Durability
Properties of masonry mortar related to its durability include:
- Resistance to freeze-thaw deterioration. Research[1][2][3] shows that air-entrainment levels of at least 10 to 12 percent are needed to provide effective resistance to freeze-thaw deterioration.
- Drying shrinkage characteristics. Results of laboratory test shown in Figure I indicate that the drying shrinkage of Masonry Cement Mortars is about half that of Portland Cement-Lime Mortars (See Figure I).
- Resistance to sulfate attack. Masonry Cement Mortars also demonstrate significantly greater sulfate resistance than Portland Cement-Lime Mortars (See Figure II).
- Water permeance. The properties of Masonry Cement Mortars assure that the designer's and masons' needs are met in achieving watertight masonry construction. Laboratory research[4] has confirmed the excellent performance of Masonry Cement Mortars in water permeance tests (See Figure III).
Appearance
Since Masonry Cement color is laboratory controlled and Masonry Cement offers the simplicity of the one bag system of batching, it is easier to achieve consistent color cement for a prefect appearance in the finished job.
Installation
Preparation
CEMEX’s Type N Masonry Cement, Type S Masonry Cement and Type M Masonry Cement are proportioned with sand meeting ASTM C-144, according to Table 4, and will produce mortar meeting the requirements of ASTM C-270 under the proportion specifications. Under the property requirements of ASTM C-270, however, cement-to-sand proportions for the job mixed mortar are to be in the range of 1:2¼ to 1:3½, and the mortar must be pre-tested in the laboratory before the job begins.
Machine mixing should be used whenever possible. First, with mixer running, add most of the water and half the sand. Next, add the Masonry Cement and the rest of the sand. After one minute of continuous mixing, slowly add the rest of the water. Mixing should continue for at least three minutes; extending mixing up to five minutes improves mortar.
Application
Good workmanship principles are required for successful application, including proper filling of head and bed joints, careful placement of units, appropriate tooling of the joint, modification of construction procedures and/or schedules to adapt to extreme weather conditions[5][6] and proper cleaning procedures.
Masonry joints should be tooled at the same degree of stiffness and moisture. If joints are tooled too early, excess water will be drawn to the surface, producing lighter joints. The joints will appear dark and discolored if tooling is done after stiffening has started.
Hot Weather and Retempering
Mortars exposed to hot winds and full sun will tend to lose workability due to the evaporation of water. Common sense precautions should be taken to protect the mortar such as shading the mixer, wetting mortar boards, covering wheelbarrows and tubs, and balancing mortar production to meet demand.
If it is necessary to restore workability, mortar may be retempered by adding water and remixing. No mortar should be used or retempered beyond 2½ hours after the initial mixing.
Cold Water Precautions
Mortar should be maintained at a minimum temperature of 40° F as prescribed by standard cold weather masonry specifications. Cold weather admixtures should be approved by the architect.
Availability
CEMEX’s Portland Cements can be ordered by contacting at CEMEX Customer Care at:
Customer Care | 1-800-992-3639
Guarantees
CEMEX, Inc. guarantees Broco Stucco Cement when shipped from our mill or terminals to meet the current requirements of ASTM C-1328, “Standard Specification for Plastic (Stucco) Cement” and ASTM C-91, “Standard Specification for Masonry.”
Maintenance
Avoid use of harsh chemical cleaners or strong acid solutions in cleaning masonry.
| TABLE 3 Physical Properties of Masonry Cement Mortars (ASTM C-270) | ||
|---|---|---|
| Mortar Type | Compressive Strength 2” Cubes at 28 Days min., psi (MPa) | Water Retention Minimum % |
| N | 750 (5.2) | 75 |
| S | 1800 (12.4) | 75 |
| M | 2500 (17.2) | 75 |
| TABLE 4 Masonry Cement Mortar - Proportions by Volume (ASTM C-270) | |||||
|---|---|---|---|---|---|
| Mortar Type | Portland Cement | Masonry N | Cement S | Type M | Sand |
| N | - | 1 | - | - | 2-1/4 - 3 |
| S | 1/2 | 1 | - | - | 3-3/8 - 41/2 |
| S | - | - | 1 | - | 2-1/4 - 3 |
| M | 1 | 1 | - | - | 4-1/2 - 6 |
| M | - | - | - | 1 | 21/4 - 3 |
Technical Services Personnel
CEMEX personnel are available to provide technical assistance by contacting Customer Care at: 1-800-992-3639
Warranty
CEMEX warrants that the products identified are in accordance with the appropriate current ASTM and Federal Specifications. No one is authorized to make any modifications or addition to this warranty. CEMEX makes no warranty or representation, either expressed or implied with respect to this product and disclaims any implied warranty of merchantability or fitness for a particular purpose.
As CEMEX has no control over the other ingredients mixed with this product or the final application, CEMEX does not and cannot warrant the finished work.
In no event shall CEMEX be liable for direct, indirect, special, incidental or consequential damages arising out of the use of this product, even if advised of the possibility of such damages. In no case shall CEMEX’s liability exceed the purchase price of this product.