Masonry Magazine April 1999 Page. 13
Buiding Codes
ity assurance requirements. The contractor is defined as the firm the owner engages for the construction of work. The contractor may, in turn, contractually transfer the responsibilities for masonry quality assurance to the masonry subcontractor.
In order to understand the requirements of Table 1, it is necessary to define essential facilities. Essential facilities, for purposes of this table, are defined in ASCE 7, Minimum Design Loads for Buildings and Other Structures, as "buildings and other structures that are intended to remain operational in the event of extreme environmental loading from wind, snow, or earthquakes." Essential facilities specifically include hospitals and other emergency health care facilities; fire, rescue and police stations; emergency shelters; emergency communication facilities; emergency power generating facilities; and facilities having critical national defense functions. All other buildings, such as office buildings, shopping centers, industrial buildings and warehouses, are considered non-essential facilities.
Table 1 shows that a non-essential facility designed empirically, or using veneer or glass block, is guided by the minimum requirements of Inspection Quality Assurance Level 1. Level 1 Quality Assurance requires certificates showing that the materials used in masonry construction are in compliance with the contract documents. This is most commonly accomplished by the manufacturer providing a letter, or certificate of compliance, that the material conforms to the appropriate ASTM Standard, such as a concrete block unit conforming to ASTM C 90, or a common brick unit conforming to ASTM C 62. The minimum inspection requirements mandate that materials comply with approved submittals. Although the Code does not provide guidance on how to accomplish this requirement, a reasonable approach would be to verify that the masonry materials are provided by the same manufacturer. Verification of every delivery to the project would align more with the requirements of Level 3 Quality Assurance.
Essential Facilities that are designed empirically, as well as masonry veneer and glass block contained in an essential facility, and all other masonry that is constructed in a non-essential facility falls under the requirements of Level 2 Quality Assurance. In addition to the simple requirements of Level 1 Quality Assurance, Level 2 states that there shall be a verification of the compressive strength of masonry (f'm) prior to the start of construction. This is actually quite easy using the Unit Strength method of Tables 1 or 2 in ACI 530.1-99. It should be acceptable for a manufacturer to certify the strength of the unit (a test report may be required) and the type of mortar is certified, thereby completing both variables required for the applicable table. Since the table is conservative, the designer should be comfortable of the quality assurance
SPECIFICATIONS FOR MASONRY STRUCTURES
(ACI 530.1-98) Inspection Table Reference
| Type of Masonry | Type of Facility | Quality Assurance |
|---|---|---|
| Empirical Masonry (Chapter 5) | Non-Essential Facility | Level 1 |
| Masonry Veneer (Chapter 6) | Non-Essential Facility | Level 1 |
| Glass Block Masonry (Chapter 7) | Essential Facility | Level 2 |
| All Other Masonry | Non-Essential Facility | Level 2 |
| | Essential Facility | Table 3 |
Table 1
submittals.
Level 2 Quality Assurance inspection requirements are increased from Level 1 Quality Assurance, including verification of proportions of site prepared mortar. With the popularity of factory blended mortar, this requirement will have diminishing impact on the contractor. Inspection of the wall immediately prior to grouting will satisfy mortar joint inspection and location of connectors and reinforcement. For grouted walls, observation of the grouting process is an important step. Proper location of the structural reinforcing steel and proper placement and consolidation of the grout is the bridge between masonry design and successful performance of the masonry. The inspection process also includes casting and caring for masonry prisms when used as the means for verification of the compressive strength of masonry and casting and caring for mortar and grout specimens when they are occasionally required.
As noted above, verification of the compressive strength of masonry by the Unit Strength method satisfies the requirement, thereby eliminating the need to cast prisms. For contractors constructing plain, or unreinforced, masonry, it should be noted that reinforcing steel and grout are not part of the system, therefore, many of the requirements of Level 2 Quality Assurance do not apply.
In addition to the requirements of Level 2 Quality Assurance, Level 3 Quality Assurance increases the inspection requirements in two significant areas. First, the verification of compressive strength of masonry must be done for every 5,000 square feet of wall area, and second, the inspection must be continuous during masonry construction. These requirements apply only to essential facilities, such as hospitals, police and fire stations, disaster shelters and similar structures that are essential for opera-