Three classes of specialty cementitious materials were evaluated for their potential benefits in sound absorption including a Foamed Cellular Concrete (FCC) with density ranging from 400 – 700 kg/m3, Enhanced Porosity Concrete (EPC) incorporating 20-25% open porosity, and a Cellulose Cement Composite (CCC) with density 1400 – 1700 kg/m3. Cylindrical specimens of these materials were tested for acoustic absorption in an impedance tube. The FCC specimens showed absorption coefficients ranging from 0.20 to 0.30, the higher value for lower density specimens. The closed disconnected pore network of FCC hinders sound propagation, thereby resulting in a reduced absorption, even though the porosity is relatively high. The most beneficial acoustic absorption was observed for EPC mixtures. When gap-graded with proper aggregate sizes, these no-fines EPC mixtures dissipate sound energy inside the material through frictional losses. The cellulose fiber cement composites use cellulose fibers at high volume fractions (~7.5%), which are believed to provide continuous channels inside the material where the sound energy can be attenuated. By engineering the pore structure (by careful aggregate grading as in EPC, or incorporating porous inclusions like morphologically altered cellulose fibers) cementitious materials that have the potential for significant acoustic absorption could be developed.

The use of lightweight concrete has many advantages over conventional concrete. The reduced self-weight of lightweight concrete will reduce gravity load and seismic inertial mass. The lightweight concrete reported here has compressive strengths from 8 to 50 MPa with dry densities from 800 to 1400 kg/m3, which is strong enough for any load-bearing and non-load-bearing applications. The compressive strength to flexural strength ratio increases as the compressive strength of the concrete increases. The introduction of a small amount of fiber does not affect the flexural strength and drying shrinkage of the concrete, but improves the ductility and handling properties of the product very significantly. The lightweight concrete has a higher moisture loss during drying, but a lower shrinkage than the normal weight concrete due to the buffer effect of the moisture in the lightweight aggregate. Properly designed fiber-reinforced ultra lightweight concrete can be easily cut, sawed and nailed like wood.

Autoclaved aerated concrete (AAC) is a lightweight uniform cellular material, first developed in Sweden in 1929. Since that time, plain and reinforced AAC building components have been widely used in Europe and other parts of the world. Until recently, however, AAC was relatively unknown to the United States precast construction market. Today, AAC prefabricated elements are gaining rapid acceptance in the United States due primarily to increasing energy cost, environmental concerns, and the ease of construction using AAC elements. Although AAC is a well-recognized building material in Europe, very little research work has been done on U.S.-produced AAC products. The primary objective of this work was to study the structural behavior of U.S.-made reinforced AAC elements. The laboratory test program included most commonly used reinforced AAC elements: floor panels, lintels, and wall panels. Two U.S. manufacturers supplied the AAC elements. Floor panels and lintels were tested in bending, whereas the wall panels were tested under axial or eccentric loading. The ultimate load capacity, cracking, deflection, and failure mode were observed and recorded for each test. The results provide a database that will be used to refine the analytical methods for the structural design of reinforced AAC elements. This information is needed to enhance AAC design methodologies and lay the foundation for establishing AAC as a reliable engineered construction material in the U.S.

This paper summarizes the initial phases of the technical justification for proposed design provisions for AAC structures in the US. It is divided into two parts. The first part gives general background information, and presents an overall design strategy. Autoclaved aerated concrete (AAC), a lightweight cementitious material originally developed in Europe more than 70 years ago and now widely used around the world, has recently been introduced into the US construction market. AAC elements can contain conventional reinforcement in grouted cores, either alone or with factory-installed reinforcement. To facilitate the use of AAC in the US market, an integrated seismic-qualification program has been carried out, involving general seismic design provisions, specific element design provisions, and material specifications. The second part describes the design and testing of a suite of 14 AAC shear wall specimens, with aspect ratios from 0.6 to 3, under in-plane reversed cyclic loads at the University of Texas at Austin. The results of these tests have been used to develop predictive models and reliable design equations for AAC shear walls, the primary lateral force-resisting element of AAC structural systems.

Autoclaved aerated concrete (AAC) is a lightweight uniform cellular material, first developed in Sweden in 1929. Since that time, AAC building components have been widely used in Europe and other parts of the world. Until recently, however, AAC was relatively unknown to the United States precast construction market. Today, AAC is gaining rapid acceptance in the United States due primarily to increasing energy cost and environmental concerns. Although AAC is a well-recognized building material in Europe, very little research work has been done on American-produced AAC components. The goal of the testing program was to further develop the database of the material properties and structural behavior of American-made AAC by testing plain AAC elements from three different manufacturers. Manufacturers and designers will be provided with information that will help to promote AAC as a reliable engineered construction material in the U.S. Tests performed on the plain AAC consisted of compressive strength, flexural tensile strength, shear strength, and modulus of elasticity.