Geosynthetics MCQ with answer and solution

Concept

Geotextiles are the most versatile geosynthetics, capable of simultaneously providing separation, filtration, drainage, and reinforcement functions.

Step-by-step solution

1. Identify the primary functions of each listed geosynthetic material. 2. Geogrids have large apertures; they function mainly as reinforcement and stabilization, not as filters or separators for fine soils. 3. Geonets have high planar transmissivity; their primary function is in-plane drainage. 4. Geomembranes are essentially impermeable sheet barriers used for containment and fluid control. 5. Geotextiles (woven or non-woven) possess tensile strength, appropriate pore openings, and permeability, enabling them to act as reinforcement, separation, filter, and drainage.

Explanation

Geotextiles are permeable geosynthetics that can perform all five major functions: separation, filtration, drainage, reinforcement, and protection/barrier (when coated or used as a composite). Geogrids are primarily used for reinforcement due to high tensile strength and interlocking with soil, but they cannot act as filters or separators of fine soils. Geonets are mainly used for planar drainage, and geomembranes are impermeable barriers used as liners/moisture barriers.

Why the other options are wrong

A: Geogrids have open grid-like structures and cannot function as a filter or separator of fine particles. B: Geonets are structured specifically for planar fluid transmission (drainage) and lack filtration/separation capabilities without a geotextile cover. D: Geomembranes are impermeable liners whose primary function is fluid barrier/containment, not filtration or drainage.

Shortcut

Geotextile is the multi-purpose 'fabric' that does all four: Separation, Filtration, Drainage, Reinforcement (SFDR).

Common mistake

Candidates often confuse geogrids with geotextiles; geogrids only reinforce because large aperture openings do not allow separation or filtration of fine soil particles.