BS ISO 19044:2015 pdf free

BS ISO 19044:2015 pdf free.Test methods for fibre-reinforced cementitious composites – load-displacement curve using notched specimen
It is desirable to use a testing machine furnished with closed-loop control based on CMOD or LPD. Closed-loop control is desirable but not mandatory if a steady load-displacement relationship can be measured after the peak load without rapid progress of fracture.
NOTE Closed-loop control may not be necessary for normal fibre- reinforced concrete that is an FRCC with 0.5 ~ 2.0 vol. % of fibre volumetric ratio, as it causes no abrupt drop of post-peak loads. However, rapid propagation of post-peak failure can occur similarly to plain concrete depending on the materials and size of fibres. In such a case, it is desirable to use a testing machine that provides closed-loop control in terms of CMOD or LPD. Nevertheless, it is sufficient if a stable load-displacement relationship can be maintained after the peak load. Tests are therefore also feasible using a testing machine that controls the crosshead displacement or a manually controlled testing machine if unstable failure can be avoided by appropriately repeating loading and unloading after the peak load. In any event, the absence of unstable failure should be confirmed. Unstable failure means the case that the load was abruptly dropped in the softening region.
In order to eliminate torsional action on the specimen, the loading block and one of the supports shall be rotatable around their axes in the direction coincidental with the specimen axis. Both supports shall be hinged supports having rollers. The supports shall be horizontally movable to avoid any restraint on the deformation until the specimen completely ruptures. For other apparatuses used in but not specific to this ISO, refer to ISO 1920-4.
NOTE Both supports should be movable, as the horizontal movement of the specimen is restrained at the loading block. Inserting multiple rods under both supports as shown in Figure 2 is a simple and effective solution for a movable mechanism. In order to ensure the absence of horizontal restraint, it is advisable to press the specimen lightly by hand before applying any load to confirm smooth movement of the specimen in the horizontal direction.BS ISO 19044 pdf free download.