Construction materials terminology — What is “shingle” in the context of aggregates?

Introduction / Context:
Accurate material identification is crucial in civil works. “Shingle” is a traditional term used in construction to describe a specific type of coarse aggregate found in riverbeds and beaches, influencing grading, workability, and surface finish.

Given Data / Assumptions:

• Terminology based on common civil engineering practice.
• Focus on natural aggregate origin and texture.
• No mechanical processing assumed for shingle beyond washing/sieving.

Concept / Approach:
Shingle denotes smooth, rounded, water-worn pebbles typically sourced from riverbeds or shorelines. Their rounded shape affects interlock and workability compared to angular crushed stone like granite.

Step-by-Step Solution:
Identify origin: transported and abraded by water currents.Recognize texture: rounded, smooth surfaces due to rolling action.Classify: natural coarse aggregate known as shingle.

Verification / Alternative check:
Standard textbooks define “shingle” as water-worn pebbles distinct from crushed stone.

Why Other Options Are Wrong:
Decomposed laterite / Air-weathered rock: not specifically rounded water-worn pebbles.Crushed granite: angular, machine-produced aggregate.Clayey silt nodules: fines, not coarse pebbles.

Common Pitfalls:
Assuming any rounded stone is “gravel”; shingle specifically implies water-worn pebbles.

Final Answer:
Water-worn pebbles (river shingle)