Friday, September 11, 2015

Retaining Walls - Construction

A reinforced concrete base is cast with projecting steel bars accurately located for vertical continuity. The wall may be built solid, e.g. Quetta bond, with voids left around the bars for subsequent grouting. Alternatively, the wall may be of wide cavity construction, where the exposed reinforcement is wrapped in 'denso' grease tape for protection against corrosion. Steel bars are threaded at the top to take a tensioning nut over a bearing plate.

Staged post-tensioning to high masonry retaining walls

Retaining Walls - Masonry Units

These are an option where it is impractical or cost-ineffective to use temporary formwork to in-situ concrete. Exposed brick or blockwork may also be a preferred finish. In addition to being a structural component, masonry units provide permanent formwork to reinforced concrete poured into the voids created by:

- Quetta bonded standard brick units, OR
- Stretcher bonded standard hollow dense concrete blocks.

Masonry Units

Monday, September 7, 2015

Climbing Formwork or Lift Casting

This method can be employed on long walls, high walls or where the amount of concrete which can be placed in a shift is limited.

Cantilever Retaining Walls

These are constructed of reinforced concrete with an economic height range of 1200 to 6000. They work on the principles of leverage where the stem is designed as a cantilever fixed at the base and base is designed as a cantilever fixed at the stem. Several formats are possible and in most cases a beam is placed below the base to increase the total passive resistance to sliding.

Mass Retaining Walls

These walls rely mainly on their own mass to overcome the tendency to slide forwards. Mass retaining walls are not generally considered to be economic over a height of 1800 when constructed of brick or concrete and 1000 high in the case of natural stonework. Any mass retaining wall can be faced with another material but generally any applied facing will not increase the strength of the wall and is therefore only used for aesthetic reasons.