Autogenous shrinkage in concrete is caused by self-dessication and occurs mainly in high strength concrete. This project investigates whether it is possible to use crushed concrete waste as an internal curing agent. The motivation is that in contrast to the production of lightweight aggregates (which are used) the reuse of concrete is a less energy demanding process.
Crushed concrete waste was sampled from the facility of RGS 90. The origin of the concrete waste was unknown. The fraction of the concrete waste passing the 2 mm sieve and retained on the 0.5 mm sieve was used for testing and for mixing in the concrete.
The compressive strength was seen to be unaffected by the addition of wet concrete waste product to the mortar. The desorption curve on the waste product was determined and found to be less optimal than lightweight aggregates for the purpose. The concrete waste material did not release enough water in regard to the demand in the American standard.
Finally, shrinkage measurements using a dilatometer did not show any effect of adding the waste product on reducing shrinkage. Overall, no evidence was found in this project that the actual concrete waste was suitable for use as internal water reservoir in high strength concrete. Further research could be done with other batches.
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