Classification of building materials – laterite as a rock type In traditional civil engineering classification, laterite is best described as which type?

Introduction / Context:
Laterite is a widely occurring, highly weathered material rich in iron and aluminum oxides, commonly used for masonry blocks in tropical regions. Correctly classifying laterite helps in predicting its behavior, durability, and suitable uses in construction. Traditional exam-oriented classifications often align laterite with clay-rich (argillaceous) groups due to formation and behavior.

Given Data / Assumptions:

• We follow conventional civil engineering rock/soil classifications used in older building-materials texts.
• Laterite forms under intense chemical weathering in warm, wet climates.
• We focus on general textbook categorization rather than detailed geochemistry.

Concept / Approach:

Argillaceous materials are clayey or derived from fine-grained alumino-silicate weathering products. Laterite, though rich in oxides, often behaves like a clay-bound rock/soil when cut and used as blocks, especially before full hardening upon exposure. Consequently, many building-materials references list laterite under argillaceous types for practical purposes.

Step-by-Step Solution:

Verification / Alternative check:

Historic building practice in lateritic regions and older civil-engineering texts align laterite with argillaceous groups, differentiating it from calcareous (lime-rich), volcanic (extrusive igneous), or purely silicious (quartz-rich) rocks.

Why Other Options Are Wrong:

Volcanic rock: Laterite is residual, not igneous extrusive.

Calcareous rock: Laterite is not dominated by calcium carbonate.

Silicious rock: Although silica may be present, laterite is not categorized primarily as silicious in traditional building-materials exams.

Common Pitfalls:

Assuming laterite is a single uniform rock; overlooking its residual soil–rock continuum; confusing modern geochemical descriptions with exam-oriented categories.

Final Answer:

Argillaceous rock