ISO/DIS 19044-2015 pdf free.Test methods for fibre-reinforced cementitious composites一Load-displacement curve using notched specimen.
This ISO nnnnn specifies the test method for the load-displacement curves of fibre-reinforced cementitious composites (FRCC) by three-point loading of notched prisms. The main purpose of this test is to evaluate the tension softening curve of FRCC.
NOTE Both crack mouth opening displacement (CMOD) and load point displacement (LPD) are specified as the displacement of load-displacement curves, but measurement of both may not be necessary. Either may be selected depending on the purpose of measurement.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Members of ISO and IEC maintain registers of currently valid International Standard.
Iso 1920-3: Testing of concrete – Part 3: Making and curing test specimens
Iso 1920-4: Testing of concrete – Part 4: Strength of hardened concrete
3 Definitions and symbols
3.1 Definitions
For the purposes of this document, the following terms and defntions apply.
3.1.1 ligament area above the notch subject to rupture.
3.1.2 notch cut for the initiation of fracture.
4.1 Geometry
Specimens shall be prisms of square cross section with a notch at the mid-length to a depth of 0.3 times of the specimen depth (D) as shown in Figure 1.
a) The specimen size shall be fixed with two types for the ease of operating as follows: 150×1 50×550 mm for
the fibre length exceeding 40 mm; and 100x100x400 mm for the fibre length of 40 mm or less.
b) The loading span (S) shall be 3D. The overall length of the specimen (L) shall be not less than 3.5D.
C) The notch depth (ao) and notch width (no) shall be 0.3D and not more than 5mm, respectively.
d) The maximum aggregate size should be less than 25 mm.
e) The reference direction of loading shall be perpendicular to the direction of casting of the specimen as described in Figure 1.
4.2 Fabrication of specimens
a) Moulds specified in ISO 1920-3, 5.2.1 shall be used.
b) FRCC shall be placed in one placing sequence without joints, with attention being paid to fibre orientation.
The internal vibrator and compacting rod/bar shall not be used.
c) The notch shall be cut using a concrete saw when the FRCC has developed sufficient strength.
NOTE The notch should be cut in one side of the specimen with respect to its position as moulded so that the specimen would be turned on this side for loading, with the casting surface being vertical. It is not necessary to cut the edges of the notch to specific forms, as the edge shape scarcely affects the test results.
d) Specimens shall be subjected to testing in a condition immediately after completion of the specified curing procedure.
e) The number of specimens shall be not less than six. The tolerances of specimens are土0.5% for a side of section, and土5% for the clear span length, respectively. The mass of each specimen shall be measured to the nearest 0.05 kg.
5 Test equipment
5.1 Testing machine
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.ISO/DIS 19044 pdf download.