P. Ziehl, D. Rizos, J.
Caicedo, F. Barrios, R. Howard, and A. Colmorgan
Department of Civil and Environmental Engineering , University of South Carolina, 300 Main Street, Columbia, South Carolina 29208
Proper concrete compaction is very important to the structural integrity and overall quality in hardened concrete. Therefore, normal concrete requires internal and external vibration to properly compact the concrete and ensure that it completely fills all voids in the formwork eliminating unwanted entrapped air. Self-Consolidating Concrete (SCC), also known as self-compacting concrete, is a highly flowable concrete that is capable of filling formwork without using conventional vibration techniques while maintaining its cohesiveness. SCC was first introduced in Japan in the late 1980s by researchers at the University of Tokyo. The need for this new type of concrete was brought about by problems associated with poor compaction due to a decrease in skilled laborers in Japan. Since its introduction SCC has been widely accepted in Japan and all over the world including the United States where it was introduced in the late 1990’s. Although it was first introduced in the commercial market, state agencies have recently been gaining interest in the material for use in highway bridge construction. The reduction in required laborers could potentially save DOTs money by lowering production cost for the fabricator.
Currently SCC is used in many commercial applications and is gaining acceptance from many state DOTs for use in precast prestressed bridge girders. SCC is advantageous for many reasons including: (i) the number of workers required and the noise produced by mechanical vibration is reduced significantly; (ii) the safety hazards of workers on top of the girders is eliminated; (iii) the surface finish of the concrete can be more smooth than that of conventional concrete; (iv) formwork damage from mechanical vibration is reduced, increasing the life of the forms; (v) reinforcing bar configurations are not damaged; (vi) improved bond of concrete to prestressed strands could reduce strand end-slip and the top bar effect; and (vii) SCC is able to fill complicated shapes and congested reinforcement areas better than vibrated concrete.
This research report addresses the design and resulting properties of normal weight mix designs that were developed at the University of South Carolina and the testing of full-scale lightweight concrete AASHTO Type III girders. Both aspects address material testing for properties in the fresh and hardened states. Fresh properties include slump spread, filling ability, passing ability, and air content. Hardened properties include compressive strength, modulus of elasticity, creep, shrinkage, chloride permeability, and freeze-thaw durability. Testing of the girders includes transfer length, end-slip, midspan deflections, midspan strains, and internal curing temperatures. Summaries and conclusions are provided along with recommended guidelines for implementation.
Department of Civil and Environmental Engineering , University of South Carolina, 300 Main Street, Columbia, South Carolina 29208
Proper concrete compaction is very important to the structural integrity and overall quality in hardened concrete. Therefore, normal concrete requires internal and external vibration to properly compact the concrete and ensure that it completely fills all voids in the formwork eliminating unwanted entrapped air. Self-Consolidating Concrete (SCC), also known as self-compacting concrete, is a highly flowable concrete that is capable of filling formwork without using conventional vibration techniques while maintaining its cohesiveness. SCC was first introduced in Japan in the late 1980s by researchers at the University of Tokyo. The need for this new type of concrete was brought about by problems associated with poor compaction due to a decrease in skilled laborers in Japan. Since its introduction SCC has been widely accepted in Japan and all over the world including the United States where it was introduced in the late 1990’s. Although it was first introduced in the commercial market, state agencies have recently been gaining interest in the material for use in highway bridge construction. The reduction in required laborers could potentially save DOTs money by lowering production cost for the fabricator.
Currently SCC is used in many commercial applications and is gaining acceptance from many state DOTs for use in precast prestressed bridge girders. SCC is advantageous for many reasons including: (i) the number of workers required and the noise produced by mechanical vibration is reduced significantly; (ii) the safety hazards of workers on top of the girders is eliminated; (iii) the surface finish of the concrete can be more smooth than that of conventional concrete; (iv) formwork damage from mechanical vibration is reduced, increasing the life of the forms; (v) reinforcing bar configurations are not damaged; (vi) improved bond of concrete to prestressed strands could reduce strand end-slip and the top bar effect; and (vii) SCC is able to fill complicated shapes and congested reinforcement areas better than vibrated concrete.
This research report addresses the design and resulting properties of normal weight mix designs that were developed at the University of South Carolina and the testing of full-scale lightweight concrete AASHTO Type III girders. Both aspects address material testing for properties in the fresh and hardened states. Fresh properties include slump spread, filling ability, passing ability, and air content. Hardened properties include compressive strength, modulus of elasticity, creep, shrinkage, chloride permeability, and freeze-thaw durability. Testing of the girders includes transfer length, end-slip, midspan deflections, midspan strains, and internal curing temperatures. Summaries and conclusions are provided along with recommended guidelines for implementation.
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