to prevent cracks from entering the gas-holder. Weak... - Energy Biogas Biogas Digest Vol 2

to prevent cracks from entering the gas-holder. Weak and strong ring have been successfully

combined in the CAMARTEC design.

Figure 21: Construction of the weak/strong ring of a 16 m3,

Tanzania

Photo: Kellner (TBW)

Materials and construction

The weak ring consists of mortar of a mixture of sand, lime and cement (15:3:1). The top of

the weak ring restores the horizontal level. It is interrupted only by the inlet pipe passing

through. The strong ring rests on the weak ring and is the first layer of the upper part of the

hemispherical shell. It consists of a row of header bricks with a concrete package at the

outside. In case of soft or uncertain ground soil one may place a ring reinforcement bar in the

concrete of the strong ring. The brick of the strong ring should be about three times wider

than the brickwork of the upper wall. A detailed description of the weak/strong ring

construction can be found in Sasse, Kellner, Kimaro.