- 1. Classification of concrete
- 2. Concrete types and typical use cases
- 3. Mix design workflow (IS 10262:2019)
- 4. Durability criteria (IS 456:2000)
- 5. QA and testing
- 6. Troubleshooting
- 7. Emerging technologies
- 8. Codes and standards
- 9. Consultant checklist
- Disclaimer
Purpose: quick, consultant-ready reference for concrete systems, mix design, durability, QA, and troubleshooting. Use the TOC to jump to sections.
1. Classification of concrete
Basis | Types | Description |
By grade (strength) | M5 to M80+ | Nominal mixes up to M15. Design mixes from M20 upward. |
By density | Lightweight, normal, heavyweight | For insulation/structural/radiation shielding. |
By reinforcement | PCC, RCC, pre-stressed, post-tensioned | Defines load-carrying mechanism. |
By function | Structural, pavement, waterproof, shotcrete | Based on intended performance. |
By material system | Ordinary, HPC, FRC, polymer concrete | Driven by additives and design intent. |
2. Concrete types and typical use cases
Type | Grade | Typical mix / key parameter | Notes | Common applications |
PCC | M10–M15 | 1:3:6 / 1:4:8 | No steel. Compression only. | Levelling, blinding, bases. |
RCC | M20–M50 | Design mix | Steel for tension. General purpose. | Beams, slabs, columns, walls. |
Pre-stressed | M40+ | Low w/c, high strength | Tendons stressed before casting. | Bridges, long spans, girders. |
Post-tensioned | M40+ | Specialized mix | Cables stressed after strength gain. | Post-tensioned slabs, bridges. |
PQC | M40–M50 | Low slump 25–50 mm | Low w/c, dowel joints. | Highways, airports, industrial floors. |
IPS floor concrete | M20–M30 | 1:1.5:3 (modified) | Trowel-finished. Optional hardeners. | Warehouses, basements, parking. |
HPC | M60–M100 | w/b 0.25–0.35 | SCMs + SP for durability. | High-rise, bridges, coastal. |
FRC | M25–M50 | — | Fibres for crack control. | Flooring, tunnels, precast. |
SCC | M30–M70 | Flowing mix | No vibration. Complex rebar. | Precast, columns, congested zones. |
Shotcrete | M25–M45 | Dry / wet process | Sprayed application. | Tunnels, slopes, repair. |
3. Mix design workflow (IS 10262:2019)
Step | Parameter | Note |
1 | Select grade | Based on fck and structural need. |
2 | Target mean strength | fck + 1.65 × SD (site variability). |
3 | Water–cement ratio | Per IS 456 Table 5 (durability). |
4 | Cementitious content | Typically 300–500 kg/m³ by exposure. |
5 | Aggregate proportions | By size and grading (e.g., 60:40 CA:FA). |
6 | Admixture dosage | Trial for slump and strength. |
7 | Moisture correction | Adjust for absorption/free moisture. |
8 | Trial mixes | 3–4 iterations to finalize. |
Attached tool:
Ready Mix Concrete & Design Mix Systems
Ready Mix Concrete & Design Mix Systems
Concrete Durability and Testing Protcols
Concrete Durability and Testing Protcols
4. Durability criteria (IS 456:2000)
Exposure | Max w/c | Min cement (kg/m³) | Min grade | Remarks |
Mild | 0.55 | 300 | M20 | Residential floors. |
Moderate | 0.50 | 300 | M25 | Foundations, slabs. |
Severe | 0.45 | 320 | M30 | Basements, retaining walls. |
Very severe | 0.45 | 340 | M35 | Coastal exposure. |
Extreme | 0.40 | 360 | M40 | Marine, chemical plants. |
5. QA and testing
Test | Standard | Frequency | Objective |
Slump | IS 1199 | Every batch | Workability. |
Compressive strength | IS 516 | 7 and 28 days | Structural strength. |
Flexural strength | IS 516 | As required | Pavement design. |
Air content | IS 1199 | Lightweight concrete | Workability control. |
RCPT | ASTM C1202 | Periodic | Permeability/durability. |
UPV | IS 13311 (Pt 1) | Existing structures | Quality grading. |
Rebound hammer | IS 13311 (Pt 2) | NDT | Surface strength. |
6. Troubleshooting
Quick view of common failures and fixes
Issue | Observation | Root cause | Action |
Segregation | CA settles | High slump / poor grading | Reduce slump, correct grading, control vibration. |
Honeycombing | Voids at rebar | Inadequate compaction | Improve vibration, reduce max aggregate size or use SCC. |
Low strength | Cube failures | High w/c, poor curing | Audit w/c, mixing time, curing; redesign if needed. |
Cracks | Shrinkage/thermal | Poor jointing, high heat | Provide joints, limit heat, ensure curing. |
Scaling/dusting | Surface defects | Early finishing, poor curing | Finish after bleed water; cure well; consider hardeners. |
7. Emerging technologies
Type | Feature | Use case |
Geopolymer concrete | Alkali-activated binder | Sustainability-focused projects. |
Self-healing concrete | Autogenous/bacterial agents | Crack closure, durability. |
3D printable concrete | Extrudable yet structural | Prefab, robotic builds. |
CO₂-cured mixes | CO₂ mineralization | Lower embodied carbon. |
8. Codes and standards
Code | Description |
IS 456:2000 | Plain and reinforced concrete — code of practice. |
IS 10262:2019 | Concrete mix design. |
IS 383:2016 | Aggregates specification. |
IS 9103:2021 | Chemical admixtures. |
IS 516:2021 | Concrete testing. |
IS 1199:2018 | Workability tests. |
IS 3370:2021 | Water-retaining structures. |
IS 4926:2021 | Ready-mix concrete. |
ASTM C94 / ACI 211 | International mix design guides. |
9. Consultant checklist
- Select concrete type by structural need. Design mix for M20 and above.
- Set w/c per exposure; control permeability with SCMs and curing.
- Plan durability per IS 456 exposure class.
- Run trial mixes and lock admixture windows before production.
- Implement QA schedule: slump per batch, cubes at 7 and 28 days, periodic RCPT, NDT as needed.
Disclaimer
SpecX is a neutral, brand-agnostic resource based on standards and best practices. Cross-check with project requirements and local codes before finalizing specifications.