The quantity of steel fibres normally used has to be sufficient to ensure a continuous reinforcement inside the concrete matrix (normally the quantity goes from 25 to 60 kg/m³ and the corresponding volumetric percentage goes from 0,30% to 0,75%).
If we consider the same quantity and composition, fibres become more efficient according to a growing L/D aspect ratio (ratio of length to diameter),because the adherence between the two materials increases and as a consequence the fibre reinforcement improves its performances .Stressed fibres subjected to a tensile strength do not slip out easily.
It is important that fibres have, however, an aspect ratio L/D 50 or higher.
|Type of fibre||L/D Aspect Ratio|
|Art. LA GRAMIGNA 0,80 x 50||62,5|
|Art. LA GRAMIGNA 0,80 x 60||75|
|Art. LA GRAMIGNA 0,90 x 60||66,7|
|Art. LA GRAMIGNA 1,00 x 50||50|
The adherence to the concrete matrix improves also according to the fibre’s shape, the more fibres are shaped the more they are efficient. For this reason the steel fibres have hooked ends that allow a better anchorage into the cement matrix.
Picture of the fibre’s geometry
The use of the structural steel fibres La Gramigna turns out to be a cost-efficient and more convenient solution compared to the traditional reinforcement because it reduces the time needed for the laying process in the construction plant.
Fibres can be, as a matter of fact,put directly into the ready-mix truck , using suitable equipments to be loaded and to be disentangled. (see our Technical Data Sheet of the product SC99/3)