General information
Singular continued concreting of reinforced concrete walls and walls of water tanks at long sections, however, requires certain knowledge of the properties of concrete and later rheologic influence on the behaviour of the entire structure. In terms of structure tightness, however, very important are additional concrete deformations that take place during the use of the structure, occurring due to concrete contraction and creep.
By virtue of complexity of rheologic effects and complicated mathematical procedures, as well as numerous assumptions of the threshold state to be made during the calculation of these parameters, they are often neglected in terms of strength calculations for structures. In such cases, the designer’s role is often limited to including maximum expansion joint spacings in the design, indicating the minimum reinforcement field and the guidelines to be fulfilled with respect to concrete layout and care.
Engineering practice shows, however, that such means are not always sufficient. The result is wearing of shields. The difficulty of achieving good seals, and sometimes of indicating of the proper leak spots, the emerged cracks, may reduce the usability of a structure and greatly increase its usage costs. From the practical standpoint, the following is worth quoting:
‘Prevention is better than cure’ with respect to repair of cracked shields. Seeking to limit uncontrolled reinforced concrete wall fractures, one available solution is weakening of the wall cross-section through creation of precisely positioned vertical cracks. The use of Besaflex type S induced crack piping additionally protects the created crack from penetration by pressing water using the labyrinth effect.
| Properties | Unit | Requirements | Tested per |
| External form | – | No cracks, rifts | Visual evaluation |
| Shore hardness | ˚Sh | 83±5 | PN-EN ISO 868:2005 |
| Stretch resistance | MPa | ≥ 9 | PN-EN ISO 527-2:1998 |
| Relative elongation at break | % | ≥ 200 | PN-EN ISO 527-2:1998 |
| Shear resistance | N/mm | ≥ 8 | PN- ISO 34-1:2007 |
| Low temperature behaviour, -20 ˚C, relative elongation at break | % | ≥100 | PN-EN ISO 527-2:1998 |
| Controlled crack inducer pipe | ||||||||
| Symbol | a [mm] | d [mm] | f [mm] | Wall width [mm] | Package [pcs./pallete] | Sales unit | Weight [kg/mb] | Art. no. |
| Type H1 L=3 m | 128 | 88 | 25 | 240÷350 | 100 | pcs. = 3m | 2,80 | SU-TU-RR-0-02357 |
| Type H1 L=4 m | pcs. = 4m | SU-TU-RR-0-02358 | ||||||
| Type H1 L=5 m | pcs. = 5m | SU-TU-RR-0-02359 | ||||||
| Type H2 L=3 m | 235 | 175 | 25 | 350÷500 | 50 | pcs. = 3m | 5,50 | SU-TU-RR-0-02360 |
| Type H2 L=4 m | pcs. = 4m | SU-TU-RR-0-02361 | ||||||
| Type H2 L=5 m | pcs. = 5m | SU-TU-RR-0-02362 | ||||||
| Type H2 L=7 m | pcs. = 7m | SU-TU-RR-0-02363 | ||||||
| Type H3 L=3 m | 110 | 60 | 25 | 170÷240 | 120 | pcs. = 3m | 2,00 | SU-TU-RR-0-02364 |
| Type H3 L=4 m | pcs. = 4m | SU-TU-RR-0-02365 | ||||||
| Type H3 L=5 m | pcs. = 5m | SU-TU-RR-0-02366 | ||||||
Usage
Hidroplasto controlled induced crack pipes should be used at sites under threat of influence of liquids under hydrostatic pressure or of groundwater, for which the formwork or concreting technology requires the works to be carried out along large wall sections. The induced crack pipe selection depends on the thickness and height of the component to be weakened. No joined pipes should be used, and no piping composed of short sections should be used either. The axial separation of the selected controlled induced crack pipes depends on the following formula:
where:
R – axial pipe spacing,
h – height of component to be weakened,
g – component thickness.