Which type of CMU contains expanded shale, clay, and slate or pumice?

Lightweight CMUs (Concrete Masonry Units) are specifically designed to include lightweight aggregates such as expanded shale, clay, slate, or pumice. These materials are incorporated into the concrete mix to reduce the overall density of the blocks while maintaining strength. By using these lightweight aggregates, the resulting CMU is easier to handle and transport, making it particularly advantageous in construction where weight reduction is desired without sacrificing structural integrity.

In contrast, standard CMUs typically utilize heavier aggregates like gravel, which result in denser blocks. Heavyweight CMUs contain materials that enhance their density, making them suitable for specialized applications such as radiation shielding. High-density CMUs also focus on a high aggregate density but are not specified for the same lightweight materials as those found in lightweight CMUs. This understanding of the materials and their properties is critical when selecting the appropriate type of CMU for a specific construction application.