Experimental Tests on Cement Mortars Manufactured with Hemp Flour

Currently, research and market needs are aimed at the production of more and more specific mortars and concrete with the best properties and mix design directed towards increasingly specific uses.

This research starts with a discussion on cement and aggregate assortments, which are the basic properties of mortars.

The choice of suitable additives able to correct the rheological, workability and resistance properties of the mixture is focused.

In this framework, the current research activity involves some experimental laboratory tests on cement mortars manufactured with hemp flour, intended as a “natural” additive. The aim is the search for any improvements given by the hemp flour to the physical and/or mechanical performances of the tested mortars.

Hemp flour, due to bonding properties, increases the compactness, and therefore, the resistance to environmental factors by the examined cement mortars. The rheological features of mixtures with different percentages of hemp flour, whose maximum water percentage absorbed was resulted to be 125%, were investigated. It was found that standardised sand reduces shrinkage phenomena of tested specimens. Moreover, the compression and bending moment behaviour of manufactured specimens was analysed with the aim of finding the optimal weight percentage of hemp flour to improve their mechanical performances.

The experimentation performed leads to several conclusions and interesting future developments. It was found that 3% is the best-weighted percentage of hemp flour to increase the mechanical properties of examined mortars made of standardised sand. As further developments, there is a need to identify the limit percentage of hemp flour to be added to the mixture, so as to avoid the decay of the mechanical properties. In addition, further experiments must be carried out on concretes, where the presence of gravel leads to improve the stability and mechanical resistance of the cement matrix.