Soil behavior facts: Which of the following statements are true regarding porosity, organic matter, and specialty cements for chemically aggressive soils?

Introduction / Context:

Site investigations often reveal a mix of soil textures and chemical environments. Recognizing baseline truths about porosity, organic content, and material selection helps engineers choose appropriate foundation solutions and concrete mixes for durability and capacity.

Given Data / Assumptions:

• General properties of clay vs. sand matrices.
• Influence of organics on strength and compressibility.
• Use of specialty cements in aggressive environments.

Concept / Approach:

Clay minerals have plate-like particles and significant inter-plate voids, leading to higher typical porosities than dense sands. Organic matter interferes with particle bonding and increases compressibility, reducing bearing capacity. Aluminous cement (or other sulfate-resisting binders) is selected for chemically aggressive soils and groundwater to mitigate deterioration mechanisms (e.g., sulfate attack).

Step-by-Step Solution:

Verification / Alternative check:

Laboratory testing shows lower shear strength and higher compressibility for organic soils; durability standards recommend sulfate-resisting cements for aggressive exposures.

Why Other Options Are Wrong:

• Each individual statement reflects established geotechnical and materials knowledge; hence “All the above” holds.
• “None of these” contradicts well-known facts.

Common Pitfalls:

• Assuming high porosity always means low permeability; clays can be highly porous yet poorly permeable.

Final Answer:

All the above