1.0 WHAT IS CHANGING ?
For many years , post-installed adhesive and mechanical anchors have been utilized for fastenings into masonry base materials . While the relevant model design codes ( i . e ., ACI and CSA ) for post-installed anchors into concrete base materials have evolved , the relevant model design codes for post-installed anchors into masonry base materials have remained unchanged for decades . In recent years , testing and evaluation criteria for post-installed adhesive and mechanical anchors in masonry base materials have been based on three International Code Council Evaluation Services ( ICC-ES ) Acceptance Criteria : AC01 for Expansion Anchors in Masonry Elements , AC106 for Predrilled Fasteners ( Screw Anchors ) in Masonry Elements , and AC58 for Adhesive Anchors in Masonry Elements . In 2020 , these three criteria were considerably revised with a compliance date of April 15th , 2023 , assigned to adhesive anchors and February 16th , 2024 , assigned to mechanical anchors . Some of the changes include but are not limited to :
• The consolidation of AC106 into AC01 to create one Acceptance Criteria for all mechanical anchors installed into masonry base materials .
• The clarification of the types of masonry systems included in AC01 and AC58 such as : fully grouted concrete masonry units ( CMU ), partially grouted CMU , ungrouted CMU , and clay brick .
• The adoption and adaptation of ACI 318 ’ s Concrete Capacity Design ( CCD ) method for the design of postinstalled anchors into masonry base materials .
• The inclusion of cracked masonry testing and evaluation .
The Masonry Anchor Strength Design Guide is intended to present these industry changes to post-installation of adhesive and mechanical anchors into masonry base materials in a simplified and easy-to-understand format . The guide will start with discussion on common masonry definitions as well as the updated clarification of the types of masonry systems . The design of post-installed anchors into masonry base materials will closely mirror the design of post-installed anchors into concrete base materials per ACI 318 Chapter 17 . The guide will discuss the similarities and the differences between concrete and masonry design . Additionally , common design considerations and design examples will be shown to demonstrate the overall design process .
Following the discussion on the changes to the testing and evaluation criteria , the Masonry Anchor Strength Design Guide will provide technical data for the various Hilti postinstalled adhesive and mechanical anchors approved for anchoring into masonry base materials . Additionally , Hilti ’ s PROFIS Engineering software can be utilized for postinstalled masonry anchor design .
2.0 WHAT IS MASONRY ?
Masonry is a heterogeneous building material usually consisting of concrete masonry units ( CMU ) or clay brick bonded together using joint mortar . The primary application for masonry is the construction of walls , which are built by placing masonry components in horizontal rows ( courses ) and / or vertical rows ( wythes ). The horizontal mortar joint between two courses of masonry units is referred to as the bed joint . The vertical mortar joint between two masonry units in the same course and wythe is referred to as the head joint . The head joint in CMU construction employing closed-ended units ( e . g ., hollow concrete block ) is referred to as a hollow head joint . The head joint in CMU construction employing open-ended units ( including lintel or bond beam ) will allow grout to be placed in the head joint area and is referred to as a solid head joint .
Masonry components can be manufactured in a wide variety of shapes , sizes , materials , and both hollow and solid configurations . These variations require that the selection of an anchoring system be carefully matched to the application and type of masonry material being used . As a base material , masonry typically has a much lower strength than concrete . The behavior of the masonry components , as well as the geometry of their cavities and webs , has a considerable influence on the load capacity of the fastening .
When drilling holes for anchors in masonry with hollow cavities , care must be taken to avoid spalling on the inside of the face shell . This could greatly affect the performance of “ toggle ” type mechanical anchors whose length must be matched to the face shell thickness . To reduce the potential for spalling , unless otherwise specified , holes should be drilled with hammer drills set in rotation only mode ( i . e ., hammering action of the drill turned off ).
CONCRETE BLOCK
Concrete block is the term commonly used to refer to concrete masonry units ( CMU ) made from Portland cement , water , and mineral aggregates . CMU blocks are manufactured in a variety of shapes and sizes using light , medium , and normal weight aggregates . Both hollow and solid load bearing CMUs are manufactured in accordance with ASTM C90 .
CMU sizes generally refer to the nominal width of the unit ( e . g ., 6 ”, 8 ”, 10 ”, etc .). Actual dimensions are nominal dimensions reduced by the thickness of the mortar joint .
2 Masonry Fastening Technical Guide Edition 24 Hilti , Inc . 1-800-879-8000 | en español 1-800-879-5000 | www . hilti . com | Hilti ( Canada ) Corporation | www . hilti . ca | 1-800-363-4458