Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Masonry Mortar and Grout
…45 unchanged lines
| ASTM C476-23 | Standard Specification for Grout for Masonry |
| TMS 402/602-22 | Building Code Requirements and Specification for Masonry Structures |
−| IBC 2021 Chapter 21 | International Building Code -- Masonry |
+| IBC 2021 Chapter 21 | International Building Code — Masonry |
| ASTM C91 | Standard Specification for Masonry Cement |
| ASTM C1329 | Standard Specification for Mortar Cement |
…79 unchanged lines
## A mortar specification method shall be selected and stated for each mortar type used on the project.
−### ASTM C270 permits two mutually exclusive methods. The proportion specification prescribes the volumetric ratio of cement, lime, and sand and requires no preconstruction strength testing; it is the default and is appropriate for the great majority of projects. The property specification instead requires laboratory testing to demonstrate a minimum 28-day compressive strength and water retention, and is used where a documented strength is required or where unusual materials are proposed. The two methods shall never be specified simultaneously for the same mortar, because a mix proportioned to the property method will rarely satisfy the proportion table and vice versa. {note}
−
−### Where the proportion specification is used, no minimum field compressive strength shall be enforced as an acceptance criterion.
−
−### The proportion method controls quality through ingredient ratios rather than strength; applying a strength acceptance threshold to a proportion-specified mortar is inappropriate because the two methods are calibrated differently. {note}
−
```datasheet
label: Mortar Specification Method
…5 unchanged lines
```
+### ASTM C270 permits two mutually exclusive methods. The proportion specification prescribes the volumetric ratio of cement, lime, and sand and requires no preconstruction strength testing; it is the default and is appropriate for the great majority of projects. The property specification instead requires laboratory testing to demonstrate a minimum 28-day compressive strength and water retention, and is used where a documented strength is required or where unusual materials are proposed. The two methods shall never be specified simultaneously for the same mortar, because a mix proportioned to the property method will rarely satisfy the proportion table and vice versa. {note}
+
+### Where the proportion specification is used, no minimum field compressive strength shall be enforced as an acceptance criterion.
+
+### The proportion method controls quality through ingredient ratios rather than strength; applying a strength acceptance threshold to a proportion-specified mortar is inappropriate because the two methods are calibrated differently. {note}
+
## A preconstruction mockup panel shall be constructed and approved before production masonry begins.
+```datasheet
+label: Mockup Panel Required
+type: radio
+options:
+ - "Yes — approved before production masonry"
+ - "No — repair/repointing of limited extent only"
+default: "Yes — approved before production masonry"
+```
+
### Mortar color and joint texture vary with mix proportions, sand source, tooling, and curing, and these variations are not visible until a substantial area has been laid. A mockup establishes the accepted appearance and the workmanship standard before large areas are built, avoiding tear-out and acceptance disputes. {note}
…10 unchanged lines
### The absorbent unit faces draw water from the grout and reproduce the in-place water-cement ratio that a nonabsorbent cylinder mold would not; this is why ASTM C1019 specifies the masonry-unit mold rather than a standard concrete cylinder. {note}
−```datasheet
−label: Mockup Panel Required
−type: radio
−options:
− - "Yes -- approved before production masonry"
− - "No -- repair/repointing of limited extent only"
−default: "Yes -- approved before production masonry"
−```
−
# Environmental and Service Conditions {toc}
…16 unchanged lines
type: select
options:
− - "Below 40 °F (4 °C) -- protect materials and work"
− - "Below 32 °F (0 °C) -- heat water and sand"
− - "Below 20 °F (-7 °C) -- heated enclosure"
−default: "Below 40 °F (4 °C) -- protect materials and work"
+ - "Below 40 °F (4 °C) — protect materials and work"
+ - "Below 32 °F (0 °C) — heat water and sand"
+ - "Below 20 °F (-7 °C) — heated enclosure"
+default: "Below 40 °F (4 °C) — protect materials and work"
unit: °F
```
…13 unchanged lines
## The mortar type shall be selected for each masonry application from ASTM C270 Types M, S, N, and O.
+```datasheet
+label: Mortar Type
+type: select
+options:
+ - "Type M (≥ 2500 psi) — below-grade, heavy-duty, high seismic/wind"
+ - "Type S (≥ 1800 psi) — general structural, reinforced, below-grade"
+ - "Type N (≥ 750 psi) — above-grade load-bearing and veneer"
+ - "Type O (≥ 350 psi) — non-load-bearing interior, restoration"
+default: "Type N (≥ 750 psi) — above-grade load-bearing and veneer"
+```
+
### Mortar type is not a quality ranking; it is a match to structural demand and exposure. Stronger mortar is also more rigid, and a mortar harder than the units it joins forces thermal and moisture movement to be relieved by cracking the (costly, irreplaceable) units rather than the (sacrificial, repointable) joints. The correct type is the lowest-strength mortar that satisfies the structural and exposure demand, not the strongest available. {note}
…5 unchanged lines
- **Type O (≥ 350 psi):** non-load-bearing interior masonry and historic or restoration work where a soft mortar is required for compatibility.
−```datasheet
−label: Mortar Type
−type: select
−options:
− - "Type M (≥ 2500 psi) -- below-grade, heavy-duty, high seismic/wind"
− - "Type S (≥ 1800 psi) -- general structural, reinforced, below-grade"
− - "Type N (≥ 750 psi) -- above-grade load-bearing and veneer"
− - "Type O (≥ 350 psi) -- non-load-bearing interior, restoration"
−default: "Type N (≥ 750 psi) -- above-grade load-bearing and veneer"
−```
−
## The mortar binder system shall be selected as portland cement-lime, masonry cement, or mortar cement.
−### Portland cement-hydrated lime is the most compatible binder system: it develops the highest bond strength, tolerates a range of exposures, and contains no intentional air entrainment, making it suitable for reinforced and grouted masonry. {note}
−
−### Masonry cement (ASTM C91) shall not be used in reinforced or grouted masonry unless the Engineer of Record approves a specific product qualified by the property specification.
−
−### Masonry cement is valued for workability, but the entrained air it carries reduces bond strength; this makes it unsuitable for reinforced and grouted applications without explicit engineering review. {note}
−
−### Mortar cement (ASTM C1329) is a pre-blended binder similar to masonry cement but with limited air entrainment and a verified minimum bond strength, making it acceptable for reinforced masonry where a pre-blended binder is preferred over field-batched portland cement-lime. {note}
−
```datasheet
label: Mortar Binder System
…6 unchanged lines
```
+### Portland cement-hydrated lime is the most compatible binder system: it develops the highest bond strength, tolerates a range of exposures, and contains no intentional air entrainment, making it suitable for reinforced and grouted masonry. {note}
+
+### Masonry cement (ASTM C91) shall not be used in reinforced or grouted masonry unless the Engineer of Record approves a specific product qualified by the property specification.
+
+### Masonry cement is valued for workability, but the entrained air it carries reduces bond strength; this makes it unsuitable for reinforced and grouted applications without explicit engineering review. {note}
+
+### Mortar cement (ASTM C1329) is a pre-blended binder similar to masonry cement but with limited air entrainment and a verified minimum bond strength, making it acceptable for reinforced masonry where a pre-blended binder is preferred over field-batched portland cement-lime. {note}
+
## Portland cement shall conform to ASTM C150 Type I or Type II.
…12 unchanged lines
### The proportion-specification mixes below give the volumetric ratios of binder to lime to damp-loose sand for the common portland cement-lime and masonry cement mortars. Sand is measured in a damp, loose condition, which is the field-realistic state and the basis for the ASTM C270 proportion table. {note}
+### The portland cement-lime proportion shall be specified as the volumetric ratio corresponding to the ASTM C270 mortar type selected.
+
```datasheet
label: 'Portland Cement-Lime Proportion (cement : lime : sand)'
type: select
options:
− - "Type M -- 1 : 0.25 : 3"
− - "Type S -- 1 : 0.5 : 4.5"
− - "Type N -- 1 : 1 : 6"
−default: "Type S -- 1 : 0.5 : 4.5"
+ - "Type M — 1 : 0.25 : 3"
+ - "Type S — 1 : 0.5 : 4.5"
+ - "Type N — 1 : 1 : 6"
+default: "Type S — 1 : 0.5 : 4.5"
```
+### The masonry cement proportion shall be specified as the volumetric ratio corresponding to the ASTM C270 mortar type selected.
+
```datasheet
label: 'Masonry Cement Proportion (masonry cement : sand)'
type: select
options:
− - "Type N -- 1 : 3"
− - "Type S -- 1 : 2.5"
−default: "Type N -- 1 : 3"
+ - "Type N — 1 : 3"
+ - "Type S — 1 : 2.5"
+default: "Type N — 1 : 3"
```
…14 unchanged lines
type: select
options:
− - "Type M -- 2500 psi"
− - "Type S -- 1800 psi"
− - "Type N -- 750 psi"
− - "Type O -- 350 psi"
−default: "Type S -- 1800 psi"
+ - "Type M — 2500 psi"
+ - "Type S — 1800 psi"
+ - "Type N — 750 psi"
+ - "Type O — 350 psi"
+default: "Type S — 1800 psi"
unit: psi
```
## Where the property specification method is selected, mortar shall have a minimum water retention of 75 % measured by flow after suction per ASTM C91.
−### Water retention is the mortar's ability to resist losing its mixing water to absorbent units; adequate retention keeps the mortar workable long enough to lay and tool the unit and lets cement hydration proceed rather than being starved of water at the bond line. {note}
−
```datasheet
label: Minimum Mortar Water Retention (property method)
…5 unchanged lines
```
+### Water retention is the mortar's ability to resist losing its mixing water to absorbent units; adequate retention keeps the mortar workable long enough to lay and tool the unit and lets cement hydration proceed rather than being starved of water at the bond line. {note}
+
## Mortar shall be machine-mixed and used within the working time appropriate to its temperature.
−### Retempering -- restoring workability by adding water to mortar that has stiffened from evaporation -- shall be permitted only once and only within two hours of initial mixing; mortar that has stiffened from initial set or that exceeds the two-hour limit shall be discarded and shall not be retempered.
+### Retempering — restoring workability by adding water to mortar that has stiffened from evaporation — shall be permitted only once and only within two hours of initial mixing; mortar that has stiffened from initial set or that exceeds the two-hour limit shall be discarded and shall not be retempered.
### Retempering replaces water lost to evaporation and is acceptable, but it must not be confused with adding water to mortar that has begun to set. Water added after the onset of set does not re-disperse the hydrating paste; it only raises the water-cement ratio and reduces strength. The single-retemper, two-hour rule draws the line between the two. {note}
…3 unchanged lines
## Grout shall conform to ASTM C476 and shall be selected as fine grout, coarse grout, or self-consolidating grout.
−### Fine grout uses sand as its only aggregate and is selected for grout spaces less than 2 inches in least dimension or where close bar spacing would obstruct coarse aggregate. {note}
−
−### Coarse grout adds pea gravel to the sand and is selected for grout spaces 2 inches or greater in least dimension, where it is more economical than fine grout for filling larger voids. {note}
−
−### Self-consolidating grout is a high-flow product that fills and consolidates under its own weight without mechanical vibration; it is specified by compressive strength and slump-flow rather than by proportions, and requires clean, unobstructed cores because mortar fins or debris that conventional grout would be vibrated past can block its flow and leave undetected voids. {note}
−
```datasheet
label: Grout Type
type: radio
options:
− - "Fine grout (sand only) -- spaces < 2 in. or close bar spacing"
− - "Coarse grout (sand + pea gravel) -- spaces ≥ 2 in."
− - "Self-consolidating grout -- no vibration, clean cores required"
−default: "Fine grout (sand only) -- spaces < 2 in. or close bar spacing"
+ - "Fine grout (sand only) — spaces < 2 in. or close bar spacing"
+ - "Coarse grout (sand + pea gravel) — spaces ≥ 2 in."
+ - "Self-consolidating grout — no vibration, clean cores required"
+default: "Fine grout (sand only) — spaces < 2 in. or close bar spacing"
```
+### Fine grout uses sand as its only aggregate and is selected for grout spaces less than 2 inches in least dimension or where close bar spacing would obstruct coarse aggregate. {note}
+
+### Coarse grout adds pea gravel to the sand and is selected for grout spaces 2 inches or greater in least dimension, where it is more economical than fine grout for filling larger voids. {note}
+
+### Self-consolidating grout is a high-flow product that fills and consolidates under its own weight without mechanical vibration; it is specified by compressive strength and slump-flow rather than by proportions, and requires clean, unobstructed cores because mortar fins or debris that conventional grout would be vibrated past can block its flow and leave undetected voids. {note}
+
## Aggregate for grout shall conform to ASTM C404.
…8 unchanged lines
## Grout shall develop a minimum 28-day compressive strength of 2000 psi when sampled and tested per ASTM C1019, or a higher strength where required by the structural drawings.
−### The required grout strength shall be taken from the structural drawings and shall not be assumed to be the code minimum.
−
−### The 2000 psi floor is the TMS 602 and ASTM C476 minimum, but the structural engineer frequently specifies 3000 psi or higher to raise the specified masonry compressive strength f'm of the grouted assembly; grout strength is one of the inputs to f'm. {note}
−
```datasheet
label: Grout Minimum 28-Day Compressive Strength
…6 unchanged lines
```
−## Grout slump at the time of placement shall be between 8 and 11 inches unless adjusted by the Engineer of Record for weather or low-absorption units.
+### The required grout strength shall be taken from the structural drawings and shall not be assumed to be the code minimum.
−### The high slump distinguishes masonry grout from concrete: the grout must be fluid enough to flow into and around reinforcement in narrow cores, and the absorbent masonry then draws off excess water to leave the in-place mix at a sound water-cement ratio. Reducing slump to concrete consistency would leave voids around the bars. {note}
+### The 2000 psi floor is the TMS 602 and ASTM C476 minimum, but the structural engineer frequently specifies 3000 psi or higher to raise the specified masonry compressive strength f'm of the grouted assembly; grout strength is one of the inputs to f'm. {note}
+## Grout slump at the time of placement shall be between 8 and 11 inches unless adjusted by the Engineer of Record for weather or low-absorption units.
+
```datasheet
label: Grout Slump at Placement
…5 unchanged lines
```
+### The high slump distinguishes masonry grout from concrete: the grout must be fluid enough to flow into and around reinforcement in narrow cores, and the absorbent masonry then draws off excess water to leave the in-place mix at a sound water-cement ratio. Reducing slump to concrete consistency would leave voids around the bars. {note}
+
# Mortar Joints {toc}
…6 unchanged lines
## Mortar joints shall be tooled to the profile specified, and the tooling profile shall not be left to field interpretation.
−### The tooling profile is a weather-resistance decision, not only an aesthetic one. Concave and V-joints compress the mortar against the unit and shed water, so they are preferred for exterior exposure; flush, raked, and struck joints leave ledges or loosely compacted faces that hold water and reduce weather resistance, and raked joints in particular are inappropriate for severe exterior exposure. {note}
−
```datasheet
label: Mortar Joint Tooling Profile
type: select
options:
− - "Concave -- exterior, best weather resistance"
− - "V-joint -- exterior, sheds water"
− - "Flush -- interior or to be coated"
− - "Raked -- interior/architectural only, not severe exposure"
+ - "Concave — exterior, best weather resistance"
+ - "V-joint — exterior, sheds water"
+ - "Flush — interior or to be coated"
+ - "Raked — interior/architectural only, not severe exposure"
- Struck
- Weathered
−default: "Concave -- exterior, best weather resistance"
+default: "Concave — exterior, best weather resistance"
```
+### The tooling profile is a weather-resistance decision, not only an aesthetic one. Concave and V-joints compress the mortar against the unit and shed water, so they are preferred for exterior exposure; flush, raked, and struck joints leave ledges or loosely compacted faces that hold water and reduce weather resistance, and raked joints in particular are inappropriate for severe exterior exposure. {note}
+
# Grout Placement {toc}
## Grout shall be placed in lifts and pours within the height limits of TMS 602 Article 7.5 for the consolidation method used.
−### A pour is the full height of grout placed before construction resumes above it; a lift is the increment placed and consolidated as one operation within that pour. The limits below keep grout from segregating under its own head and ensure each increment can be consolidated before the next is placed. {note}
−
−### Conventional grout shall be placed in lifts not exceeding 5 feet unless the grout space is provided with cleanouts and the grout demonstrably consolidates to the full pour height.
−
−### Where the consolidating vibrator cannot reach the full lift height, the lift shall be limited to 24 inches.
−
−### Conventional grout shall be consolidated by mechanical vibration within 5 minutes of placement and reconsolidated after initial water loss, except that self-consolidating grout shall be placed without vibration.
−
−### Vibration of a self-consolidating mix promotes segregation rather than consolidation, which is why mechanical vibration is prohibited for self-consolidating grout. {note}
−
```datasheet
label: Grout Pour and Consolidation Method
type: radio
options:
− - "Conventional -- 5 ft pour with cleanouts, vibrated"
− - "Conventional -- 24 in. lift, vibrated (vibrator reach limited)"
− - "Self-consolidating -- placed without vibration"
−default: "Conventional -- 5 ft pour with cleanouts, vibrated"
+ - "Conventional — 5 ft pour with cleanouts, vibrated"
+ - "Conventional — 24 in. lift, vibrated (vibrator reach limited)"
+ - "Self-consolidating — placed without vibration"
+default: "Conventional — 5 ft pour with cleanouts, vibrated"
```
+### A pour is the full height of grout placed before construction resumes above it; a lift is the increment placed and consolidated as one operation within that pour. The limits below keep grout from segregating under its own head and ensure each increment can be consolidated before the next is placed. {note}
+
+### Conventional grout shall be placed in lifts not exceeding 5 feet unless the grout space is provided with cleanouts and the grout demonstrably consolidates to the full pour height.
+
```datasheet
label: Maximum Conventional Grout Lift Height
…5 unchanged lines
```
+### Where the consolidating vibrator cannot reach the full lift height, the lift shall be limited to 24 inches.
+
+### Conventional grout shall be consolidated by mechanical vibration within 5 minutes of placement and reconsolidated after initial water loss, except that self-consolidating grout shall be placed without vibration.
+
+### Vibration of a self-consolidating mix promotes segregation rather than consolidation, which is why mechanical vibration is prohibited for self-consolidating grout. {note}
+
## Cleanout openings shall be provided at the bottom course of every cell to be grouted where the grout pour height exceeds 5 feet.
−### Mortar fins and droppings accumulate at the base of grout spaces during laying. Without cleanout openings to inspect and clear the cell bottom before grouting, these obstructions trap voids at the most structurally critical location -- the base of the wall where flexural and shear demand on the reinforcement is greatest. {note}
+### Mortar fins and droppings accumulate at the base of grout spaces during laying. Without cleanout openings to inspect and clear the cell bottom before grouting, these obstructions trap voids at the most structurally critical location — the base of the wall where flexural and shear demand on the reinforcement is greatest. {note}
### Cleanout openings shall be sealed after inspection and before grouting.
…5 unchanged lines
type: radio
options:
− - "Yes -- pours exceed 5 ft"
− - "No -- all pours ≤ 5 ft"
−default: "No -- all pours ≤ 5 ft"
+ - "Yes — pours exceed 5 ft"
+ - "No — all pours ≤ 5 ft"
+default: "No — all pours ≤ 5 ft"
```
…8 unchanged lines
## Adhered masonry veneer shall be set in mortar conforming to ASTM C270 or, where specified, in latex-modified portland cement mortar conforming to ANSI A118.4 as permitted by TMS 602.
−### Adhered veneer is bonded directly to a backing rather than supported on a shelf, so its setting mortar carries the unit in shear at the bond line. ANSI A118.4 latex-modified mortar is an alternative to ASTM C270 specifically for this condition, providing higher and more reliable bond than a conventional mortar where the veneer is thin and the backing is dense. {note}
−
```datasheet
label: Adhered Veneer Setting Mortar
…5 unchanged lines
```
+### Adhered veneer is bonded directly to a backing rather than supported on a shelf, so its setting mortar carries the unit in shear at the bond line. ANSI A118.4 latex-modified mortar is an alternative to ASTM C270 specifically for this condition, providing higher and more reliable bond than a conventional mortar where the veneer is thin and the backing is dense. {note}
+
# Repointing and Repair Mortar {toc}
## Mortar for repointing or repair of existing masonry shall match or be softer than the existing mortar, and shall not be harder than the existing units.
−### Repointing existing masonry with a mortar harder than the original -- for example replacing a soft historic lime or Type O mortar with a modern Type S or M portland cement mortar -- is one of the most damaging errors in masonry repair. The hard new joint will not yield to thermal and moisture movement, so the movement is relieved by spalling the faces of the adjacent units, which are far costlier to replace than the joints. {note}
+### Repointing existing masonry with a mortar harder than the original — for example replacing a soft historic lime or Type O mortar with a modern Type S or M portland cement mortar — is one of the most damaging errors in masonry repair. The hard new joint will not yield to thermal and moisture movement, so the movement is relieved by spalling the faces of the adjacent units, which are far costlier to replace than the joints. {note}
### For historic and soft-unit masonry, repointing mortar shall be Type N or Type O unless laboratory analysis of the existing mortar establishes that a stronger mortar is compatible.
…3 unchanged lines
type: select
options:
− - "Type O -- soft historic / restoration"
− - "Type N -- general repointing of modern masonry"
− - "Type S -- only where existing units verified compatible"
−default: "Type N -- general repointing of modern masonry"
+ - "Type O — soft historic / restoration"
+ - "Type N — general repointing of modern masonry"
+ - "Type S — only where existing units verified compatible"
+default: "Type N — general repointing of modern masonry"
```
…16 unchanged lines
## A qualified testing agency shall sample and test mortar and grout at the frequency established by the project quality-assurance program and TMS 602.
−## Mortar shall be evaluated in the field per ASTM C780, and grout shall be sampled and tested per ASTM C1019.
−
−## Grout test specimens shall be cured under conditions representative of the in-place work and tested at 28 days, with additional early-age specimens where placement schedule requires strength verification before 28 days.
−
−### Field test results that fall below the specified strength shall trigger investigation and, where directed by the Engineer of Record, evaluation of the in-place masonry; they shall not be averaged away or dismissed without investigation.
−
−### A low grout result at the base of a reinforced wall can indicate a void or a placement defect rather than a sampling anomaly, and statistical averaging conceals individual failures in the most structurally critical locations. {note}
−
```datasheet
label: Grout Test Frequency Basis
…6 unchanged lines
```
+## Mortar shall be evaluated in the field per ASTM C780, and grout shall be sampled and tested per ASTM C1019.
+
+## Grout test specimens shall be cured under conditions representative of the in-place work and tested at 28 days, with additional early-age specimens where placement schedule requires strength verification before 28 days.
+
+### Field test results that fall below the specified strength shall trigger investigation and, where directed by the Engineer of Record, evaluation of the in-place masonry; they shall not be averaged away or dismissed without investigation.
+
+### A low grout result at the base of a reinforced wall can indicate a void or a placement defect rather than a sampling anomaly, and statistical averaging conceals individual failures in the most structurally critical locations. {note}
+
# Warranty {toc}
## The Contractor shall warrant the masonry mortar and grout work against defective materials and workmanship for the period required by the Contract, and shall make good cracking, spalling, or loss of bond attributable to defective mortar or grout within the warranty period.
−### Mortar and grout defects often appear only after a full seasonal cycle of thermal and moisture movement, so the warranty exists to cover failures that are not visible at substantial completion. Cracking caused by structural movement or by foundation settlement is a separate matter from mortar and grout workmanship and is governed by the structural provisions, not this warranty. {note}
−
```datasheet
label: Workmanship Warranty Period
…5 unchanged lines
default: 1 year
```
+
+### Mortar and grout defects often appear only after a full seasonal cycle of thermal and moisture movement, so the warranty exists to cover failures that are not visible at substantial completion. Cracking caused by structural movement or by foundation settlement is a separate matter from mortar and grout workmanship and is governed by the structural provisions, not this warranty. {note}