While concrete block masonry wall systems have proven their worth over decades of use, providing durability as well as sustainability, the PyroTherm Masonry
While concrete block masonry wall systems have proven their worth over decades of use, providing durability as well as sustainability, the PyroTherm Masonry Wall System (PMWS) offers an even better building technology, Texas Industries (TXI) product developers note. Reportedly exceeding the performance of concrete typically comprising conventional block, the PyroTherm Masonry Wall System uses an optimized mix design to produce lighter, stronger, and faster-curing masonry with the same molds and equipment that other units entail.
The mix design is distinguished primarily by the use of structural-grade TXI Expanded Shale and Clay (ES&C) fine aggregate as 100 percent of its lightweight aggregate. As recycled material, TXI ES&C fine aggregate qualifies for LEED Credit 4.1 and 4.2 Recycled Content. No other type of lightweight aggregate is introduced in the mix; however, heavyweight aggregates complying with ASTM 33 are allowed.
Second, PMWS units meet strength criteria surpassing minimum ASTM requirements. Though ordinary mix designs enable block producers to comply with ASTM C 90 minimum strengths, physical characteristics of ES&C as well as the benefits of internal curing readily contribute to higher-strength product. Minimum strength criteria for PMWS lightweight concrete masonry units dictate that the tested average net area compressive strength of three units shall equal or exceed the specified strength of 2,500 psi; and, the tested net area compressive strength of each unit shall exceed 90 percent of the specified strength of 2,500 psi.
Third, a mix containing TXI ES&C fine aggregate achieves a dry concrete density of 85 pcf. By contrast, conventional concrete in compliance with lightweight block density (mass) requirements per the Standard Specification for Loadbearing Concrete Masonry Units, ASTM C 90, exhibits a dry density less than 105 pcf. [A concrete density of 105 pcf or greater would disqualify the unit as Lightweight by the standard.] Thus, TXI officials emphasize, the PyroTherm Masonry Wall System provides higher strengths for structural support with less weight.
Additional prerequisites ensure that the PyroTherm Masonry Wall System satisfies engineering demands, as follows:
- Grout can be either normal or lightweight, meeting ASTM 476 as modified and approved by the project engineer for lightweight grout.
- Mortar is specified by the project designer as for typical masonry assembly using Type M or S.
- Regarding strength, since tables provided by code for determining masonry strength by unit strength methods are conservative, value engineering is not exploited to the full extent possible. Accordingly, if masonry strengths higher than 1,833 psi f’m are required, testing masonry prisms is advisable in accordance with the Standard Test Method for Compressive Strength of Masonry Prisms, ASTM C 1314, for actual 28-day strengths using block, mortar, or grout specified for the project. Masonry strengths of 2,000 psi up to 3,000 psi can be obtained with mix adjustments and high-strength block manufacturing techniques. Sufficient time must be allocated for prism testing.
- R-values and fire ratings can be achieved with reduced wall thickness via mix design modifications. PMWS offers an optimum balance of weight, fire rating, strength, and thermal performance, TXI representatives affirm. Û www.txiesc.com