The ‘pull out’ resistance of LECA® Lightweight Expanded Clay Aggregate makes it an ideal solution for reinforced soil retaining walls and bridge design. Particularly when constructed over weak sub-soils or voids, this method has been proven to cut overall construction costs considerably. LECA® Lightweight Expanded Clay Aggregate is used extensively to reduce vertical loading.
Structures such as underground parking, tunnels or roof garden benefit greatly from the reduction in pressure and avoid additional costs of strengthening. Being light weight and round in nature, LECA® Lightweight Expanded Clay Aggregate can be transported and placed more easily than that of traditional fill in these difficult to access areas.
The ability to blow the Leca® Lightweight Expanded Clay Aggregate into hard to reach areas and in conditions where the ground may be delicate and unsafe for heavy access using heavier, more traditional material, makes Leca® Lightweight Expanded Clay Aggregate the ideal solution which has been invaluable to civil engineers across the UK.
(Video) LECA® Lightweight Expanded Clay Aggregate was instrumental in helping to develop the FARRRS Bridge Development. A critical bridge development in Doncaster required a 13 meter high bridge crossing over the East Coast Main Line where there was a 40 meter deep glacial filled channel.The design of the bridges, required extensive and detailed flood modelling to provide reassurance to the Environment Agency and the local drainage board that the resilience of that protective network would not be compromised. Innovative solutions had to be developed for embankment construction including the use of lightweight aggregates where LECA® Lightweight Aggregate was selected.
Reducing Soil Pressure
Earth pressure of fill soil affects a supporting structure on a boundary surface between the supporting structure and earth. Supporting structures loaded by earth pressure include among others, retaining walls, sheet pile walls, back fill of bridges, basement walls, and foundations. (See Queensferry Crossing Project)
(Video) LECA® Lightweight Expanded Clay Aggregate was used to develop the East Moor Bridge for Wakefield Council. The Leca® Lightweight Expanded Clay Aggregate runs behind the bridge abutment cill beams and is retained by sheet piled wingwalls at either end. For this project it was critical to complete this engineering project at speed - with time being a key factor - LECA® Lightweight Expanded Clay Aggregate provided the ideal solution through its lightweight properties and speed of delivery.
As a fill material, LECA® Lightweight Expanded Clay Aggregate can effectively decrease the earth pressure. Due to its lightness the vertical earth pressure impacting the structure is up to 75% lower that induced by the natural rock fill. Lower earth pressure enables optimized dimensioning of supporting structures; and therefore application of LECA® Lightweight Expanded Clay Aggregate as backfill in these circumstances is usually a cost-efficient solution.
When LECA® Lightweight Expanded Clay Aggregate is applied to decrease the earth pressure, the following design aspects shall be taken into account:
- Properties of underlying subgrade and its loading history
- Pore water pressure in subgrade soil
- Groundwater and/or perched water level and possible open water level
- Allowed settlements and displacement of structure and its vicinity
- Adjacent buildings and foundations
- Dead and live loads
- Construction reliability and feasibility of a structure
- Principles of earth pressure reduction by using LECA® Lightweight Expanded Clay Aggregate are shown in Figure 4.6. Diagrams of the lateral earth pressure on the retaining wall in relation to the depth for LECA® Lightweight Expanded Clay Aggregate and conventional soil fill are presented in different colours.
Figure 4.6. Lateral earth pressure produced by back fill on retaining wall in relation to depth. Lateral earth pressure of LECA® Lightweight Expanded Clay Aggregate is shown above; corresponding impact of the conventional soil material is indicated below.
We have a team of representatives in the UK with extensive experience and knowledge on utilising LECA® Lightweight Expanded Clay Aggregate on a variety of Structural and Geotechnical Civil Engineering projects.
For a free quote and consultation on LECA® Lightweight Expanded Clay Aggregate contact LECA® UK: