Compressive Strength of Concrete Masonry

[zjr5273]

Good Afternoon,

I am reviewing TMS 530-13 & 602-13 - Building Code Requirements and Specifications for Masonry Structures. Table 2 - Compressive strength of masonry based on the compressive strength... provides a list of net compressive strengths up to a value of 3,000 psi. Im curious if anyone has specified a compressive strength higher than what is shown on the table. In my understanding, there is no limit to the compressive strength that can be specified so long as testing is performed to validate that the masonry achieved the desired compressive strength.

Please correct me if I am wrong or if there is a section I am missing the states the maximum permitted compressive strength.

Thanks,

rzoppa

 

[masonrygeek]

Table 2 of the TMS 402/ACI 530, called the Unit Strength Method, is a conservative measure of the compressive strength of the masonry. Recent research helped develop the updated values in this table (NCMA FAQ 5-14). In the research, there were very few tests with units over 5,500 psi which resulted in assembly strengths upwards of 4800 psi. Based on the fewer tests, the table was capped at an f'm of 3,000 psi. You can exceed these values, but you need to use the prism test method, which is a more accurate measure of the assemblage. Of course, you may need to ask yourself, do you really need strengths that high since it may be the flexural behavior that limits a design?