Page 28 - New Trends in Green Construction

Circular Economy
Table 1. Mortar mix proportions
Mortar RA (g) NA (g) CEM (g)
Admixture (g)
(w/c)t (w/c)e
-
-
-
-
-
MSIV MSIV1 MSIV2 MSIV3 MSIV4 MRIV MRIV1 MRIV2 MRIV3 MRIV4
3641 610 3641 610 3641 610 3641 610 3641 610
3335 - 610 3335 - 610 3335 - 610 3335 - 610 3335 - 610
-- 0.79 0.76
Air Entrainers & Plasticizers Air Entrainers & Water Retainers Set Retarding & Plasticizers Superplasticizers & Water Reducers
4.88 0.75 0.73 4.88 0.84 0.81 4.27 0.75 0.73
15.25 0.6 0.58 -- 1.26 1.04
Air Entrainers & Plasticizers Air Entrainers & Water Retainers Set Retarding & Plasticizers Superplasticizers & Water Reducers
4.88 1.23 1.01 4.88 1.32 1.1 4.27 1.32 1.1 15.25 1.09 0.87
3.
Results and conclusions
The Air Entrainers & Plasticizers admixture reduced the amount of mixing water, improved the workability, decreased the mechanical strength and increased the shrinkage of mortar. This admixture would not be advisable to produce mortars with recycled sand from CDW, at least with the dosage tested.
The Air Entrainers & Water Retainers admixture did not reduce the amount of mixing water, improved workability, reduced the mechanical strength and increased the shrinkage of mortars. This admixture would not be advisable to produce mortars with recycled sand from CDW, at least with the dosage tested.
The Set Retarding & Plasticizers admixture reduced the amount of mixing water, it was very effective in improving workability, slightly improved mechanical strength and slightly reduced shrinkage. At the doses tested, this additive would be recommendable to produce mortars with recycled sand from CDW.
The Superplasticizers & Water Reducers admixture was shown to be the most effective in reducing the amount of mixing water, although the use of recycled sand without without pre-saturating previously reduced the workability time, significantly increased the mechanical strength and decreased the shrinkage of mortars. This admixture in the doses tested could be a good option to improve the masonry mortar properties, although the aggregates should be used previously pre- saturated in order to improve the workability of the mixture.
4. Acknowledgment
The author would like to thank the BASF Construction Chemical Spain SL for providing the admixtures tested.
5. References
Ledesma, E. F., Jiménez, J. R., Ayuso, J., Fernández, J. M., & de Brito, J. (2015). Maximum feasible use of recycled sand from construction and demolition waste for eco-mortar production–Part-I: ceramic masonry waste. Journal of Cleaner Production, 87, 692-706.
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