CMAA CM01 Concrete Masonry Handbook - Donuts
CM01Concrete Masonry Hand Book
While the contents of this publication are believed to beaccurate and complete, the information given is intended forgeneral guidance and does not replace the services ofprofessional advisers on specific projects. ConcreteMasonry Association of Australia cannot accept any liabilitywhatsoever regarding the contents of this publication.Copyright Concrete Masonry Association of Australia2014.ABN 33 065 618 804.This publication, its contents and format are copyright of theConcrete Masonry Association of Australia, and may not bereproduced, copied or stored in any medium without prior,written authorisation from the Institute. Concrete MasonryAssociation of Australia is wholly sponsored by theAustralian concrete brick, block and paver industry. Local orstate regulations may require variation from the practicesand recommendations contained in this publication.Revised and Republished 2014.The Standards referenced in this manual were current at thetime of publication.Product: Austral Masonry GB Honed PO Box 370, Artarmon NSW 1570 AustraliaSuite 3.02, Level 3, 44 Hampden Road Artarmon NSW 2064 AustraliaTelephone 61 2 8448 5500 Fax 61 2 9411 3801ABN 30003873309www.cmaa.com.au
Concrete Masonry Handbook(Click this to return to Contents)Contents(Click on title to go to subject)1Principal Differences between Blockwork and Brickwork12Block Coding System23Mortar and Mortar Joints64Corner Bonding85Engaged Piers96Modular Planning107Estimating Data148Control Joints149Articulated Designs (or Panel Construction)1610 Finishes and Treatments of Concrete Masonry Walls1711 Applications for Renforced Blockwork1812 Grout Filling2013 The 200 mm Single-Leaf Masonry System – How it Works2114 Single-Leaf Masonry Estimating Worksheet2415 Cleaning of Masonry2616 Australian Standards and Building Code of Australia27Disclaimer: The Concrete Masonry Association of Australia Limited is a non-profit organisation sponsored by the concrete masonry industry inAustralia to provide information on the many uses of concrete masonry products. Since the information provided is intended for general guidanceonly and in no way replaces the service of professional consultants on particular projects, no liability can be accepted by the Association for its use.Remember, when working with cement and concrete/mortar or manufactured or prefabricated concrete products, ALWAYS follow the manufacturer'sinstructions and seek advice about working safely with the products from the manufacturer, your nearest WorkCover Authority or Worksafe Australia.2
Concrete Masonry Handbook1PrincipalDifferencesbetweenBlockwork andBrickworkMasonry is the word used to describe walls built outof masonry units laid on a mortar bed.Masonry Units are commonly called: Blocks (which are generally large hollow units)and;3 Courses, containing 41/2 blocksBricks (which are smaller units, either solid orwith small cores).The masonry built with these units is generallyreferred to as blockwork and brickwork.There are many differences between these twoforms of masonry units and the way they aregenerally used.1.1SizeThe Block most commonly used is hollow and isoften referred to by its nominal size i.e., 400 mmlong, 200 mm wide and 200 mm high. Because anallowance is made for 10 mm wide mortar joints, theactual size of the block is 390 mm x 190 mm x 190mm. To avoid the need for cutting, 3 4, 1 2 and 1 4 lengthblocks are made which are called specials. Otherspecials are made to form lintels, control joints etc.7 Courses, containing 171/2 bricksFigure 1 Number of blocks and bricks in a 600-mmbuilding moduleThe range of blocks with a Nominal width of 200 mmis referred to as the 200 mm Series. Less commonlyused blocks are the 100 mm, 120 mm, 150 mm and300 mm series. Some blocks in the 100 mm seriesare solid. Note that a building module 600 mm x600 mm contains three courses of 11 2 blocks 41 2blocks, see Figure 1.1.3Bricks are usually solid or cored and generally madeto a traditional size, 230 mm long, 110 mm wide and76 mm high. These are the actual dimensions andnominal sizes are not quoted for bricks. It shouldbe noted however that allowing for 10 mm joints, abuilding module 600 mm x 600 mm contains sevencourses of 21 2 bricks 171 2 bricks, see Figure 1.1.2MortarThe sand used in making the mortar used forblockwork should not be the same as commonlyused in mortar for brickwork. "Brickies loam"contains clay particles which make the mortarmore workable, but also causes high shrinkagein the mortar. Clay masonry units tend to expand,which compensates for the shrinkage in the mortar.Concrete masonry units shrink, so that if they areused with a mortar with high shrinkage, crackingmay result.For this reason, the sand used in mortar for concreteblockwork should be clean sharp sand, such asclean pit sand, masonry sand or plasterer’s sand.Tests have shown that the sand can contain upto 10% fines but it should not contain any clayparticles. (See Clause 3 Mortar and Mortar Joints)Material and DimensionalVariationBlocks are generally made of concrete. Becausethey are formed in steel moulds and the material isrelatively stable, the size of individual units can becontrolled to within small tolerances.1.4Bricks are often made of clay. They can undergoshape changes during manufacture, particularlyin the firing process, and individual units can varyconsiderably in size. Tolerances are measuredby placing 20 units together, which measures theaverage size, but not the variation of individualunits.Mortar JointsHollow blocks are normally laid with face shellbedding ie, there are two strips of mortar which arelaid over the face shells with no mortar being laid onthe web. These two strips of mortar are continuedup the vertical (or perpend) joints.Bricks are laid on a full bed of mortar and with a fullperpend.(See Clause 3 Mortar and Mortar Joints)1
Concrete Masonry Handbook1.52Control JointsBecause there is some shrinkage in a concretemasonry wall after it is constructed, it is necessaryto provide control joints in blockwork to preventcracking due to that shrinkage.Because of the wide range of block sizes and"specials" produced, the Concrete MasonryAssociation of Australia (CMAA) introduced acommon coding system. Although there are somevariations between companies you can order aparticular size and shape of block by the same codenumber.Control joints are required in clay masonry to allowfor the expansion of clay and they are referred toas expansion joints. It is most important that thesejoints be thoroughly cleaned out and be sufficientwidth so that they allow the bricks to expand freely.(See Clause 8 Control Joints)1.6Block CodingSystemThe principle of the system is that the first twonumbers of the code number refer to the width ofthe block ie, 20.01 is in the 200 series (200 mmnominal width) and 15.02 is in the 150 series(150 mm nominal width).Grout filling andReinforcementBecause concrete blocks are hollow and the coresare large, it is possible to pour grout (ie, fluidconcrete) into them. When reinforcing rods are alsoplaced in the cores, the resulting combination ofblock grout reinforcement is called "reinforcedmasonry".The numbers following after the full stop refer to thelength on other special features of the block. Thus,in the above examples;20.01 is a standard block (400 mm nominal length)15.02 is a 3 4 length block (300 mm nominal length)Reinforced masonry is very much stronger thannormal masonry in its resistance to bending and itis widely used for the construction of large externalwall panels, lintels, retaining walls, swimming poolsetc. (See Clause 13 Grout Filling)Other examples of the code system are:20.03 is a 1 2 length block20.04 is a 1 4 length block20.12 is a lintel block20.20 is a knock-out bond beam blockThese are all blocks in common usage and generallyavailable everywhere. However, while the codingsystem is the same in all areas, the range of blocksavailable "ex-stock" is not necessarily the samebecause of different local building techniques. Therange of blocks generally available are illustratedon the following pages. Availability of block typesshould always be checked. The range of blockwidths is illustrated in Figure 2.The 200 series block is by far the most commonlyused and the 20.01 represents well over half oftotal block usage. The Series is used principallyfor single-leaf external walls and retaining walls.Most houses in North Queensland are built with200 series blockwork. In most cases 200 seriesblockwork is reinforced.Figure 2 Range of standard block widths2
Concrete Masonry Handbook100 mm series120 mm series150 mm series3
Concrete Masonry Handbook150 mm continuedNOTEThe blocks shownon these pagesare for illustrationpurpose only and notnecessarily availableat all locations.15.73945 SQUINT200 mm le 'u' retainingwall block20.10CONTROL JOINTHALF20.21corner bondBEAM20.56pilaster420.23jamb - full length20.24jamb - half20.57pilaster with controljoint
Concrete Masonry Handbook200 mm CONTINUED20.12220.126three quarterthree-quarter lintel20.120knock-out bond beamRETURN CORNER300 mm SERIES30.01standard520.142channel
Concrete Masonry Handbook3Mortar and MortarJoints3.1MortarThe three principal functions of mortar are: To provide an even bedding for the blocks andallow course levels by taking up small variationsin unit height. To transmit compressive loads. To hold the blocks together in the wall by bondingto them, so that tensile and shear forces canbe carried. (This is often referred to as a "bondstrength"). This is particularly important so thatunits on top of a wall are not easily dislodged.In order to provide a good bond between the unitsand the mortar, the following guidelines should befollowed: An appropriate mortar mix design should beselected, see Table 1. The mortar should be batched accurately usingsome consistent form of volume measurement. The sand used in the mortar should be clean pitsand, masonry sand or plasterer's sand. Clayeyloam or sand containing organic impurities willaffect the mortar strength and should not beused. Mortar should be discarded and not retempered,after the initial set of the cement has taken place. Admixtures. Caution should be exercised whenusing plasticisers or workability agents. Theyshould only be used if specified by the architector engineer and then strictly in accordance withmanufacturer's instructions. Detergent shouldnever be used.Table 1 Mortar types and mixesMortar GP Portland or Building Sand MethylTypeGB BlendedLimeCelluloseCement addedNote 1Where UsedM3M4116OptionalGeneral purpose application with moderate exposure including:105Yes-10.54.5OptionalHigh durability applications with severe exposure including:104Yes-All general purpose blockwork above the DPC.Below the DPC in non-aggresive soils.Greater than 100 m from non surf coastGreater than 1 km from surf coastBlockwork standing in fresh water or non-saline wetting and drying.Fireplaces, barbecues and incineratorsBelow DPC in aggressive soils.Severe marine environment up to 100 m from a non-surf coast.Severe marine environment up to 1 km from a surf coast.B lockwork standing in saline or contaminated water including tidaland splash zones.-B lockwork within 1 km of an industry in which chemical pollutantsare produced.Notes:1 Methyl Cellulose water thickener is used to prevent the rapid drying out of the mortar thus improving its workability as well as increasing bondstrength. It does not have the detrimental effect of the plasticisers. It is available under the trade name of DYNEX or similar.2While this table provides an overall general guide to where mortar is used, the Australian Standard for Masonry Structures AS 3700 has detailedspecific requirements for where both the mortar and masonry units can be used.6
Concrete Masonry Handbook3.2Mortar JointsThe mortar bed on both horizontal joints andperpends extends only for the width of the faceshell. Most blocks have a tapered core and are laidwith wider part of face shell to the top. (SeeFigure 6)Joint FinishingThe preferred finish for mortar joints in faceblockwork is an ironed finish. (See Figure 6)Figure 4 Mortar applied to the perpendsThis finish is obtained by ironing the joints with anironing tool when the mortar is firm to the touch(about 20-30 minutes after laying) and then lightlyscraping off the surplus mortar with the trowel, or bylightly brushing. (See Figure 5)The ironing tool should be made of 12 mm diameterround rod and be more than 400 mm long to ensurethat a straight joint is produced.The reasons that the ironed finish is preferred are: The ironing tool compresses the mortar at theface of the masonry and thus makes it denserand more durable. The mortar is pushed against the top and bottomfaces of the blocks, thus improving the bondbetween the mortar and the block where itmatters most.Figure 5 Ironing the joints with an ironing toolHowever, where a plaster or textured coating is tobe applied to the blockwork, a flush joint may beused. This may be produced by rubbing the surfacewith a piece of block when the mortar is firm toprovide a flat surface under the coating. (SeeFigure 7)Also, a 3–5 mm raked joint can be used as an aid toforming a key for solid render. (See Figure 8)Raked joints should never be used with hollowblocks, which are not to be rendered because: The width of face shell mortar would be reduced. The weatherproofing would be adverselyaffected.Figure 6 Ironed finish (face-shell cross section)Note:Raked joints are used in face brickwork for aestheticreasons.Figure 7 Flush finish (face-shell cross section)Figure 3 Mortar applied to the face-shellsFigure 8 Raked finish with render7
Concrete Masonry Handbook4Corner BondingFigure 9 Typical hollow-block corner detailsFigure 10 Typical split-block corner details8
Concrete Masonry Handbook5Engaged PiersFigure 11 Pier at end of 100 mm split-block wallFigure 12 Pier at end of 100 mm hollow-block wallFigure 13 Engaged pier in 100 mm hollow-block wall9
Concrete Masonry Handbook6Modular PlanningThe concrete block was one of the first buildingcomponents to be designed with modularconstruction in mind. Originally it was based on a100 mm module (it remains 4" in the USA) but whenthe metric system was adopted in Australia duringthe 1970s, this was changed to a 300 mm module.Providing the design of a building is based on thismodule, no cutting of blocks is required. Since mostother building materials are now supplied in sizesthat are multiples of 100 mm, this is generally not aproblem. The preferred height dimensions are basedon this module. See Figure 14.Nominal widths of doors and windows are alsobased on this module eg;900 mm wide single door,1200 mm, 1800 mm 2400 mm windows and doors.Figure 14 Vertical modular dimensions10
Concrete Masonry HandbookThe preferred way of dimensioning drawings is toshow these nominal sizes on openings, as shown inFigure 15.However, because the blocks are made 10 mmshorter than the nominal (or modular) size, theactual openings will be as shown in Figure 16.For this reason, window and door frames aremanufactured to suit openings which are 10 mmwider than the module eg. 910 mm, 1210 mm,1810 mm, 2410 mm.The length of piers and walls are also 10 mm lessthan the modules ie, 890 mm, 1790 mm etc.200 mm ModuleIt is recommended to plan a building using a200 mm or 400 mm module, as significant reductionin the number of “special” blocks is achieved. Also,the cores in the blocks line up for grout filling.Figure 15 Preferred method of dimensioning drawings using the nominal sizes of openingsFigure 16 The equivalent actual size of openings11
Concrete Masonry HandbookPlanning grid showing 200 mm x 400 mm block elevations at approximately 1:50 scale12
Concrete Masonry HandbookPlanning grid showing 200 mm x 200 mm block plan at approximately 1:50 scale13
Concrete Masonry Handbook7Estimating Data8Control JointsBlocksThere are 121 2 blocks in every square metre of wallsurface area.Control Joints are provided in masonry walls in orderto prevent cracks appearing. These cracks can becaused by various movements such as:Mortar1m3 of mortar is required for approximately 800blocks. Shrinkage of concrete masonry units(or expansion of clay masonry units). Temperature movements.For a 1:1:6 mortar mix, the approximate quantitiesrequired for 1m3 of mortar are: Differential settlement of footings (Figure 17).Hogging support. Top tension cracking. anddiagonal cracking is likely to occur.6 bags cement6 bags lime1.2m3of damp sand (allowing 20% bulking)GroutApproximate quantities for filling concrete blocksand elements:BlocksRequired volume (m3) perm2 of wall100 blocksNumber blocksper m3 of 5020.480.1000.8012030.480.1801.4469ElementRequired volume (m3) per linear m200 mm wall – isolated core0.020200 x 200 mm bond beam (20.20)0.025200 x 400 mm lintel0.042Sagging or dishing support. Friction at thebase may stop the tension cracking.Diagonal cracking still likely to occur.In unreinforced 90 mm and 110 mm thick walls(including veneer and cavity construction) controljoints should be spaced at all poits of weakness,and not more than 6 m apart.In unreinforced walls of 140 mm and 190 mmthickness the inclusion of horizontal bond beams isrecommended. In this case the spacing of controljoints may be increased up to a maximum of 8 m.The more vertical cores that are filled with groutand reinforcement the greater will be the control ofcracking.Unreinforced Masonry ConstructionControl joints should be built into unreinforcedconcrete masonry at all joints of potential crackingand at the locations shown on the drawings, butin no case greater than 6-m spacing in articulatedresidential construction and 8-m spacing in otherconstruction.Reinforced Masonry ConstructionControl joints should be built into reinforcedconcrete masonry at all points of potential crackingand at the locations shown on the drawings.In reinforced masonry walls over 3 m high, thespacing of control joints should not exceed 16 m. Inreinforced masonry walls 3 m or less in height, andincorporating a reinforced bond beam at the top, thecontrol joints may be deleted.Figure 17 Dfferential settlement of footings1414
Concrete Masonry HandbookControl Joints should always be provided at thefollowing locations: At major changes in wall height. At changes in wall thickness (other than at piers). At control joints in floor and roof slabs. At T-junctions.In straight walls, they may be formed with specialcontrol joint blocks (20.09 and 20.10), seeFigure 19.Figure 20 Control joint detail in a bond beamThis detail relies on the reinforcement in the bondbeam to provide the shear transfer across the jointFigure 18 Typical control joint at a pilasterFigure 19 Typical control joint within a wall15
Concrete Masonry Handbook9ArticulatedDesigns (or PanelConstruction)Articulated Masonry Construction – What Is It?This is the system which eliminates the stressconcentrations caused by corners and openings,breaking the masonry by jointing, into separatepieces or panels which allows for relative movement.The technique of breaking masonry construction intoseparate rectangles joined by panels which allowrelative movement is called “Articulation”.Rectangular panels are vastly stronger than panelswith openings and are much less likely to formcracks.The fundamental principle of articulation is toprovide allowances in the form of control jointswhich allow for anticipated relative movement.Figure 24 shows the way in which an articulatedwall would behave when subjected to distortions insupporting members.The use of articulation is normally confined tounreinforced cavity and veneer construction anddoes not apply to partially or fully reinforced walls.Figure 22 Consequences of distortions of supportsof walls with openingsFigure 23 Typical articulated wallFigure 24 Behaviour of articulated wall after distortionof supporting members16
Concrete Masonry Handbook10 Finishes andTreatments ofConcrete MasonryWalls10.1 Finishes to External WallsExternal walls may be finished in a variety of ways,including: Face blockwork Bagging and painting Rendering and painting Painting Textured finishesWhere the wall is to be face blockwork, particularcare is required in achieving a high standard of jointfinish.10.3 Surface PreparationWhether or not an external treatment is to beapplied to the walls, it is essential that all mortarjoints be filled to the depth of the face shells andironed, the mortar being compressed with an ironingtool slightly larger than the joint, leaving no voids.Particular care is needed to ensure joints underwindow sills are properly filled. On completion, theexternal face of the wall should be inspected andany faulty mortar joints or surface defects in blocksshould be repaired with a 3:1 sand/cement mixture.On completion the wall needs to be rubbed downwith either a piece of block or carborundum stoneto remove any excess material. If the wall is notnew, accumulations of dirt, dust, oil or efflorescencemust be removed by scrubbing, brushing (withappropriate solvents if necessary) and hosing.Generally, existing paint films must be removed.Check with your paint supplier before applying newpaint over old paint.Cavity and Veneer ConstructionIt is not essential to provide an external finish tothese types of walls. Should a more decorative finishbe required, there are special blocks that can beused eg, plain or coloured split blocks. Alternatively,a large range of decorative treatments can beused including 100% acrylic-based paint, rolled ontexture paint and applied texture treatments.Control JointsSurface treatments, other than paint, should notbe continued across control joints but should bescribed to allow for movement. These joints mustbe sealed to prevent water penetration. A typicalcontrol joint detail is shown in Figure 25.Joint sealants should be applied towards the endof construction to minimise the effect of panelmovement.10.2 Finishes to Internal WallsFigure 25 Control joint detailInternal walls may be finished in a variety of ways,including:10.4 Special requirements forSinge-leaf masonry System Face blockwork Bagging and painting Adhesive-fixed plasterboard Rendering and painting10.4.1 General Wallpapering Painting Textured finishesTo prevent water penetration, it is essential thatsingle leaf skin walls have a reliable weatherprooffinish or treatment applied, the recommendedprocedures are as follows (see also Figure 26):Where the wall is to be face blockwork, particularcare is required in achieving a high standard of jointfinish. Surface preparation should be as describedin Clause 10.3. When these procedures arefollowed, an economical and very acceptable finishcan be achieved. Weatherproof all of the external wall, includingwindow reveals, before the windows are fixed(see Clause 10.4.2). Fix windows with Ramset ED642 anchors, orequivalent. Before the anchor is inserted, the holeshould be filled with sealant. Seal the whole perimeter of the window on theinside and to the head and jambs only of theperimeter on the outside with Sikaflex 15LM orequivalent. The use of sash groove blocks is notrecommended.17
Concrete Masonry Handbook Door frames are to be fixed and sealed inaccordance with the above, except that theanchors should be Ramset ED655 or equivalent.10.4.2 Weatherproof TreatmentsApplication of PaintTwo alternative treatments are recommended: Three coats of 100% acrylic-based exteriorquality gloss paint (eg, Wattyl Solagard, DuluxWeathershield, Taubmans All Weather Gloss)applied by brush or roller. One complete coat of cement-based paint(eg, Silasec) followed by two finishing coats of100% acrylic-based exterior-quality gloss paint,applied by brush or roller.Whichever of these two treatments is used, it isessential that: The manufacturer’s instructions are followed,particularly with regard to coverage rate. All of the external wall is weatherproofed,including window reveals. This entails fixingmeter boxes, down pipes, windows etc, after thepaint treatment is complete.11 Applications forReinforcedBlockworkReinforced blockwork is used in a great variety ofstructures. Technical brochures are available fromCMAA Member Companies on a number of differentapplications including Retaining Walls, Housing,Industrial Buildings, Swimming Pools, Fences etc.Samples of the type of information provided in thesebrochures include retaining wall construction(Figure 27) and single-leaf wall construction system(Figure 28).Single-leaf walling system is used for theconstruction of most houses in North Queenslandand is widely used in Central Queensland. It is asimple system which is suitable for housing in areasof design wind speeds from N2 to C4 in cyclonicand non-cyclonic areas.Other CoatingsAlternatively there are other stylish texture finishesincorporating elastic polymers which can enhancethe aesthetics of the walls and at the same timeproviding satisfactory weatherproofing. It is essentialthat the texture coating incorporates a waterproofingmembrane.Clear CoatingsClear coating are not recommended.WeatherproofcoatingLintel beamRamset anchorsor equivalentRECOMMENDED PROCEDUREWeatherproofcoating1 Weatherproof all of the external wall, includingwindow reveals, before the windows are fixedRamset anchorsor equivalent2 Fix windows with Ramset ED642 anchors, orequivalent. Before the anchor is inserted, thehole should be filled with sealantSealant each sideof window frame3 Seal the whole perimeter of the window frameon the inside and the jamb and head sections onthe outside, with Sikaflex 15LM or equivalentHEAD FIXINGRamset anchorsor equivalentApply weatherproofcoating to all of theopening surroundbefore windowsare fixed intopositionRamset anchorsor equivalentSill unitBond beamWeatherproofcoatingWeatherproofcoating4 Door frames are to be fixed and sealed as setout for windows, except the anchors should beRamset ED655 or equivalent.Ramset anchorsor equivalentSealant each sideof window frameJAMB FIXINGSealant on insideSill flap on outsideRamset anchorsor equivalentWeatherproofcoatingSILL FIXINGFigure 26 Weatherproofing and fixing of windows in single-skin masonry construction18
Concrete Masonry HandbookFace-shell bedding only(not on cross webs)Grout hopperFigue 27 Typical construction details for reinforced blockwork retaining wallFigue 28 Typical construction details for reinforced single-leaf masonry walling system19
Concrete Masonry Handbook12 Grout Filling12.1 IntroductionThe large cores in a block, which make it a hollowunit, have two principal advantages: The individual units are lighter to handle. The blockwork can be filled with grout.Because of the high pressures developed at thebottom of the cores when they are filled, groutingin lifts of more than three metres should not beattempted in one pour. Where the lift is more than2.4 metres, it is preferable to fill the cores in twostages about 30 minutes apart.Grout means highly-workable concrete which can bepoured or pumped into small spaces, such as thecores of blocks.By placing reinforcement in the cores before thegrout is placed, the masonry becomes a compositeof block, grout and reinforcement which has astrength similar to that of reinforced concrete.Most masonry walls built out of 150 or 200 seriesblocks have some parts which are grouted andreinforced, typically a bond beam in the top courseand sometimes the end vertical cores.The cores should not be filled with just a sloppymortar but with a correctly designed grout to thefollowing specification.12.2 Grout SpecificationThe grout used to fill the cores or blockwork wallsshould be specified as follows: Characteristic Compressive Strength minimum12 MPa, preferably 20 MPa. Cement content not less than 300 kg/m3. Coarse aggregate of 10 mm. It should have a pouring consistency whichensures that the cores are completely filled andthe reinforcement completely surrounded withoutsegregation of the constituents.12.3 GroutingGrout may be mixed on site and poured frombuckets into hoppers placed on top of the wall.Alternatively, for larger jobs, the grout may bedelivered by transit mixer and pumped into thecores, using a small nozzle on the hose.Before commencing placement of the grout, it isimportant that the cores should be clean and free ofmortar “dags” projecting into the core. A “clean-out”opening is normally provided so that these “dags”can be knocked off by a steel rod pushed down thecore. These are then cleaned out from the bottomof the core before the “clean-out” space is sealed.An alternative method which may be used in somecircumstances is to leave a mortar joint unfilled atthe bottom of the core and to hose the mortar out ofthe core before it has set.In hot weather it may be necessary to hose thecores out with water in order to cool the blocks andso prevent “flash setting” of the grout. If so, thishosing should be completed at least 30 minutesbefore the grout is placed.20
Concrete Masonry Handbook13 The 200 mmSingle-LeafMasonry System –How it WorksStage 1Reinforcement in the form of N12 starter bars iseither placed and tied prior to pouring, to minimisemovement, or placed in the footings immediatelyafter the footing concrete is poured. They arehooked at the bottom to pass under the trench meshin the bottom of the footing and are long enough toproject at least 450 mm above floor level(Figure 29).They are placed at the building corners, on eachside of each door and window opening and at amaximum spacing of 1800 mm* centres between.Their positions are marked on a plan givingdistances from the corners for easy setting out.Figure 29*Reduction will depend on cyclonic category.Stage 2Standard 20.01 blocks are used in the footings up toone course below floor level. 20.20 knock-out blocksare used at floor level with the upper sections ofboth the webs and the in
Concrete Masonry andoo 1 1 Principal Differences between Blockwork and Brickwork Masonry is the word used to describe walls built out of masonry units laid on a mortar bed. Masonry Units are commonly called: ksBloc (which are generally large hollow units) and; icks Br (which are smaller units, either solid or with small cores).File Size: 634KB
Apr 02, 2021 · DUCTR IPTATI GUID 2021 Assessment Technologies Institute , Inc. PAGE 3 CErTIfIEd MEdICAL AdMInIsTrATIvE AssIsTAnT (CMAA) Description The goal of the Certified Medical Administrative Assistant (CMAA) Learning Package 2.0 is to provide directed preparation for the CMAA certification exam* and to ins
CMAA does not provide: design guidance, design critique, advice, comments on non-CMAA documents, etc. Inquiries of this nature, if received, will be declined. Send all written requests for interpretation of CMAA Specifications, identifying the particular Specification and the Section
Masonry lintel design is a critical part of an efficient structural masonry solution. The design of masonry . Figure 2: Steel lintel at bearing Figure 3: Masonry lintel intersection masonry jamb. 2020. Lintel design criteria for all tables below: - Masonry design is based on f'm 2500 psi, strength design, and is designed using NCMA .
Strength design of reinforced masonry beams follows the same steps used for reinforced concrete beams. Strain in the masonry is assumed to have a maximum useful value of 0.0025 for concrete masonry and 0.0035 for clay masonry [Sec. 3.3.2 (c)]. Tension reinforcement is assumed to be somewhere on the yield plateau.
Home Walls Masonry Walls Roof-to-Masonry-Wall Connections Roof-to-Masonry-Wall Connections In older houses with masonry walls it is common to find a 2x8 lumber plate that is bolted or strapped flat like a plate to the top of the masonry wall. The trusses or rafters are then connected to this plate. In older homes the connection may be
masonry school, it would have been a major issue for tilt-up construction. Masonry adapts well to almost any terrain while tilt-up requires a flat surface and sometimes considerable in-fill. Still, there was probably additional site work that would have increased the masonry school cost. (2) The masonry school had a greater window area.
retrofitting an existing masonry wall for increased loads. Masonry Properties: Shear and flexural masonry strength is dependent on the specified compressive strength (f'm) of the existing masonry assembly. The value of f'm, in turn, is dependent on the combination of the net compressive strength of the masonry units and the mortar type.
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