Technical regulations - CBS Concrete

Application of elements

Manure silo walls are designed for the construction of storage tanks for liquid manure, fermentation installations, water storage, water treatment tanks and the storage of wastewater.
The trench silo walls are designed for the construction of the storage locations for raw fodder, grain, sand, recycling waste, coal or other raw materials.
The retaining walls are designed to prevent ground movements, for instance with:
- Inclines
- Quay walls
- Sound screens
- Water reservoirs
- Bank reinforcements
- Pond construction

Explanation of abbreviations

C:	Elements provided by "CBS BETON"
L:	L-type retaining wall
T:	T-type retaining wall
U:	U-type retaining wall
X:	The maximum length of the formworks = 200 cm
XX:	The maximum length of the formworks = 400 cm
XXX:	The maximum length of the formworks = 600 cm
AGRI:	Agri-type retaining wall
LI:	Horizontal tank
BARD14:	14 cm thick wall panel
BARD20:	20 cm thick wall panel
S:	Silo wall
G:	The back side of the retaining wall is smooth
A:	The back side of the retaining wall has been levelled off. This gives a somewhat rougher finish than the G-type retaining walls.
Z:	Heel at the back side of the element.
HL:	Corner element - left
HR:	Corner element - right
VH:	Fixed corner
O:	Slip-over element
S:	For Agri-type walls, a support to at the backside.
KOMO:	The elements are delivered with a KOMO certificate: K42894 and K26806.
BODEM:	These elements are delievered in conformity with the "Soil Quality Ordinance" (NL-BSB-K26806).

Calculation specifications

A calculation is made for each standard element by the manufacturer. The calculations on the technical data sheets are based on the standards NEN 6702 and NEN 6720.

These calculations take the following factors into account:

Backfill: volumetric mass of a maximum of 18 kN/m³ and an internal angle of friction ƒ of minimally 30°. If the internal angle of friction ƒ is greater, then this is beneficial because the lateral pressure decreases. If the backfill is compressed, then this also has a beneficial effect, because the volumetric mass (approximately 15%) and the internal angle of friction become greater.. The actual internal angle of friction is dependent on the type of backfill. (See Art.. 3).
- The neutral earth pressure coefficient K0 amounts to 0.3755. This neutral earth pressure coefficient is used for the calculation of the sagging moment and for checking for cracks (GGT => gewone grenstoestand = normal limit).
- The active earth pressure coefficient Ka amounts to 0.5640. This active earth pressure coefficient is used for calculating the armouring (UTG => uiterste grenstoestand = outer limit).
The CUX and CUAGRI elements must be filled up at least for half of their height on the inside with earth.
Extra load:
Or:
- Mobile overload on the filling (ground level load): 10 kN/m²
- No backfill under a slope. The slope ß of the ground mass behind the retaining wall is 0°.
Or:
- No mobile overload on the backfill (ground level load): 10 kN/m²
- Backfill under a slope. The slope ß of the ground mass behind the retaining wall is 45°.
No groundwater. The structures are installed above ground.

Examples of backfilling with earth:

Type of earth	Mass kN/m³	ƒ min	ƒ max	Included in the calculation	Comment
Dry earth	14	30	40	Yes
Earth is naturally moist	16	45	45	Yes
Earth saturated with moisture	18	27	27	Yes
Dry sand	16.1	30	35	Yes
Wet-moist sand	18	40	40	Yes
Sand saturated with moisture	20	25	25	Yes	See comment 1
Dry loam	15	40	45	Yes
Wet loam	19	20	25	Yes	See comment 2
Dry clay	16	40	50	Yes
Wet clay	20	20	25	Yes	See comment 2
Dry gravel	18	35	40	Yes
Wet gravel	18.6	25	25	Yes
Loose rubble	18	45	45	Yes
Grain	8.7	31	31	Yes
Corn	8	28	28	Yes
Rice	8.7	33	33	Yes

Comment 1: Only permissible when no mobile load of 10 kN/m² is applied.

Comment 2: Only permitted if the element is anchored in the underground, in order to prevent that the element slips away.

The underground:
In the calculation, account is taken of an underground of kN/m² (=1 Kg/cm²). This is equivalent to a normal, sandy underground. It is better to position at the retaining walls on stabilised sand. However, the stabilised sand must contain at least a 75 kg of cement per cubic metre, and a compression strength of at least2 to 3 kN/mm³ must be achieved.

Quality guarantee

The elements are produced with self-compacting concrete (SCC). The great advantage of this is that the pores are smaller than in traditional concrete. This means that the concrete is smoother and has a more homogenous colour. Due to the finer structure, the wall is more acid-resistant and therefore has a longer operating life.
The concrete conforms to the standards NEN-EN 206-1 and NEN 8005 and has the following properties:
- Environmental class: XC4, XD3, XS1, XF4, XA3
- Concrete strength: C50/60
- Steel quality: FeB 500
- Concrete cover: 30 mm
- W/C ratio: 0.45
- Water absorption of an average 5%
We only work with the best raw materials. Our raw materials are KOMO or BENOR certified.
The reinforcing steel conforms to the standard NEN 6008, has a FeB 500 quality and is delivered with a KOMO products are difficult.

Product certification

The retaining walls have been delivered according to this principle by us for more than 10 years.
Most elements are produced with a KOMO certificate. This guarantees the quality of our elements, conforming to the standards BRL 5070 and NEN 7330.
The following attestations have been granted to us with a KOMO product certificate:
- K42894: "Construction elements made of concrete"
- K42673: "Concrete products for agriculture"
Elements that cannot be produced with a KOMO product certificate nevertheless conform to the "Soil Quality Ordinance" (NL-BSB-K26806).

Dimensional tolerances

Concrete elements are manufactured with the following dimensional tolerances:
- Length: +/- 5 mm
- Height: +/- 5 mm
- Width: +/- 5 mm
- Curvature: 1.4 mm per metre

Delivery conditions

The General Terms and Conditions of CBS Concrete are applicable to all offers and deliveries.
The delivery site must be easily accessible for a freight lorry with trailer (3 axles).
The customer must assure that a good foundation is available for the elements (normal sandy soil or stabilised ground surface).
If elements are unloaded under your own care, then extra unloading hours will be invoiced as of the second unloading hour.
If elements are unloaded or positioned with our own crane vehicle, then extra unloading hours will be invoiced as of the second unloading hour.
The client must make 2 persons available as assistants for positioning the elements
It must be possible for the crane vehicle to drive up adjacently to the foundation, and sufficient room must be available for propping up the vehicle with its support arms.
If you want to install the walls yourself, then we will gladly provide you with lifting hooks in exchange for a deposit fee per item. A credit note will be issued to you, when the lifting hooks are returned.
Elements, which are not yet 28 days old, may only be delivered when the concrete has reached 70% of the intended final strength.

Storage and trading conditions

During transport, storage and installation, the concrete elements must be handled in such a way that their quality is not negatively affected.
Concrete elements are lifted in the following way:
- At 2 points, for which a possible overhang does not exceed 1/4 of the length of the element.
- With the help of a special retaining wall clamp.
Driving over or on the concrete elements during assembly is not permitted.
Stacking of the concrete elements must be carried out as follows:
- Manure silo wall panels are stacked horizontally on loading blocks and free of the ground. A possible overhang may not exceed 1/4 of the length of the element.
- Trench silo wall elements are stacked on each other, free of the ground and on loading blocks.
When storing, the underground must be flat and have sufficient supporting strength.

User instructions for lifting systems

Hakron system
Attachment of a Hakron lifting hook on a concrete element.

Lifting a concrete element with a Hakron hook.
"Halfen" system
Attachment of and lifting a concrete element with a Halfen lifting hook.

Instructions for use

The elements may only be taken into use or subjected to loads, when the designed compression strength is reached
The concrete elements may be subjected loads according to the calculated specifications (see above).