1 Mortar and grout materials Proportion specification Property
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Mortar and grout materials Proportion specification Property specification Field testing Concrete knowledge does not always apply Stronger mortar is not better Nebraska Concrete Masonry Association January 2011 Masonry Standard Joint Committee (2008) TMS 402‐08/ACI 530/08/ASCE 5‐08 International Building Code (2006, 2009) Chapter 21 References MSJC References MSJC “MSJC” Code Plastic (Unhardened) Mortar Workability Water retention Board life C it Consistency Adhesion www.masonrysociety.org Hardened Mortar Durability Strength Weather protection Look good Look good ASTM C 270 Standard Specification for Mortar for Unit Masonry ASTM C 780 Preconstruction and Construction Evaluation of Masonry Mortars ASTM C 1586 Standard Guide for Quality Assurance of Mortars 1 Cement: main binder Portland cement: ASTM C 150 (Type I, II, III) Historically: Mud Clay Earth/ashes O bl d/ th Ox blood/earth Sand/lime Durability High early strength Bond strength Shrinkage Lime: ASTM C 207, hydrated lime Type S, SA (special) – for mortar Type N, NA (normal) – for plaster Late‐age strength Workability Water retention Portland cement/lime Masonry cement: ASTM C 91 Good workability, convenient, low cost Type N, S, M C t i P tl d Contains Portland cement, fillers, admixtures t fill d i t Air content: 8% to 21% Lower bond strength Restricted use in seismic zones Portland cement/lime Masonry cement Mortar cement: ASTM C 1329 A “new” type of cement Developed for use in seismic zones Air content: 8% min. to 16%, max. Minimum bond strength: 70 to 115 psi Water retention: 70% Mortar Materials Masonry sand: Proper “flow” for mason workability – ASTM C 144 Water – Potable, Potable clean Admixtures? – ASTM C 1384 – Pigments, workability enhancers…. – No chlorides! 2 Now M ASTM C 270 Method 1: Proportion Specification A Pre-1954 S A-1 ingredients, mix design O A-2 A 2 N B W C O D R No laboratory testing required K M a S o N w O r K Type M: 1 portland cement – ¼ lime – 3 ½ sand Type S: 1 portland cement – ½ lime – 4 ½ sand Type N: 1 portland cement – 1 lime – 6 sand T Type O: 1 portland cement – O 1 tl d t 2 lime – 2 li 9 9 sand d Proportions by volume Mortar Type Portland Cement Lime M 1 ¼ S 1 ¼ to ½ N 1 ½ to 1 ¼ O 1 1 ¼ to 2 ½ Sand 2 ¼ to 3 times cement and lime volumes Remember: 1 bag portland cement = 1 cubic foot 1 bag lime = 1 cubic foot (usually) Masonry cement and mortar cement ASTM C 270 Typical Proportions Method 1: Proportion Specification Method 2: Property p y Specification p – minimum strength, water retention, air content – bond strength? Masonry/Mortar Cement Mortar Type M M S S N O M S N Portland Cement Sand 1 1 1 1 1 ½ 2 ¼ to 3 times total cement volume 1 1 Laboratory testing required 3 Preconstruction tests in lab using job site materials Minimum Typical Mortar Type Compressive Compressive Strength (psi) Strength (psi) M 2500 3000 – 3800 S 1800 2300 – 3000 N 750 1500 – 2400 O 350 750 – 1200 Preconstruction tests in lab using job site materials Water Retention – 75% (PCL and MC); 70% Mortar Cement Air Content Air Content, max. % Mortar Type Cement‐Lime Masonry Cement Mortar Cement M, S 12 18 8 to 14 N, O 14 20 8 to 16 High Cement Increased mortar strength Increased mortar durability Increased rigidity Hi h Li High Lime Improved bond Improved watertightness at bondline Unit Unit Note that mortar does not fill irregular surface of unit. Mud is too stiff. Problems: Poor bond and leaky walls Bond strength depends on: Unit Unit Note that mortar completely fills irregular surface of unit. Mud is workable. Results: Good bond and “tight” walls Unit absorption Mortar type Mortar water retention Weather conditions Weather conditions Care in laying units Mortar bond line delamination 4 Inadequate bond Shrinkage cracking (too much cement) Mortar too dry It’s in the mason’s best interest to provide a mortar that has the proper consistency Proper consistency will ensure a “durable” wall Workmanship (quality) has the greatest effect on Strength Bond Water penetration resistance Unit Specify a mortar that the mason can work with Unit Masonry fails in compression by tension splitting of the units ….NOT BECAUSE mortar crushes Large changes in mortar strength do not change prism strength significantly Lateral expansion under compression Consider: Choose your mortar wisely – strength comes at the expense of workability, water retention, weather resistance 1. Plastic properties Easy for mason to use 2 Hardened properties 2. Hardened properties Adequate strength, durability Mortar Type 28‐day Cube Strength (psi) Water Retention Tensile Bond Strength M Very High Low High S High Mod. High N Moderate High Mod. O Low Very High Low 5 Mortar Type Extent of bond Bond durability M Low Very low Permeability in wall tests (leakage) High S High Moderate Moderate N High High Low O Very high Very High Low No single mortar is best for all uses Never use mortar stronger than the units General Rule of Thumb: Choose weakest mortar that satisfies project performance requirements Efflorescence potential? What’s easier to clean? Type N Type S Type O General all-around use Î Exterior walls Î Masonry veneers Î Repointing mortar Î Severe weather exposure: above grade only Î High flexural bond strength Î Reinforced masonry Î Unreinforced masonry: where strength is important Î High seismic zones Î Good durability Severe weather exposure: below grade, retaining walls Î Î Cost effective Î Low strength Î Interior, non-load bearing masonry Î Repointing mortar: pre1890 masonry Type M Very high compressive strength Good durability: Î Below grade walls Î Sewers Î Manholes Î Retaining Fully grouted 8” wall Location Building Segment 52% of the wall volume is grout! Mortar Type Recommended Alternate S N N N S S Exterior, above grade Reinforced, Loadbearing Veneer, Non-loadbearing Parapets, Chimneys Exterior, at or below grade Foundations, Retaining Walls, Paving S M Interior Load-bearing Non-load-bearing N O S N Structural strength Bonds reinforcing bars and units into one structural system Fire resistance Sound resistance Thermal mass 6 Grout – A mixture of cementitious materials and aggregate to which water has been added such that the mixture will flow without segregation of the constituents Can you use mortar in place of grout??? NO!!! Non‐structural masonry – filling cells in a chimney, for instance 1” to 6” 5” to 7” 8” to 11” 12” Concrete Mortar Grout Slump Test Comparison Cement Portland Cement (ASTM C 150) Blended Cement (ASTM C 595) Up to 40% fly ash, ground blast furnace slag Lime Small percentage permitted Pumping aid? ASTM C 404 – Aggregates for Masonry Grout Fine aggregate – sand Coarse aggregate 3/8” chip gravel Larger sizes? Method 1: Proportion Specification Type Fine Coarse Portland or Blended Cement 1 Hydrated Lime or Lime Putty 1 0 to 1/10 0 to 1/10 Aggregate measured in a damp, loose condition Fine (Sand) Coarse (3/8”) 2 ¼ to 3 times cement + lime 2 ¼ to 3 times 1 to 2 times cement + lime cement + lime Typical proportions ÎFine grout: 1 part cement, 3 parts sand ÎCoarse grout: 1 cement, 3 sand, 2 gravel Method 2: Property Specifications Grout Strength 2000 psi minimum strength Min. = ff’m Min. Need not be stronger than unit strength Grout Slump Slump: 8 to 11 inches 7 Engineer: design requires f’m = 1,500 psi What should your grout strength be? 1,500 psi? 2,000 psi? 3,000 psi or more? Coarse grout works best for most applications Less shrinkage Better strength Saves money Grout Clear Space Coarse grout: 24-foot lift, 3” x 4” space required Specifying high strength grout does not give you high strength masonry!!! Leave the choice of grout type up to the mason Low Lift High Lift Up to 5 foot grout pour Grout pour more than 5 feet No cleanouts required Walls gain strength daily No mortar cure time needed but… but Frequent lap splices Frequent grouting More inspection 12’‐8” foot lifts up to 24 foot pour Faster, easier inspection “Self inspecting” for wall ties, workmanship Efficient use of mason labor Efficient use of mason labor MSJC Building Code Requirements for Masonry Structures Section 1.19.1 but… Cleanouts required More wall bracing needed Scheduling grout is critical! Leave the choice of grout lift height up to the mason Self-consolidating grout demonstration panel Building Code requirements ASTM Field vs. lab tests In the past: Too much emphasis on field tests for mortar strength In the future (now) In the future (now): Use lab tests for mortar strength Keep track of mix proportions, batching operations Masonry strength (f’m) by prism tests 8 MSJC Who requires tests? Project Specifications Building Codes Compliance with f’m: Prisms Units Grout Mortar??? Required Tests and Submittals Masonry material certificates Verify f ‘m prior to construction Level A Empirical Design, Veneer, or Glass Unit Masonry Level B Engineered Design Level A Level B Level C • • • • • • • Verify f ‘m during construction (1 test per 5,000 sq. ft.) Verify proportions of materials in mortar, grout, prestressing grout Mortar, grout tests Not required by code!! Level C IBC = = = None Level 1 Level 2 Verify proportions Watch batching and mixing Î Manufacturer’s submittals Method 1: Proportion Specification Quality Control per ASTM C270: Î No “When required…..” follow ASTM methods q f Type M, S, N job site testing required! materials used on job are correct Î Verify material proportions are correct Î Verify Volume of Cement Lime Sand 9 Method 2 Property Specification Quality control per ASTM C270: Testing required to pre‐qualify mortar mix Laboratory methods Property Specifications No job‐site testing required Verify proportions in the field Flow Water retention Air content Compression strength: 2 inch cubes T Type M, M S, S N ASTM C270 can not be used for site testing!!! ASTM C780: Construction evaluation Min. Strength Max. Air Content Min. Water Retention ASTM C 270 only for lab‐prepared mortar ASTM C 780 only for quality control “No correlation between mortar properties and masonry performance” “Results not required to meet requirements of C270” ASTM C 780 2-inch by 4-inch cylinders Mortar sampled direct from mixer Î ASTM C 1586‐04 Standard Guide for Quality Assurance of Mortars “Proper use of ASTM C 270 and C 780” Specify properties or proportions, but not both Do not use C 270 to evaluate site‐produced mortars Using C 780 to determine compliance with C 270 compressive strength requirements is not appropriate More water = lower strength Whether using proportion or property method - there are specified proportions that must be used. So - verify those proportions are being used. • Visual observation • Mortar Aggregate Ratio test Monitor mortar proportions on site How do you feel about shovel counts? 10 Proportions Fine grout 1 cement : 3 sand (typical) Coarse grout 1 cement : 3 sand : 2 gravel (typical) Aggregate size 3/8 3/8” max. max size Aggregate size Slump 8 to 11 inches Grout Specifications ASTM C 476 Slump: 8 to 11 inches Min. strength: 2,000 psi Grout Test Method Grout Test Method ASTM C 1019 High Slump Grout High initial water/cement ratio Water absorbed by units Final w/c ratio ~ 0.45 ASTM C 1019 The Masonry Society www.masonrysociety.org Brick Institute of America www.brickinfo.org National Concrete Masonry Association www ncma org www.ncma.org Portland Cement Association www.cement.org . masonrysystems.org Design ideas Technical information Cost calculator Atkinson-Noland & Associates, Inc.* 10/06/97 www.ana-usa.com Boulder, Colorado 303-444-3620 1 11
