CONCRETE WALLS

• 1. Monolithic Reinforced Concrete Wall

1. Monolithic Reinforced Concrete Wall

The cast-in-situ reinforced concrete wall has excellent load-bearing properties, but its thermal performance does not meet the requirements without additional external thermal insulation. Regardless, entire buildings can be constructed with reinforced concrete walls, and it is also very common to use them only in structurally-crucial locations. The latter is particularly true for the shear walls and shafts of reinforced concrete frame buildings. Unlike infill walls, they are structurally closely integrated with other reinforced concrete structures.

Casting requires formwork that can be removable or retained, that is remains in place. The former is often referred to as a single layer construction, while the latter is a sandwich structure.

The traditional solution for formwork is to assemble the mould from wooden planks. A modern version is the factory-assembled wall formwork reinforced with metal frames and stiffeners. There are also tunnel, climbing and slipform formwork technologies.

The following is the technological sequence for the construction of a monolithic reinforced concrete wall with framed panels:

1. Clean the formwork and apply the formwork release agent
2. Assemble the front frame of the formwork on one side of the wall and support the structure with the push-pull props.
3. Place the additional frames in a row, support them and connect the framed panels with clamps.
4. Prepare, position and fix the reinforcement in the formwork.
5. Assemble the opposite side of the formwork, install the form-ties while adjusting the wall thickness and propping the formwork.
6. Carry out concreting as a single stage process, but in phases using concrete pumps and ready-mix concrete.
7. Compact the concrete after this.
8. Remove the formwork after two days of setting, but allow the wall 28 days to harden fully to the standard.
9. After removing formwork in concrete structures, it is essential to cure it to avoid cracks and strength problems.
   Therefore, the wall should be watered, damp, and protected from strong sunlight.

• 2. Shuttering Block Wall

2. Shuttering Block Wall

Concrete is also used to make small-block masonry. Due to concrete’s good structural properties but poor thermal performance, it is mainly used for basement walls, fence foundations, terrace plinth walls, etc. A special form of these masonry blocks is the concrete shuttering block.

The shuttering block wall is a semi-monolithic structure, a multi-layer poured wall where hollow blocks with an outer shell and ribs of about 3 cm are stacked in a dry state without any bonding material and then poured with concrete using them as permanent formwork. The concrete core is typically strengthened with a structurally-sized reinforcement, significantly increasing the load-bearing capacity of the wall. Masonry and casting is done in stages, typically 2 to 3 courses at a time.

It is advisable to use a half offset over the entire masonry, as this guarantees that the cavities are properly aligned, helping to ensure that the vertical bars are properly and evenly spaced. Alternating between half and whole shuttering blocks can be used to build the wall corner, the Tee connection, and the wall end. 

Construction of a shuttering block wall:

1. Eliminate any unevenness during the preparation of the supporting structure.
2. Mark the width of the masonry and the important nodes, and accurately set the height level with a tape measure.
3. If necessary, provide a damp proof or waterproofing course under the walls so that it can be continued once the wall is finished.
   The points of the setting are marked again on the waterproofing.
4. Place the starter course at the wall ends and wall corners, in 1-3 cm of perfectly levelled high-strength cement mortar.
5. Carry out masonry according to the general rules of wall bonding, laying the blocks without any mortar.
   The laying of the blocks should start at the wall-ends and wall corners.
   The horizontal reinforcement is placed continuously in the prepared grooves and in the vertical direction, in lengths of 80 to 100 centimetres, so to overlap the subsequent courses.
6. Before pouring concrete, care must also be taken to ensure that the blocks are sufficiently wet.
   Concreting, that is filling the cavities with concrete, is carried out every 2-3 courses.
   Concrete can be either mixed in-situ or ready-mixed.
   The former is typically cast with a shovel, and the in latter case the required quantity on concrete can be even pumped into its place.
   The poured concrete should then be compacted by tamping.
   To facilitate further construction, the top blocks should be filled only halfway with concrete.

• Practice 1

• Practice 2

• Practice 3

• Practice 4