Sustainable Construction Materials

Sustainable Construction Materials – Study Notes

1. Why Sustainable Materials Matter

2. Classification of Sustainable Materials

3. Material‑Specific Overviews

3.1 Bamboo

• Growth rate: 3–5 m yr⁻¹; harvestable in 3–7 years.
• Properties: High tensile strength (~250 MPa), lightweight, flexible.
• Applications: Structural frames, flooring, panels, formwork.
• Sustainability notes: Carbon‑negative when responsibly sourced; requires treatment against insects and moisture.

3.2 Hempcrete

• Composition: Hemp shiv + lime binder + water.
• Thermal conductivity: 0.07–0.12 W m⁻¹ K⁻¹.
• Benefits: Breathable, moisture‑regulating, sequesters CO₂ during lime carbonation.
• Limitations: Low compressive strength (≈5 MPa); mainly used for infill walls, not load‑bearing.

3.3 Recycled Concrete Aggregate (RCA)

• Source: Crushed demolition concrete.
• Performance: Comparable compressive strength to natural aggregate when ≤30 % replacement; higher water absorption.
• Environmental gain: Saves ~20 % of natural aggregate, reduces landfill volume, cuts embodied CO₂ by ~5–10 %.

3.4 Geopolymer Concrete

• Binders: Fly ash, slag, metakaolin activated with alkaline solutions.
• CO₂ reduction: 70–90 % less than ordinary Portland cement (OPC) concrete.
• Strength: 30–80 MPa (depends on mix); good chemical resistance.
• Challenges: Alkali handling, limited commercial mix designs, early‑age shrinkage control.

3.5 Reclaimed Wood

• Sources: Demolished structures, old pallets, shipping containers.
• Advantages: Preserves historic character, reduces demand for virgin timber, lower embodied energy.
• Considerations: Must be inspected for rot, nails, contaminants; may require re‑finishing.