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  April 2015  
 
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Concrete International April 2015 No. 4 Complete Issue
Concrete International April 2015 No. 4 Complete Issue

Conserving Twentieth Century Architecture
Modern architecture is one of the defining artistic expressions of the twentieth century and is increasingly at risk. The Getty Foundation in Los Angeles, CA, awarded 10 grants in 2014 as part of a major philanthropic initiative focused on the conservation of twentieth century architecture around the world. Called "Keeping It Modern," the effort will address the considerable challenges involved with the conservation of modern architectural heritage through support for key model projects. The grant projects, each chosen for its architectural significance and potential to advance conservation practices related to modern architecture, are briefly described.

Using Self-Consolidating Concrete for Bridge Repairs
Bridge substructure repairs that were completed using self-consolidating concrete (SCC) are described. The Virginia Department of Transportation (VDOT) has successfully used SCC on bridge repair projects for about 5 years. Placement and testing requirements for SCC are similar to those for conventional concrete, the required formwork provides initial protection against moisture loss, and the finish can be as smooth as the formwork surface. Completed repairs show that SCC can be successfully placed, and the finished product has minimal cracking.

Opportunities from Alternative Cementitious Materials
The article discusses various alternative cementitious materials (ACMs) and means for industry acceptance of those materials. ACMs have the potential to provide major reductions in the collective environmental impacts related to concrete production because they can be produced with significantly lower greenhouse gas emissions and energy consumption than portland cement. They can also exhibit improved durability resulting in increased service life. ACMs described in this article include geopolymers, activated glassy cements, hydraulic fly ash cements, activated slag cements, calcium aluminate cements, calcium sulfoaluminate cements, magnesia based cements, and CO2-cured cements.

Structural Repair of Concrete Cracks
Epoxy crack injection can be used for structural repair of cracks resulting from single occurrence events such as accidental overloads, vehicular impact, earthquake, restrained shrinkage, or excessive thermal differential in mass concrete. Typical applications include foundations, columns, beams, bridge decks, and bridge superstructures. The article describes elements that contribute to the successful and efficient application of epoxy crack injection—capping paste, injection ports, the injection resin, and the delivery system.

2014 ICRI Project Awards
The International Concrete Repair Institute (ICRI) awarded the Project of the Year and two finalists and nine Awards of Excellence for the 2014 ICRI Project Awards.

Awards at The ACI Concrete Convention and Exposition—Spring 2015
At the Opening Session of The ACI Concrete Convention and Exposition in Kansas City, MO, ACI will recognize a group of members for outstanding achievement and service to the Institute.

ACI Technical Committee Chairs Appointed
Before The ACI Concrete Convention and Exposition – Spring 2015, the ACI Technical Activities Committee selected Chairs for 41 technical committees.

CEMEX Building Award for Outstanding Architecture and Construction
Recognizing buildings that stand out for their construction, conceptual, technical, and aesthetic solutions, CEMEX, S.A.B. de C.V., announced the winners of the XXIII edition of the CEMEX Building Award for 2014.

Concrete Q&A
Q. I understand that ACI 546R recommends limiting chipping hammers to 15 lb to prevent bruising and microcracking of the concrete around a repaired zone. Can you confirm that this limit refers to the weight of the hammer itself and is not a measure of the energy imparted to the concrete (that is, could the value be 15 ft-lb rather than 15 lb)? It seems that different types of hammers (for example, electric, pneumatic, and hydraulic) could impart different amounts of energy to the concrete even if they have identical weights. Is the weight of the hammer the major factor that affects microcracking?

 


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