optimize the life cycle of roads, reduce maintenance

Read more ...

Replacement of Steel Reinforcement with  Synthetic Fibre for Concrete Pavement & Floor
Manoj Didwania, Adani Total Gas Ltd, Dharamsinh Desai University (DDU-Nadiad), Cept University, presents a paper on the use of Macro Synthetic Reinforcement Fibre (MSRF) as full or partial replacement of Steel Reinforcement for Concrete Pavement

Read more ...

GTI® Reinforced Soil Slope System
GTI® is involved in developing environmentally friendly construction products and systems, which are critical for achieving infrastructure growth in a sustainable manner. The company’s GTI® Sloping Fascia Unit and the new system GTI® Reinforced Soil Slopes

Read more ...

CRISIL: Debt to rise for road developers amid strong revenue growth
Sizeable equity commitments in under-construction projects and rising working capital requirement will increase the debt burden of road developers, though revenue growth will also be high in the next two fiscals driven by strong awarding and execution

Read more ...

Indian Toll Roads to witness moderation in growth to high single digits in FY2024 after a stellar 17-20% growth in FY2023: ICRA
WPI for December 2022 is significantly lower at 5.0% against WPI of 14.27% in December 2021. ICRA Ratings expects the toll road projects growth to moderate to high single digit in FY2024 after a 17-20% growth witnessed in FY2023 with moderation in the

Read more ...

Road Over Umling-La Pass at 19,024 Feet
Construction of World’s Highest Motorable Road Chismule – Demchok In Eastern Ladakh Using Non-Frost Susceptible Sub-Base. Union Territory of Ladakh is located at approx 11,000 feet above Mean Sea Level (MSL). The area experiences extreme cold

Read more ...

BRO Uses Eco-Friendly Steel Slag For Road Construction
Steel slag, a by-product of steel making, is produced during the separation of the molten steel from impurities in steelmaking furnaces. This process generates slag as a molten liquid melt and is a complex solution of silicates and oxides that solidifies

Read more ...

Potholes to become history breakthrough by Zydex
Vadodara-based Zydex Industries has developed a new technology in road construction that enables roads to resist cracking under heavy traffic loads and cyclic weather variations. The speciality chemicals company has been at the forefront of R&D and implementation

Read more ...

Expected Increase in M&A and Refinancing Activity for HAM Projects in India: ICRA
According to the ratings agency ICRA, there is expected to be an increase in mergers and acquisitions (M&A) and refinancing activity in highway asset management (HAM) projects in the upcoming quarters. Approximately 105 HAM projects, with a total bid project

Read more ...

Prestressed Precast Concrete Pavement (PPCP)TM
PPCP Technology can help build roads of good quality, which are highly durable, can be built quickly, and do not require extensive maintenance. The construction industry is primarily concerned with two issues: construction quality control and the speed

Read more ...

More Efficient Road with iROADS Asset Management
iROADS Asset Management System enables significant optimization of road maintenance costs while ensuring a well-maintained road network and road assets. India has the second largest road network in the world comprising national

Read more ...

Upgradation of PMGSY Road Using Full Depth Reclamation Process in the State of Nagaland
Rapid growth in industrial development and economy in last two decades has demanded upgradation of the existing road network in the country. Though there is a huge road network in the country, it is still inadequate to meet accessibility and mobility requirements

Read more ...

Erosion Control for Green Highway Construction
Namrata Bichewar, Regional Manager - Maharashtra, Gabion Technologies India Pvt Ltd, discusses the company’s contribution in constructing green highways using Bio-Engineering Erosion Control methods and solutions. The government plans to construct 26 green expressways

Read more ...

Stone Matrix Asphalt is enabling durable and maintenance-free roads in India
A Stone Matrix Asphalt (SMA) pavement laid at Parimal Underpass in Ahmedabad Municipal Corporation has completed 7 years. The underpass, which used to get submerged under almost 2m depth of water due to waterlogging in the monsoons every year

Read more ...