International Concrete Abstracts Portal

Editors: Corina-Maria Aldea and Mahmut Ekenel

This CD contains 8 papers from sessions sponsored by ACI technical committees 544, 549, and 130 at the Fall 2012 ACI Convention in Toronto and two technical sessions at the Fall 2013 ACI Convention in Phoenix. The topics of the papers cover sustainability aspects of using fiber reinforced concrete ranging from durability and interface mechanisms of natural fiber reinforced concrete (FRC), evaluation of eco-mechanical performance of FRC, reducing carbon dioxide emissions of concrete, as well as applications of fiber reinforcement for self-consolidating concrete, bridge link slabs, extruded prefabricated elements, slab systems and fabric-reinforced cementitious matrix systems for strengthening unreinforced masonry walls.

Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-299

Masonry as a building technology meets many of the attributes of sustainable construction, thus an economical alternative to demolish-rebuild existing deficient masonry structures is to retrofit them with novel strengthening systems. Current retrofit techniques used to improve flexural capacity of un-reinforced masonry (URM) walls include both internal and external reinforcement with common materials, namely: steel bars, plates, and most recently fiber-reinforced polymers (FRPs). However, significant margins exist to advance these rehabilitation systems by addressing economic, technological, and environmental issues. This paper investigates the effectiveness of strengthening URM walls using carbon fabric-reinforced cementitious matrix (FRCM) as a technique to enhance pseudo-ductility and flexural capacity. The paper reports on the results obtained by testing a total of 18 masonry walls made of clay bricks and concrete blocks strengthened with two different FRCM schemes (one and four fabrics) subjected to uniformly distributed out-of-plane loading were tested. Experimental data from other research programs using FRP system are also presented to show that when normalized flexural capacity is related to a calibrated reinforcement ratio, the two technologies provide similar enhancements.

PrimeComposite, a steel fiber reinforced concrete (SFRC) containing proprietary additives to control hygral shrinkage, provides significant reductions in CO2 emissions per square meter and improved performance over traditional slab on grade systems. This paper describes the development of the PrimeComposite system including the structural design approach, which is based upon full-scale mechanical testing results presented here. A typical PrimeComposite slabs on grade is 10 cm thick with single-casting (jointless) areas of up to 6500 m2. At this thickness, rack system loads of 140 kN (back-to-back leg loads) are safely supported.

This research investigated as a sustainable production technique, the application of calender extrusion in the production of cement fiberboards. Use of the technique was successful for the production of non-structural building elements. The properties of the produced composites are discussed in this paper. Glass, polyvinyl alcohol (PVA), and polypropylene (PP) fibers were used. The research involved an experiment to examine the mechanical properties and microstructure of the composites. The experimental results showed that calender extrusion may be a promising method for sustainable production of thin and wide cement composites. Various forms of cement composites can be produced with this method as well. Results indicate that the mechanical properties of cement composites produced with this method are dependent on the processing direction. Processed composites have adequate screw head pull-through and freeze-thaw resistance. Higher MOR values were obtained for water cured specimens compared to air cured ones.

Un-reinforced masonry (URM) walls have proven to have low shear strength to withstand in-plane loads caused by earthquakes. Retrofitting masonry walls with novel materials such as fiber-reinforced composites has shown to increase the in-plane shear capacity of the walls and minimize damage by enhancing pseudo-ductility. In this study, a new fabric-reinforced cementitious matrix (FRCM) composite system is applied to URM walls to determine its feasibility as an externally-bonded retrofitting technique. The experimental program consists of testing under diagonal compression a total of 18 wall specimens, made from clay bricks and concrete blocks with two FRCM strengthening reinforcement schemes (one and four plies fabric). The experimental results demonstrate the effectiveness of FRCM strengthening on improving the shear capacity of masonry walls. Experimental data from other research programs using fiber reinforced polymer (FRP) composites are presented to demonstrate that when the normalized shear capacity is related to a calibrated reinforcement ratio, the two technologies show similar enhancements.