Author: Manoj Kotni KumarPublisher:
ISBN:
Category : Bridges
Languages : en
Pages :
Book Description
Optimized Aggregate Gradation for Bridge Deck Concrete with Limestone Aggregate
Author: Manoj Kotni KumarPublisher:
ISBN:
Category : Bridges
Languages : en
Pages :
Book Description
Optimization of Aggregate Gradation Combinations to Improve Concrete Sustainability
Author: Majella Anson-CartwrightPublisher:
ISBN: 9780494764121
Category :
Languages : en
Pages : 574
Book Description
By optimizing the packing of the combined aggregate gradations, the cement paste content needed to make concrete can be reduced, improving sustainability, cost, performance, durability, and workability. Optimization can be achieved using theoretical and empirical techniques, or waste concrete material as an intermediate size fraction. However, the potential for improvement is currently limited by prescriptive grading specifications that require meeting individual requirements for fine and coarse aggregates.From this study, using various optimization techniques, it was found that by inclusion of an intermediate sized aggregate material, a reduction in cement paste up to 16% is possible for 35 MPa and 50 MPa mix designs typically used in Ontario bridge decks. The aggregate materials used were a natural sand, and two crushed limestones of 19.0 mm and 6.7 mm maximum size. From these findings, recommendations are made for improving the current Ontario Provincial Standard Specification (OPSS) 1002 used for concrete aggregates.
Effect of Changes in Total Aggregate Gradation on Portland Cement Concrete Properties
Author: Steven M. CramerPublisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 56
Book Description
An Improved Aggregate Gradation for Tennessee Portland Cement Concrete Bridge Deck Mixtures
Author: Barry Neal WhittenPublisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 204
Book Description
Shrinkage and Durability Study of Bridge Deck Concrete
Author: Robert L. VarnerPublisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 194
Book Description
Effect of Fineness of Continuously Graded Coarse Aggregate on Properties of Concrete
Author: William O. TynesPublisher:
ISBN:
Category : Aggregates (Building materials).
Languages : en
Pages : 58
Book Description
Effects of Special Aggregate on Bridge Deck Overlay Frictional Properties
Author: Vernon J. MarksPublisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 18
Book Description
Evaluation of High Absorptive Materials to Improve Internal Curing of Low Permeability Concrete
Author: Norbert J. DelattePublisher:
ISBN:
Category : Bridges
Languages : en
Pages : 148
Book Description
Early age cracking of bridge decks is a national problem, and may substantially reduce service lives and increase maintenance costs. Cracking occurs when the tensile stress exceeds the tensile strength of the concrete. This is a time-dependent phenomenon, since both the stress and strength change at early ages. Moisture loss increases stress (with increasing shrinkage) and impairs strength gain. Internal curing is one method that has been suggested to reduce early age bridge deck cracking, particularly of concretes with low water to cementitious materials (w/cm) ratios. Many state highway agencies have implemented high performance concrete (HPC) for bridge decks. The low permeability of HPC is used to protect reinforcing steel and prevent corrosion. However, if the concrete cracks, then the protection may be greatly diminished. Transverse cracks due to concrete shrinkage allow water and corrosive chemicals to quickly reach the reinforcing steel causing corrosion and shortening the lifespan of the bridge deck. Reducing shrinkage cracking has been the focus of recent research into mitigation strategies. One unintended consequence of the use of high performance concrete may be early-age cracking. Field studies have shown that, in some cases, high performance concrete bridge decks have cracked less than a year after placement. The use of internal curing to reduce autogenous shrinkage was investigated in this study. One method of internal curing was through the use of coarse aggregates with high absorption capacities. Another method discussed is the use of a partial replacement of the fine aggregate with a structural lightweight aggregate with a very high absorption capacity. Bridge deck cracking is also affected by the nominal maximum size coarse aggregate. The effect on shrinkage with increasing size is discussed. ODOT's District 12, located in Northeastern Ohio, found in an investigation of 116 HPC bridge decks placed between 1994 and 2001 that bridges with little or no cracking used coarse aggregate with an absorption> 1 %, while 75 % of bridges with unacceptable cracking used coarse aggregate with absorption 1 %. This report discusses the laboratory investigation of the field results to determine the better ways to prevent bridge deck cracking-- internal curing or paste reduction by using an aggregate blend. The laboratory investigation found that the strongest effect on cracking was due to the replacement of a small maximum size coarse aggregate with an optimized coarse aggregate gradation. Increasing the coarse aggregate absorption level from
Influence of Fine-aggregate Grading on Properties of Concrete
Author: U.S. Army Engineer Waterways Experiment StationPublisher:
ISBN:
Category : Aggregates (Building materials).
Languages : en
Pages : 32
Book Description
Concrete, Cement, and Aggregate Research
Author: Publisher:
ISBN:
Category : Aggregates (materials)
Languages : en
Pages : 8
Book Description