Product Technical Guides : US-EN Anchor Fastening - August 2021

Anchor Fastening Technical Guide , Edition 22

12 " Brick Bearing Walls

brick ) and C652 ( hollow brick ).

be installed in conjunction with a screen tube to prevent uncontrolled flow of the bonding material . In hollow masonry , anchor strength is generally assumed to be based on the face shell thickness , which can be variable .

CLAY BRICK

Clay brick is the most extensively used type of masonry unit throughout the world . Bricks are prismatic masonry units made from a suitable mixture of soil , clay and a stabilizing agent ( emulsified asphalt ). They are shaped by molding , pressing , or extruding , and are fired at elevated temperature to meet the strength and durability requirements of ASTM C62 ( solid

Depending upon the grade , clay masonry bricks can have a compressive strength ranging from 1,250 to over 25,000 psi . Grouted multi-wythe masonry construction typically consists of two wythes , each one unit masonry in thickness , separated by a space ( collar joint ) 1 / 2 " to 4-1 / 2 " wide , generally filled with grout . The wythes are connected with wall ties . This space may also be reinforced with vertical reinforcing bars . Solid brick masonry consists of abutting wythes interlaced with header courses . In general , chemical anchors are recommended for use in brick . In older unreinforced construction ( URM ), or where the condition of the masonry is unknown , it is advisable to use a screen tube to prevent unrestricted flow of the bonding material into voids .

MORTAR

Mortar is used to provide uniform bearing between masonry units and to bond individual units into a composite assemblage that will withstand the imposed loading conditions . Mortar consists of a mixture of cementitious material , aggregate and water proportionally combined in accordance with ASTM C270 . Cement / lime mortar or masonry mortar ( each in four types ) are typically used under this Standard .

Mortar Type

Average compressive strength at 28 days , minimum psi ( MPa )

Cement-lime M 2500 ( 17.2 ) S 1800 ( 12.4 ) N 750 ( 5.2 )

Since mortar plays a significant role in the structural integrity of a masonry wall , it is important to understand how post installed anchors interact with the structure . Within a masonry structure there are designated joint locations , and the proximity of a post-installed anchor or power-actuated fastener to one of these locations must be considered in the design of the anchorage . Product specific guidelines are provided within this technical guide .

GROUT

ACI defines grout as “ a mixture of cementitious material and water , with or without aggregate , proportioned to produce a pourable consistency without segregation of the constituents ”. The terms grout and mortar are frequently used interchangeably but are , in actuality , not the same . Grout need not contain aggregate ( mortar contains fine aggregate ), is supplied in a pourable consistency ( mortar is not ), and fills voids ( mortar only bonds elements together ).

In summary , grout is used to fill spaces or cavities and provide continuity between building elements . In some applications , grout will act in a structural capacity , such as in unreinforced masonry construction .

Grout , with respect to post-installed anchorages , is specified by the design official . When post-installed anchors are tested for the development of design values , the grout is specified according to applicable ASTM standards . Design engineers are encouraged to become familiar with the characteristics of the grout used in performance testing to better understand the applicability of the design loads published in this guide .

2.1.4 ADMIXTURES

Chemical admixtures are ingredients added to the basic components of concrete or mortar ( cement , water , and aggregates ) immediately before or during mixing . Chemical admixtures are used to enhance the properties of concrete and mortar in the plastic and hardened state . These properties may be modified to increase compressive and flexural strength , decrease permeability and improve durability , inhibit corrosion , reduce shrinkage , accelerate or retard initial set , increase slump and working properties , increase cement efficiency , improve the economy of the mixture , etc .

Testing of post-installed anchors is performed in concrete without admixtures . Designers should take into consideration the effects produced by admixtures on concrete when considering the use of post-installed anchors .

	O	350	( 2.4 )
Masonry cement	M	2500	( 17.2 )
	S	1800	( 12.4 )
	N	750	( 5.2 )
	O	350	( 2.4 )

Product Technical Guides : US-EN Anchor Fastening - August 2021 | Page 15