Properties of LECA® LWA


Grain size

Leca® LWA is produced in to the form of a round shaped pellet with a ceramic resistant exterior skin and a porous and lightweight interior nucleus. The optimum grain size distribution can be extracted in function of the specific application. The grading of Leca® Lightweight Expanded Clay Aggregate most suited for geotechnical applications is 10-20mm for its lightweight, free draining and insulating properties whilst concrete block and panel production will usually use a 4-10mm or finer material such as 2-4mm or 0-5mm for a smoother faced application.


Depending on the grain size distribution the dry, loose bulk density of Leca® Lightweight Expanded Clay Aggregate ranges between 250 and 450 Kg/m3. To give example, whilst the average dry bulk density of 10-20mm is around 265kg/m3, it is usual for geotechnical application that the installed and compacted long term, freely drained mass is calculated using an installed density of 500kg/m3 allowing for the addition of moisture that has absorbed in to the pellets.


Leca® Lightweight Expanded Clay Aggregate offers a frictional resistance without any cohesion. The internal friction angle is very high for a rounded material with the average at 37° - 39° and the stiffness measured during load plate testing is exceptional for a lightweight material.

Thermal conductivity

The practical thermal conductivity may vary between 0,10 - 0,14 W/mK, depending on grain size, compaction, humidity level and type of technical solution.


Leca® Lightweight Expanded Clay Aggregate is totally inert, it contains no harmful substances or gases and is absolutely neutral. Its resistance to chemicals is comparable to that of glazed tile or glass. Its longevity is expected to be in excess of 100 years.