Masonry Magazine May 1965 Page. 13
СМА ТЕК
tional Concrete Masonry Association
An Information series from National Concrete Masonry Association
Concrete Masonry Basements
ΑΙΑ 10-C
TABLE I-MORTAR MIXES FOR BASEMENT CONSTRUCTION, ASTM C 270-64T
MATERIALS
masonry units
To assure architects and builders of the finest load-bearing quality for basement construction in concrete masonry, it is recommended that concrete masonry designated "Q BLOCK masonry" be used. Q BLOCK masonry is a registered name given to hig high quality concrete block which meets specified standards estab-lished under the new Q BLOCK quality control program of the National Con-crete Masonry Association. Grade P or Grade U load-bearing concrete masonry units manufactured to Q BLOCK speci-fications exceed American Society for Testing and Materials Standards; are tested at regular intervals to assure that these standards are maintained; are especially recommended for basement wall construction:
Hollow Load Bearing ASTM C 90-64T
Solid Load Bearing ASTM C 145-64T
Qualified manufacturers of Q BLOCK masonry units display a "Certificate of Quality" in their sales office. Be sure to specify Q BLOCK masonry whenever you design or build concrete masonry basements. It's your assurance of the highest quality in basement wall con-struction.
mortar
Bond is an important factor in building basement walls with sufficient bending stiffness to resist the pressure exerted by backfilling. Either high or moderate strength mortars are preferred because of their superior bond to concrete masonry units. Table I lists the mortar mixes for basement construction. The moderate strength mortar (Type S) has proven particularly well suited for base-ment construction.
| Mortar Type, C 270 | Portland Cement | Masonry Cement | Hydrated Lime | Sand, Damp Loose Volume |
| - | - | - | - | - |
| M (High Strength) | 1 | - | ¼ | - |
| S (Moderate Strength) | 1 | 1 (Type II) | - | - |
| | 1 | - | ¼ to ½ | Not less than 2% and not more than 3 times the sum of the volumes of the cements and lime. |
| N (Low Strength) | ½ | 1 (Type II) | - | - |
| | 1 | - | ½ to 14 | - |
| | - | 1 (Type II) | - | - |
TABLE II-MAXIMUM DEPTH BELOW GRADE (HEIGHT OF FILL) FOR VARIOUS CONCRETE MASONRY BASEMENT WALLS
| Wall Construction Nominal Thickness, in., and Type of Unit | Maximum Depth Below Grade, feet, when walls support: |
| - | - |
| | Frame Construction | Masonry, or Masonry Veneer Construction |
| Hollow Load-Bearing: | | |
| 8" | 5' | 5' |
| 10" | 6' | 7' |
| 12" | 7' | 7' |
| Solid Load-Bearing: | | |
| 8" | 5' | 7' |
| 10" | 7' | 7' |
| 12" | 7' | 7' |
| *Based on FHA "MPS" for average soil conditions. | | |
estimating materials
Make the job easy and economical by taking maximum advantage of full length and half length concrete masonry units to minimize job site cutting.
The number of concrete masonry units and amount of mortar required can easily be calculated for each 100 sq. ft. of basement wall by using Table III. Values shown in the table provide mor-tar joints to be 3%-in. in thickness, that face-shell mortar bedding will be em-ployed, as well as a 10% allowance for waste.
In order to obtain the desired running bond pattern for maximum stability and a pleasing interior finish, concrete masonry basement walls 10-in. or 12-in. require special attention (Figure 1, turn page).
TABLE III
| Actual Height of Units, Inches | No. of Units per 100 sq. ft | Cu. Ft. Mortar per 100 sq. ft. |
| - | - | - |
| 7% (Modular) | 113 | 8.5 |
| 3% (Modular) | 225 | 13.5 |
| 8 (Nonmodular) | 103 | 8.0 |