Lightweight Expanded Clay Aggregate (LECA)

LECA, as the name suggests, stands for "Lightweight Expanded Clay Aggregate" and is a product of processed inorganic materials that are granulated and fired at high temperatures. According to GB/T17431.1 standards, it includes both coarse lightweight aggregates like LECA and fine lightweight aggregates like ceramic sand. LECA particles possess a robust outer shell made of ceramic or glazed material, providing water resistance and gas retention properties, along with elevated strength.

The density of LECA itself is typically less than 1100 kg/m³, ranging from 300 to 900 kg/m³. Concrete made using LECA aggregates as its core material has a density of 1100 to 1800 kg/m³, corresponding to compressive strengths of 30.5 to 40.0 MPa. A distinctive feature of LECA is its solid external appearance concealing a multitude of micro-pores, contributing to its lightweight nature. For instance, the density of concrete incorporating 200-grade fly ash LECA is around 1600 kg/m³, significantly lower than the 2600 kg/m³ density of equivalent ordinary concrete, with a difference of 1000 kg/m³.

The LECA provided by Zezhong exhibits remarkable insulation properties due to its internal porosity, resulting in a thermal conductivity of 0.3 to 0.8 W/(m·K) for LECA concrete, which is 1 to 2 times lower than regular concrete. Thus, LECA-based structures offer superior thermal environments.

LECA seamlessly integrates insulation, seismic resistance, frost resistance, and fire resistance. Concrete blocks composed of LECA demonstrate more than four times the fire resistance of ordinary concrete. For the same fire resistance rating, the thickness of LECA concrete panels is 20% thinner than regular concrete. Moreover, LECA can be used to create refractory concrete with fire resistance below 1200℃. At 650℃, LECA concrete retains 85% of its strength at room temperature, compared to the 35% to 75% strength retention of regular concrete.