In highway and rail structures LECA® LWA is commonly used as a light fill material to reduce subgrade settlement and to improve stability of structure and the surrounding area. It serves as a similar purpose when used in pedestrian and bicycle throughways, rail yards and different platform and embankment structures.
In the reconstruction of highways and railways LECA® LWA can be applied to repair settlement defects, to increase levelling and to improve bearing capacity. In addition, with the help of LECA® LWA road and rail embankments that require widening can be constructed with minimal effect due to increased loading to the existing structure.
WHEN PROPERLY PLACED AND COMPACTED THE MAXIMUM EXPECTED LONG TERM COMPRESSION (CREEP) OF THE Leca® Lightweight Expanded Clay Aggregate STRUCTURE IS < 2%.
With respect to the project design criteria, the LECA® LWA layer can be designed to fulfill several objectives at one time: to provide frost insulation, to block capillary water rise and to function as a drainage layer.
In areas prone to mining subsidence or where ground conditions contain natural sub-formation voids, drainage, culvert or tunnels and there is a danger of collapse, expensive techniques such as load transfer are often considered.
However, using LECA® LWA can eliminate these costs and considerably lighten the load to provide similar benefits to those when used in weak soil areas.
(Video) LECA® LWA was used to develop the East Moor Bridge for Wakefield Council. The LECA® LWA 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® LWA provided the ideal solution through its lightweight properties and speed of delivery.
When constructing over weak underground voids or soils with low bearing capacity, the load compensation method may be considered using Leca® Lightweight Expanded Clay Aggregate.
By extracting a volume of existing soil from beneath the new construction, the equivalent volume of LECA® LWA replacing that soil will reduce the load on the subformation by four times. By using LECA® LWA, extraction can be kept to a minimum in order to achieve nil settlement.
Leca® Lightweight Expanded Clay Aggregate IMPROVES THE STABILITY OF THE SOFT SOIL SUBGRADE BY REDUCING THE LOAD IMPACT.
When LECA® LWA is applied to improve stability; the following design aspects shall be taken into account:
Properties of underlying subgrade and its loading history:
- Pore water pressure
- Groundwater and/or perched water level and possible open water level
- Inclination of ground surface or soil layers and possible river bed located beside the structure
- Required safety factor of structure against collapse
- Dead and live loads
- Adjacent buildings and foundations
Principles of subgrade stability improvement by LECA® LWA are shown in Figures 1.1 and 1.2. Sliding surfaces emerged in a road embankment and stresses of a subgrade produced by rock fill and LECA® LWA fill are presented in different colors. Red lines indicate the sliding surface and subgrade stress created by conventional rock. Green lines show the sliding surface of the fill structure implemented with Leca® Lightweight Expanded Clay Aggregate and the additional stress impacting the subgrade.
We have a team of representatives in the UK with extensive experience and knowledge on utilising LECA® LWA on a variety of Geotechnical Civil Engineering projects.
For a free quote and consultation on LECA® LWA contact Leca® UK: