Use of Infrared Thermography as a Standard in the Quality

Assurance and Quality Control of Grouted Masonry Construction

J.Eric Peterson, P.E., and Matthew J. Innocenzi, EIT

Whitlock Dalrymple Poston and Associates

8832 Rixlew Lane, Manassas, VA 20109

ABSTRACT

Current Building Codes and Standards specify the requirements for design and construction of masonry walls.

These codes also include requirements for different levels of masonry inspection. In spite of the fact that these

Codes and Standards set forth strict guidelines for the design of masonry walls, testing of materials, and periodic

inspection procedures, construction defects may occur and remain undetected. In particular, voids may be created in

the grouted cells of reinforced concrete masonry from obstructions, material deficiencies or incorrect placement

procedures. These flaws can significantly reduce the strength and water penetration resistance of the masonry wall.

These voids are typically the result of poor construction practices and are not visible to the naked eye. Infrared

Thermography (IRT) may be used by the inspector to distinguish the difference between hollow (or voided) and

grouted cells. Corrective action can then be taken to adjust the materials or the methods of construction and to

repair the voided masonry prior to the building’s occupancy.

This paper addresses how infrared thermography or thermal imaging can be used in detecting flaws that may occur

in reinforced masonry wall construction. Basic thermodynamic concepts are briefly discussed to describe the

applicability of IRT for masonry. A case history of successful implementation of IRT in new construction

inspection is presented. Limitations of this method are discussed to help prevent misinterpretation of test data.

Recommendations for implementation of infrared thermography as part of a standard inspection or quality assurance

program are discussed along with a sample framework for its organization.

Keywords:

infrared, thermography, masonry, grout, void, inspection, quality assurance, repair

1.

INTRODUCTION

Masonry is one of the most commonly used building materials in building construction. Virtually any building

erected today utilizes either clay or concrete masonry to form the foundations, walls, columns, or cladding systems

in some area of the structure. Masonry, when properly constructed, is a robust, versatile, and cost effective material

that effectively resists most loads commonly encountered in building construction. However, masonry must be

assembled by skilled tradesmen, and like many other building construction materials, errors and defects may result

from poor construction practices or material deficiencies.

Although many building materials can be visually inspected after construction to determine if the system was

installed in accordance with the design specifications, some components of masonry construction are not visible to

the naked eye. Grout is used in masonry construction to fill annular spaces inside concrete masonry units (CMU) or

between masonry wythes (parallel walls). If discontinuities or voids are present in the grout, they can reduce the

structural capacity of the system and, in the case of reinforced masonry, can limit the effectiveness of the steel

reinforcement and reduce the out-of-plane resistance to the lateral design loads. These voids can also collect water

leading to interior damage and corrosion of reinforcement.

Often, masonry is limited to periodic inspection as it is being constructed. However, as the masonry is constantly

erected in the field, it is difficult with periodic inspection to verify that mortar and grout are being properly placed.

Depending on the size of the project, it could require constant supervision of individual masons and laborers as the

project proceeds, which can be cost prohibitive for some owners. The industry as a whole recognizes the

importance of quality assurance in masonry construction and has modified the industry code requirements to reflect

the need for inspection that is both stringent enough to assure quality construction and varied enough to

accommodate both critical structures and non-structural masonry systems.

The Masonry Standards Joint Committee (MSJC) is responsible for the development of the Building Code

Requirements as well as the Specifications for Masonry Structures. This committee is comprised of representatives