PRESTRESSED HOLLOW CORE SLABS

Used as roof and intermediate floor formers in building the industrial, business and non-residential facilities and residential buildings.
AS Betoneks manufactures six different types of hollow core slabs. Panels with the heights of 150, 220, 265 mm (designation BEP) are manufactured using extruding method, i.e. the concrete mix is pressed around the hollow formers. Panels with the heights of 265, 320 and 400 mm (designation BVP) are manufactured using vibration technology, i.e. the concrete mix is vibrated around the hollow formers.

Meaning of symbols used in markings of AS Betoneks hollow panels:
BEP27/120-101-01
BVP27/120-101-01

B – first letter from Betoneks AS name
EP – prestressed extruded hollow core slabs
VP – prestressed vibrated hollow core slabs
K – console panel with prestressing tendons in the upper layer
T – panel with increased fire resistance and additional insulation
S – panel insulated underneath, insulation layer 50 ÷ 150 mm
27 – nominal thickness of a panel in full centimetres (cm), (265 mm)
120 – nominal width of a panel in full centmetres (cm), (1,200 mm), design dimension of the cut panel
-10 – number of cables in bottom surface (pcs), (08–8 pcs, add 0 in front)
1 – reference mark, to which the cable diameter of 9.3 mm is corresponding, or
0 – reference mark, to which the cable diameter of 12.5 mm is corresponding, or
01 – reference mark, sequential no. of a panel in design specification (in the order), as concerns the pits for apertures/cuts.

Kogu infot õõnespaneelidest – ET 03 0202-1380 vaata SIIT

Cross-sections and load and camber diagrams are given below for all hollow panels manufactured by AS Betoneks.

Prestressed hollow core slabs –  ET-3 0202-0958.

 SPECIAL PURPOSE PANELS
CONSOLE PANELS which in upper layer are reinforced with rated prestressed cables or wires can be used for diversifying the facade surfaces of buildings either for making balconies, verandas or other console structure elements. In actual exploitation conditions, the span between the supports and its load should be additionally considered. The support joint of the console end should also enable the deformations in this area. The bearing capacity of the console part can be increased by a reinforced concrete surfacing layer and/or by concreting reinforcement into joints and upper parts of the hollows. To achieve higher fire resistance, the ordinary concrete should be protected according to the requirements of ENV 1992-1-1 with mortar, gypsum application insulation or some other sprayable effective fire resistant covering which properties are similar to concrete or by using special filling materials in manufacturing concrete.

HOLLOW CORE SLABS WITH UNDERNEATH INSULATION
All hollow panels can be delivered with underneath foam polystyrene insulation (type R and J), the designer determines the thickness of the insulation material 50 ÷ 150 (170) mm.

DIFFERENTLY CUT HOLLOW CORE SLABS
In addition to standard panels it is possible to deliver BEP15, BEP22, BEP27 and BVP27 panels also:
? cut more narrow
? cut at a given angle.

QUALITY OF PANELS
Visible (bottom) surface of panels is cast against metal mould concrete surface corresponding to 2nd category requirements and is ready for finishing. Side surfaces of panels are not treated cast machine surfaces. To the bottom side of panels, ca 0.3 ÷ 0.5 m from their ends, 10 mm diameter drainage openings are drilled to enable flow of water from the hollows after precasting.

INSTALLATION OF PANELS
Hollow panels should be lifted near the ends and only minor negative moments are allowed, e.g. console overlappings up to 0.5 m. The console overlappings can be bigger (>1.5 m) only in case the reinforcement cables are also in the upper layer of the panel. Hollow panels should be lifted with special gripper with slings and lifting forks. Usual slings and loop slings can be used for lifting special panels. Safety chains should always be used in lifting with special gripper. They cannot be released before the panel is ca 10–20 cm above the installation place.

SMALL OPENINGS ABOVE HOLLOWS
Small openings (max up to 80% to the extent of the hollow width) can be drilled above hollows according to designers’ advice, provided that the proper protection layer of the concrete of the prestressed cables is maintained. Above the hollows, into cross-section of the panel (white area in the drawing) max of 3 openings can be made. By demolishing the edge rib, the openings not checked with calculations cannot be made into the support area (critical cut length considering the shear force is = ls + h/2 where ls is the support length of the panel.

Design works

Since 1999, AS Betoneks performs the construction design works (sub-contractor AS MSI Grupp).
Initial data from the client necessary for design works and councelling:
Shape drawing, standard loads, required fire resistance.