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  4. The electrical conduit may be exposed (provided they are rated for such applications), which is common in retrofit applications or where aesthetics are not critical. Alternatively utilities can be run through the cells of the units allowing for the outlet boxes to be mounted on the surface of the assembly or flush mounted.
  5. 6 inch loadbearing CMU in low-rise construction is very feasible (and a system I personally feel is underutilized for many common applications). Structurally their design is the same as any other block size. The only unique consideration with 6 inch CMU (as with 10, 12, or other block sizes other than 8 inch) is maintaining bond when turning corners, etc.
  6. How are electrical outlets handled with single wythe CMU wall types with no further interior finishes (ie dry wall), are the conduits exposed?
  7. Is a 6" block back up wall suitable for 2 stories of a CMU cavity wall with around 4" of rigid insulation? Are there any special considerations?
  8. Personally, I do see numerous applications for the window/door surrounds that you describe...although typically they are installed as an anchored veneer along with the rest of the masonry veneer cladding. That said, there is nothing that would technically prevent an adhered veneer surround from being used - provided that it met current building code criteria...including the 15 pounds per square foot weight limit you reference. The challenge I foresee is whether such a product would be classified as a cast stone product (and accordingly meeting the requirements of ASTM C1364) or a manufactured stone veneer product (meeting the requirements of ASTM C1670). If intended to comply with ASTM C1364, establishing a mix design that met the compressive strength and absorption requirements of ASTM C1364 - while concurrently having a weight of 15 psf or less may be a challenge...but certainly possible.
  9. Very conditionally. In applications where the water will flow onto or impact the manufactured stone; I'd definitely recommend against such applications as the water will eventually erode the surface pigments...and eventually the stone. If, however, the manufactured stone is simply providing a backdrop to a waterfall without becoming wet due to the falling or splashing water, such applications may be acceptable. I would note that exterior waterfall applications such as this would require additional considerations to ensure the flowing water isn't diverted onto the surface of the stone by wind or other means.
  10. Can I install manufactured stone veneer in a waterfall application?
  11. For most practical uses in today’s construction there is no much difference. Both are blocks made out of cast concrete. Cinder blocks contain fly ash as an aggregate. That being said, most concrete contains fly ash in today’s construction of concrete masonry units.If anyone wants these type of blocks for construction contact Earth Pavers. It is one of India’s leading manufacturers of cement blocks, pavement and other building materials.
  12. As with any construction material/system, there are laboratory procedures and test methods that can simulate the effects of weathering and durability - but none can predict actual service life given the highly complex and varying exposure conditions systems and materials are exposed to. Instead, these tests are intended to provide a measure of relative performance under a given set of prescribed conditions. The only true measure of durability is in-service performance. Given that there are 1000's of concrete masonry structures that have been successfully performing for over 100 years in a wide array of environmental conditions, there is little better litmus. The key to longevity is: 1) using high quality materials, 2) good design practices; 3) proper construction techniques; and 4) appropriate maintenance over the lift of the structure.
  13. How can we measure the durability of Concrete Masonry, and what are the factors that contribute to the longevity of Concrete Masonry systems?
  14. Thanks, Craig Schriner for the information.
  15. Yes. From a building code/design perspective, shelf angles are designed and detailed the same whether they are supporting anchored clay brick, CMU, or stone veneers. The one slight difference for clay masonry that might be a consideration for very tall walls is the shelf angles may need to be spaced more closely together to accommodate the vertical expansion of the clay brick over time.
  16. Do the recommendations for clay brick veneer shelf angles apply to concrete masonry anchored veneers?
  17. 15 lb. felt signifies felt that weights 15 pounds per 100 square feet when placed on top of the sheathing of a structure. However, over time the felt has become lighter in order for manufacturers to be more cost efficient and in turn the felt is now referred to as #15 felt. #15 felt can vary in weight from 7 to 14 pounds per 100 square feet as compared to 15 lb. felt. All parties involved in the installation of sheathing wrap products must refer to their local building codes to verify which product should be purchased and installed on the structure. For a more detailed discussion on sheathing wrap products, refer to the article attached. 15 lb felt vs #15 felt (1).pdf
  18. Is there a difference between #15 felt and 15 lb. felt? How do I know I'm getting the right product?
  19. Interesting to know that there are no expectations on the absorption in the cultured stone. I suppose sealing must be included in the installation?
  20. Unfortunately, there is no 'magic' mix design to produce a given set of properties for manufactured stone. Nearly all manufactured stone is produced using lightweight aggregate to lower the weight of the installed product, however, there are slight variations in lightweight aggregate depending upon whether one is using a manufactured lightweight aggregate (expanded clay or shale for example) or a natural lightweight aggregate (such as pumice or scoria). These aggregates themselves may have varying densities and absorption characteristics that impact the properties of the finished product. Dialing in on a specific set of targeted properties includes some trial and error. Admixtures such as plasticisers will aid in not only the molding of the stone units, but removing removing voids within the stone that can lead to increased absorption. Some producers have found that in order to achieve their targeted absorption levels they need to increase the compressive strength of the mix above the minimum compressive strength requirements of ASTM C1670. That all said, ASTM C1670 does not stipulate a maximum absorption for manufactured stone units, only that it be tested for during routine quality control assessment.
  21. It's always a Best Practice to use 2 layers of WRB, Grade D asphalt saturated kraft paper being the one directly behind the metal scratch coat base.
  22. What is the water absorption rate that is acceptable in the spec? How do you achieve it with such porous materials like those used in the thin set veneer? It has been my experience that it is difficult to have low water absorption and relative low PSI material as you call out in the ASTM spec mentioned here. It may be considered a secrete formulation but i am curious what additives you are using to get both light weight and lower your water absorption.
  23. I am a manufacturer of cast stone, I am interested in feed back on the prospects of designing a thin light weight cast stone trim for accents around doors and windows that would fit the pounds per square ft requirement to apply same the veneer stone is done? Too in the event the mix design cannot be made light enough because it becomes too thick for the sq ft area of contact, would there be a market for it if it were installed mechanically through the scratch coat? Bottom line is there a demand for the trim on the thin veneer?
  24. The empirical layout and detailing recommendations of NCMA TEK 10-2C are applicable regardless of whether the CMU assembly is hollow, partially grouted, or fully grouted. If the assembly is solidly grouted because the reinforcement is closely spaced together (e.g., 8 or 16 inches on center vertical/horizontal) then it may also be worth considering the alternative crack control recommendations of TEK 10-3, which provide for an option to remove control joints altogether due to the presence of a large amount of reinforcing steel. Removing the control joints, however, does depend on the wall thickness, percentage of grouting, and reinforcement size and spacing.
  25. Are the control joint recommendations the same for a single wythe, fully grouted barrier wall, as they are for other CMU wall systems? Would the control joints themselves be different?
  26. How tall a concrete masonry wall can be designed and constructed is really a matter of vision rather than any prescriptive code requirement. I regularly see CMU walls in the 40 to 60 foot range, with some examples going even higher. Structural considerations can vary considerably from one project to another, but a general rule of thumb I use, for example, is an 8 inch block wall tends to hit its structural 'limit' around 20 to 30 feet...or more of high strength materials are used.
  27. I'm often asked if it feasible to grout 4 inch (100 mm) concrete masonry units. To which I reply "No"...or possibly "Good Luck". While there is no code prohibition on grouting hollow 4 inch CMU, the size of the cells makes doing so pretty impractical - especially if reinforcement is present. The primary reason is illustrated in the accompanying photos showing a 4 inch CMU from the top of the unit (as made) and the same unit from the bottom (as made). While the width of the cells at the top of the unit could lead one to believe grouting is possible, due to the tamper of the cells opening width transitions from about 1.5 inches to around 0.75 inches. Is it impossible to fill these hollow 4 inch units with grout - no. But if a solid 4 inch unit is needed for whatever reason(s), it's easier, faster, and less expensive to simply specify a solid 4 inch unit.
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