Concrete & its Technologies

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

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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

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

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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.