Hasbi, President & CEO, Corniche India Pvt Ltd, Mumbai Self–compacting concrete can be defined as a category of High Performance Concrete that hasexcellent deformability in the fresh state and high resistance to segregation and can be placed and compacted under its self– weight without applying vibration.
For several years, the problem of the durability of concrete structures was a major topic of interest in the concrete industry.
The bridge superstructure is composed of five WF74G wide-flange, precast, prestressed concrete girders spaced at 6 ft 9 in. The main objectives of the IBRD program are to promote, demonstrate, evaluate, and document the application of innovative designs, materials, and construction methods in the construction, repair, and rehabilitation of bridges and other highway structures.
The use of SCC reduced production costs through faster placement and allowed for placement with fewer skilled workers.
One solution for the achievement of durable concrete structures independent of the quality of construction work is the employment of self-compacting concrete, which can be compacted in every corner of a formwork, purely by means of its own weight and without the need of vibrating compaction.
The necessity of this type of concrete was proposed by Okamura in 1986.
Raajesh Ladhad, Consultant, Structural Concepts, N. A number of projects since then have been executed around the world with a variety of application needs and requirements.
However, the gradual reduction in the number of skilled workers in the developed world, led to similar reduction in the quality of construction work.The South Dakota Department of Transportation (SDDOT) is interested in performing laboratory work to develop concrete mixture designs for SCC using crushed limestone (western South Dakota) and crushed quartzite (eastern South Dakota) coarse aggregate in the concrete.The concrete mixtures will be modified to allow for applications in precast and cast-in-place box culverts. Summaries of field applications by VDOT as well as lessons learned through implementation are included in the paper.The use of self-consolidating concrete (SCC) for the manufacture of precast structural elements provides the benefits of increased rate of production, reduced labor needs (safety), and enhanced product quality.The concrete properties, workability, ease of construction and performance would be monitored during construction of two precast and two cast-in-place box culverts. The goal of this research was to determine whether precast prestressed bridge elements with congested reinforcement could be cast using self-consolidating concrete (SCC) without vibration and yet comply with all parameters of strength, no honeycombing, and void-free surface finish.In precast applications, beams were fabricated with normalweight and lightweight SCC.In cast-in-place applications, drilled shafts, pier caps, and substructure repairs were cast with normalweight SCC.The bridge is 32 ft (9.8 m) wide and carries two lanes of traffic. The specifications required a slump flow of 25 to 28 in. The girders were lightly precompressed with twelve 0.6-in. (15.2-mm) diameter harped strands because WSDOT requires the use of the same type and number of girders in all spans of continuous bridges.The bridge was designed per the 4th Edition of the AASHTO LRFD Bridge Design Specifications. Self-Consolidating Concrete WDSOT received Innovative Bridge Research and Deployment (IBRD) funding from the Federal Highway Administration for the Tieton River Bridge.