Which type of soil structure is unsuitable for construction purposes?

The type of soil structure that is considered unsuitable for construction purposes is massive soil. Massive soil has a dense and tightly packed arrangement of particles, leading to poor drainage and limited air circulation. This compact nature can result in inadequate support for structures, increased risk of water retention, and challenges in achieving proper compaction during construction.

In general, soil structures such as blocky and granular are more favorable for construction as they allow for better drainage and provide a more stable foundation. Blocky soil features angular aggregates that can interlock, offering good stability, while granular soil consists of larger particles that promote drainage and reduce swelling or shrinking during moisture changes. Columnar soil, characterized by vertical columns of soil particles, can also pose challenges, but it is primarily the massive structure that impedes construction by preventing necessary moisture movement and aeration.