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Ground Tire Rubber (GTR) as a Component Material in Concrete Mixtures for Paving Concrete
This research was done to investigate if the problems associated with flexibility and temperature sensitivity (expansion and contraction) in roadway concrete pavements can be addressed by replacing some of the fine or coarse aggregate component with crumb rubber, specifically, Ground Tire Rubber (GTR). The research also intended to find out the general effects of adding the GTR to the conventional pavement concrete, in terms of the mechanical properties and workability, requiring several laboratory tests to be conducted as part of the study. Finally, the research was required to evaluate the practical implementation at a ready mix plant, of the proposed use of GTR as a component in the concrete. It was found from the study that the modulus of elasticity of concrete is reduced when GTR is used in concrete, thus the pavement concrete becomes more flexible. Based on the results of the tests for the coefficient of thermal expansion (CTE), it was not conclusive from this study, that adding GTR will significantly affect the expansion and contraction in the concrete pavement. Many valuable findings from this study include the following: the optimal content for GTR for use as a component in the paving concrete mixture is 15% by weight of the fine aggregate; at a water/cementitious ratio of 0.44, concrete with GTR of 15% by weight of the fine aggregate, using water-reducing admixtures, can achieve a 28-Day compressive strength of about 3000 psi as well as reasonable values of the flexural strength and split tensile strength; slump was observed to typically decrease with addition of GTR but use of the water-reducer will eliminate this problem; the unit weight of the GTR concrete is less than that of the conventional concrete; air content will always increase with addition of GTR to the concrete but the use of a defoaming agent will reduce the foam and air content; GTR concrete has a non-brittle mode of failure in compression and flexure; examining GTR concrete under the Scanning Electron Microscope (SEM) indicated that there is good bonding between the rubber particles and the cement matrix in the concrete; pretreatment of GTR by simple washing and drying may improve the compressive strength of the GTR concrete; GTR concrete has very good plastic and dry shrinkage attributes, with the ability to resist shrinkage cracking; the ready mix plant operations will require dry-safe storage of the GTR, customized packaging (bag sizes or bag material) of the GTR for convenient batching, and a less duration for mixing before placement (when compared to the 90 minutes mixing duration allowed for conventional concrete); the GTR concrete can be used in the following applications: Class I pavement; sidewalks; curbs and inlets; or applications where the compressive strength of 3000 psi or less is adequate and also where shrinkage may be a problem.
Ground Tire Rubber (GTR) as a Component Material in Concrete Mixtures for Paving Concrete
This research was done to investigate if the problems associated with flexibility and temperature sensitivity (expansion and contraction) in roadway concrete pavements can be addressed by replacing some of the fine or coarse aggregate component with crumb rubber, specifically, Ground Tire Rubber (GTR). The research also intended to find out the general effects of adding the GTR to the conventional pavement concrete, in terms of the mechanical properties and workability, requiring several laboratory tests to be conducted as part of the study. Finally, the research was required to evaluate the practical implementation at a ready mix plant, of the proposed use of GTR as a component in the concrete. It was found from the study that the modulus of elasticity of concrete is reduced when GTR is used in concrete, thus the pavement concrete becomes more flexible. Based on the results of the tests for the coefficient of thermal expansion (CTE), it was not conclusive from this study, that adding GTR will significantly affect the expansion and contraction in the concrete pavement. Many valuable findings from this study include the following: the optimal content for GTR for use as a component in the paving concrete mixture is 15% by weight of the fine aggregate; at a water/cementitious ratio of 0.44, concrete with GTR of 15% by weight of the fine aggregate, using water-reducing admixtures, can achieve a 28-Day compressive strength of about 3000 psi as well as reasonable values of the flexural strength and split tensile strength; slump was observed to typically decrease with addition of GTR but use of the water-reducer will eliminate this problem; the unit weight of the GTR concrete is less than that of the conventional concrete; air content will always increase with addition of GTR to the concrete but the use of a defoaming agent will reduce the foam and air content; GTR concrete has a non-brittle mode of failure in compression and flexure; examining GTR concrete under the Scanning Electron Microscope (SEM) indicated that there is good bonding between the rubber particles and the cement matrix in the concrete; pretreatment of GTR by simple washing and drying may improve the compressive strength of the GTR concrete; GTR concrete has very good plastic and dry shrinkage attributes, with the ability to resist shrinkage cracking; the ready mix plant operations will require dry-safe storage of the GTR, customized packaging (bag sizes or bag material) of the GTR for convenient batching, and a less duration for mixing before placement (when compared to the 90 minutes mixing duration allowed for conventional concrete); the GTR concrete can be used in the following applications: Class I pavement; sidewalks; curbs and inlets; or applications where the compressive strength of 3000 psi or less is adequate and also where shrinkage may be a problem.
Ground Tire Rubber (GTR) as a Component Material in Concrete Mixtures for Paving Concrete
J. O. Sobanjo (author) / K. S. Tawfiq (author) / R. Twumasi-Boakye (author) / S. Inkoom (author) / S. Gibbs (author)
2015
123 pages
Report
No indication
English
Design of concrete paving mixtures
Engineering Index Backfile | 1929
|Design of concrete paving mixtures
Engineering Index Backfile | 1929
|Design of concrete paving mixtures
Engineering Index Backfile | 1929
|