The development of indonesian local clay as a lightweight expanded clay aggregate (LECA) for organic growing medium

Abstract

Lightweight Expanded Clay Aggregate (LECA), a clay-based lightweight aggregate expanding after burning at high temperatures, is among the promising material since it can be used as construction materials for buildings and roads, geotechnical fillings, hydroponic growing medium, humidity control, wall damper, heat insulation, water treatment, and others. However, the potential of clay from various places in Indonesia used for LECA as an organic planting medium is still not explored considerably. In this paper, various local clays in Indonesia were studied to obtain a suitable clay as the single raw material for LECA production. Clay raw materials were originated from Purwakarta, Sukabumi, Klaten and Boyolali. The preliminary selection was evaluated based on XRD and XRF test results. The XRD and XRF analysis showed that Boyolali shale and Boyolali bentonite were the most fitted clay as single raw material for LECA production. Both materials were synthesized into LECA through a firing process at 1100oC and 1200oC. Furthermore, the LECA product was characterized by its bloating coefficient and water absorption. The best results were obtained by Boyolali bentonite with a bloating coefficient of 4.63 or can be referred to as medium type and 14.63% for water absorption.