Since 1946, Elliott Block Co. has been PROUDLY SERVING
the Inland Empire and surrounding areas including the cities of:
29 Palms, Adelanto, Aguanga, Alberhill, Aliso Viejo, Alpine, Alta Loma, Anaheim, Anaheim Hills, Anaheim Hills, Anza, Apple Valley, Beaumont, Balboa, Balboa Island, Banning, Bear Creek, Beaumont, Bermuda Dunes, Beverly Hills, Bloomington, Bonsall, Borrego Springs, Box Springs, Brea, Bryn Mawr, Buena Park, Buena Park, Carson, Cherry Valley, Cabazon, Cabazon, Cajon Junction, Calabasas, Calimesa, Camp Pendleton, Canyon Country, Canyon Crest, Canyon Lake, Canyon Springs, Capistrano Beach, Cardiff by the Sea, Carlsbad, Carmel Valley, Casa Blanca, Cathedral City, Cherry Valley, Chino, Chino Hills, Chino Hills, Chula Vista, Claremont, Coachella, Northern, Colton, Corona, Corona Del Mar, Coronado, Costa Mesa, Coto De Caza, Cottonwood, Covina, Cowan Heights, Crestline, Cypress, Dana Point, De Luz, Del Mar, Del Mar, Desert Hot Springs, Devore, Diamond Bar, Dove Canyon, East Highland, El Cajon, El Cariso Village, El Cariso Village, W, El Cerrito, El Toro, Encinitas, Escondido, Etiwanda, Fallbrook, Fontana, Foothill Ranch, Fountain Valley, Fullerton, Gardena, Garden Grove, Garner Valley, Gavilin Hills, Gilman Hot Springs, Glen Avon, Glen Ivy Hot Springs, Glen Oaks, Glen Oaks, Rancho Ca, Glen Valley, Glendale, Glendora, Good Hope, Grand Terrace, Green Acres, Hemet, Hemet by Sage, Hesperia, Hidden Hills, Highgrove, Highland, Highland Park, Hollywood, Home Garden, Homeland, Horsethief Canyon, Huntington Beach, Idyllwild, Indian Hills, Indian Wells, Indio, Irvine, Juniper Flats, Jurupa, Landers, La Cresta, La Habra, La Jolla, La Mirada, La Palma, La Quinta, La Sierra, La Verne, Ladera, Laguna Beach, Laguna Hills, Laguna Niguel, Lake Arrowhead, Lake Elsinore, Lakeland Village, Lakeside, Lakeview, Lancaster, Lemon Heights, Loma Linda, Long Beach, Lytle Creek, Mead Valley, Meadowbrook, Meadowbrook, Menifee, Mentone, Midway City, Mira Loma, Mission Viejo, Modjeska, Montclair, Moreno Valley, Morongo Valley, Mountain Center, Murrieta, Murrieta Hot Springs, Muscoy, Newhall, Newport Beach, Norco, Nuevo, Oak Glen, Oak Grove, Oceanside, Ontario, Orange, Ortega Mountains, Oxnard, Pala, Pala Mesa Village, Palm Desert, Palm Springs, Palmdale, Pasadena, Pedley, Pelican Hills, Pelican Point, Perris, Phelan, Pico Rivera, Pine Cove, Pine Meadows, Pinyon Pines, Pinyon Pines, Placentia, Pomona, Poway, Quail Valley, Rainbow, Ranchita, Rancho Bernardo, Rancho California, Rancho Capistrano, Rancho Cucamonga, Rancho Mirage, Rancho Santa Fe, Rancho Santa Margari, Redhawk, Redlands, Redlands, Rialto, Riverside, Romoland, Rowland Heights, Rubidoux, Sage/Woodch, San Bernardino, San Clemente, San Diego, San Dimas, San Francisco, San Jacinto, San Juan Capistrano, San Juan Hot Springs, San Marcos, Santa Ana, Santa Clarita, Santa Clarita, Santa Fe Springs, Seal Beach, Sedco Hills, Silver Lakes, Silverado, Solana Beach, Spring Valley, Stanton, Sun City, Sunnymead, Sunnyslope, Sunshine Summit, Temecula, Tenaja, Thousand Palms, Trabuco Canyon, Tucalote, Tustin, Upland, Val Verde, Valley Center, Valyermo, Victorville, Villa Park, Vista, Walnut, Warner Springs, West Covina, Westminster, Whittier, Wildomar, Wilmington, Winchester, Woodchuck, Woodcrest, Woodland Hills, Yorba Linda, Yucaipa, Yucca Valley
In expressing the size of a CMU*, it is necessary to state dimensions in proper order: width, height, length (w x h x l). For example, a 6 inch wide, 16 inch long, and 8 inch high unit is termed a 6 x 8 x 16. Reversing the order of the first two dimensions would describe a completely different sized block.There are three methods to describe the dimensions of a CMU*. Each of these are termed: nominal, specified, and actual.| Nominal dimensions are those used in stating the CMU unit size. They are equal to the specified dimension plus the thickness of the mortar joint. The nominal dimensions compensate for a 3/8 inch mortar joint for precision block and split face block, and a 1/2 inch mortar joint for slump block. |
| Specified dimensions are those specified for the manufacture of masonry units or the construction of masonry. Calculations are based on specified dimension. |
Example:
| Precision Block : | Slump Block : | |
| Nominal - 6 x 8 x 16Specified - 5 5/8 x 7 5/8 x 15 5/8 |
Nominal - 8 x 6 x 16Specified - 7 1/2 x 5 1/2 x 15 1/2 | |
| Note a difference of 3/8 inch. |
Note a difference of 1/2 inch. | |
| Actual dimensions are the measured dimensions of the physical CMU unit. UBC** and ASTM†standards allow the actual dimensions of a CMU to vary within a permissible range from the specified dimension. |
WEIGHT CLASSIFICATIONS OF CMU
There are three classifications of weight concerning the CMU: normalweight, mediumweight, and lightweight. All of these are expressed in pounds per cubic foot.
Normalweight is 125 lbs./cu. ft. and over. Units stocked in normalweight include slump block units and fence units (stucco block and others). Certain colors are stocked only in normalweight.
Mediumweight is less than 125 lbs./cu. ft. and ranges down to 105 lbs./cu. ft. "Structural" types and sizes are stocked most extensively in mediumweight.
Lightweight is less than 105 lbs./cu. ft. Lightweight products are normally grey and stocked in selected sizes.
*CMU is short for "Concrete Masonry Unit"
**Uniform Building Code
†American Society for Testing and Materials
ASTM & UBC STANDARDS FOR CMU
Elliott Block manufactures its products to meet or exceed applicable standards of the Uniform Building Code (UBC) and the American Society for Testing and Materials (ASTM). UBC and ASTM standards define characteristics of strength and quality. Which standard applies to a particular product may depend on its configuration and/or use. Please refer to product sections and the specification section for further information.
STRENGTH NOMENCLATURE OF CMU
Statements of CMU strength can be in a variety of expressions. Unfortunately, a less than clear understanding of what the different expressions represent can lead to confusion, or worse. The discussion following is offered to clarify those expressions, of which, there are three: two for CMU strength, and one for the masonry assemblage.
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Compressive strength of an individual CMU is expressed in terms of gross or net psi. | |
| Gross compressive strength is the psi calculated from the gross area of the unit, which is the entire cross-sectional area including cells. The minimum average gross compressive strength for UBC and ASTM is 1000 psi. |
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| Net compressive strength is the psi calculated from the net area of the unit, which is the cross-sectional area minus the average area of cells. The minimum average net compressive strength for UBC and ASTM is 1900 net psi. |
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It is important to note the test of a single unit yields a result expressible in both terms. The only difference is in the calculation based upon gross or net area.
The third expression of strength is notated as f'm which UBC defines as the "specified compressive strengths of masonry at the age of 28 days." Notice it is the strength of masonry, not units. In other words, it is the compressive strength of the assemblage of masonry units, mortar, and, if required, grout.
f'm is the value used in the design of masonry walls. When the design utilizes prescribed minimum strengths of CMU, mortar and grout per their respective standards, the given f'm is 1500 psi based on net area.
Beyond that, UBC has three provisions for selecting the f'm value:1. By prism testing2. Based upon an approved prism test record (75% of the average)3. As selected from Table No. 24-C in the 1988 UBC.
Compression testing of prisms affords the most accurate determination of f'm. A prism is a sample assemblage of masonry units, mortar joints, and if required, grout similar to the one shown. For concrete masonry, such testing has indicated "a rule of thumb" relationship between prism compressive strength and the individual strengths of CMU and grout from which it is constructed:
| The f'm is approximately 80% of the CMU and the grout strengths or-- CMU and groutstrengths are approximately 125% of the f'm value |
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| The compressive strength of grout must be equal to or greater than the compressive strength of the CMU. For example, a High-Stress unit of 3750 net psi should facilitate an f'm of 3000 net psi. |
Alternatively, in Table 24-C UBC allows an "assumed" value of f'm to be selected based upon specifying the net compressive strength of the masonry unit. For example, specifying the same High-Stress unit as above at 3750 net psi, an f'm of 2500 net psi would be allowed without substantiation by prism test. However, in Seismic Zones 3 and 4, an f'm over 1500 net psi may require verification by prism test anyway. (See UBC Section 2407 (h)4.)
Compressive Strength Comparisons
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