Mortar + Grout Selection Reference

Why this matters

Mortar bonds masonry; grout fills tile + masonry joints; concrete creates structures. Wrong type for application = failed bond OR cracking. The tech who knows the basics handles common service work confidently. This is the field card.

Mortar types (ASTM C270)

Type M (high strength): 2,500 PSI; below-grade, foundations, retaining walls.

Type S (medium-high): 1,800 PSI; below + above grade; chimneys, parapets.

Type N (medium): 750 PSI; above-grade walls; standard residential.

Type O (low): 350 PSI; interior non-load-bearing; historic restoration.

Type K (very low): 75 PSI; historic preservation only; rarely current use.

Mortar mix proportions (by volume)

Pre-mixed bags (Sakrete, Quikrete): just add water + mix.

Sand specification: ASTM C144 masonry sand.

Lime: hydrated; provides workability + bond.

Mortar use by application

Brick / block walls: Type N (most common).

Below-grade / load-bearing: Type S OR M.

Chimney + flue: Type N OR S.

Stone veneer: Type N OR S.

Glass block: Type N.

Tuck-pointing repair: match existing OR Type O / N.

Tile setting: thinset mortar (different category; see below).

Concrete vs mortar

Concrete: cement + aggregate (sand + gravel) + water; structural.

Mortar: cement + sand + lime + water; binds masonry units.

Stucco: similar to mortar; 3-coat application.

Grout (tile): cement + sand (sometimes) + water + pigment; fills tile joints.

Thinset (tile): cement + sand + polymer; bonds tile to substrate.

Concrete mix designs

Standard residential: 3,000 PSI 28-day strength.

Driveway / sidewalk: 4,000 PSI.

Footings: 3,000 - 4,000 PSI.

Foundation walls: 3,000 - 4,000 PSI.

Cold-weather pour: 4,000+ PSI; accelerator additive.

Slump test: 3 - 5" slump typical residential; lower for footings; higher for vertical pours.

Air-entrained: 5 - 7% entrained air; freeze-thaw protection.

Concrete mix proportions

Standard 3,000 PSI residential:

• 1 part cement
• 2 - 3 parts sand
• 3 - 4 parts gravel / aggregate
• 0.5 - 0.6 water-cement ratio

Bag concrete: Quikrete 5000 (5,000 PSI rapid set), Sakrete (3,000 - 5,000 PSI), Premix (lower-strength).

Yards per project: 27 cu ft per yard.

Concrete additives

Plasticizer / superplasticizer: improves workability without adding water.

Accelerator: speeds up cure; cold weather; CalciumChloride (corrodes rebar; use cautiously).

Retarder: slows cure; hot weather + large pour.

Air-entrainer: small bubbles for freeze-thaw protection.

Color: integral OR surface application.

Waterproofing: additive for sub-grade walls.

Fibers: glass OR polypropylene; reduce shrinkage cracking.

Thinset mortar (tile setting)

Modified thinset: cement + sand + latex/polymer; standard residential.

Unmodified thinset: pure cement + sand; specific membranes + natural stone.

Common brands: Custom Building Products VersaBond, Mapei, Laticrete, Bostik.

Mix to consistency: peanut butter OR drywall mud.

Coverage: 80 - 100 sq ft per 50 lb bag.

Open time: 20 - 30 min before tile must be set.

Notched trowel: matches tile size.

Tile grout types (covered in tile + grout selection)

Quick refresher: sanded (1/8"+ joints); unsanded (< 1/8" + delicate tile); epoxy (premium + shower).

Concrete repair products

Concrete patcher (Quikrete + Sakrete): fills holes + cracks.

Concrete bonding agent (Weld-Crete): improves new-to-old bond.

Epoxy concrete crack filler: structural; injection-applied.

Polyurethane crack sealant: surface; flexible.

Concrete resurfacer (Quikrete Concrete Resurfacer): thin top layer.

Cement board (Durock, Hardibacker): substrate for tile in wet areas.

Specialty mortars

Refractory mortar: high-temp; fireplaces + chimneys + boilers.

Hydraulic cement (rapid-set): stops active water leaks; sets underwater.

Mortar mix for chimneys: heat-resistant.

Stone setting mortar: thicker; for veneer.

Polymer-modified mortar: bonding to existing concrete.

Slabs + steps

Concrete slab (4"): garage floor, sidewalk, driveway base.

Concrete pad (6"): heavier loads; AC condenser, generator, equipment.

Footing: load distribution; below frost line in cold climates.

Step risers + treads: precast OR cast-in-place.

Mixing + application

By hand: bucket + trowel; small jobs.

Mixer (drum): medium jobs.

Mixer (paddle, mortar mixer): medium to large.

Truck delivery (ready-mix): 1+ yards.

Workability: should mound up but flow off trowel.

Don't over-water: weakens mortar + concrete.

Mix only what you can use: cure starts in 1 - 4 hr depending on temp.

Curing

Mortar: 24 - 48 hr to set; 28 days full strength.

Concrete: 24 hr to walk; 7 days light use; 28 days full strength.

Cure moist in hot dry weather: wet burlap OR moisture-curing membrane.

Don't freeze: protect from freezing; covers + heaters in cold.

Skim-coat / thin sections: cure slower; need protection.

Common mortar + concrete mistakes

Wrong mortar type for application. Adding water during use (re-tempering OK once; not unlimited). Insufficient cure protection (freezing, drying). Too much water in mix (weakens). Mixing too much for use time. Wrong tile thinset (modified vs unmodified per stone OR membrane). Skipping bond agent on existing concrete. Pouring on dirty / oily substrate.

Mortar bond + adhesion

Surface prep: clean + slightly damp.

Bond breakers (oil, grease, paint): scrub + remove.

Bond agent: brush on before mortar; improves adhesion.

Joint width (masonry): typically 3/8" - 1/2".

Tuckpointing: removing old mortar + applying new in same joint.

Curing in extreme weather

Cold (< 40°F): cover + heat; accelerator additive; insulating blanket; freezing damages mortar.

Hot (> 90°F): cover + mist; retarder additive; pour early morning OR late afternoon.

Rain: cover; don't pour OR set in active rain.

Wind: dries fast; cover + mist; sometimes pour overnight.

Truck stock

Mortar mix bags (Type N + Type S for repairs), thinset bag (modified), tile grout (sanded + unsanded), portland cement (small bag), masonry sand (small quantity), bonding agent, hydraulic cement (leak repair), mortar joint tools (jointer, brush), trowels (multiple), mixing pail + paddle.

Code requirements

IRC R608: masonry standards.

ACI 318: structural concrete.

ASTM C270: mortar specifications.

Local code: foundation + structural requirements per AHJ.

References

• ASTM C270 (mortar standards)
• ASTM C150 (portland cement)
• ACI 318 (concrete structural)
• ANSI A118 (tile setting standards)
• IRC R608 (masonry construction)
• Manuall internal: Common Building Materials, Tile + Grout Selection