Code of practice for no-fines cast in situ cement concrete
1989 Edition

Scope Overview

• Covers materials and methods for no-fines concrete including test specimens.
• Details specifications for cement, aggregates, mixing, and testing procedures.
• Incorporates references to relevant Indian Standards for cement, aggregates, and concrete practices.

Essential Tables

Note: These values serve as guidelines; site-specific mix validation is recommended.

Important Dimensions

• Rubber gasket thickness: 1.6 mm
• Diameter of air vent holes: 6 mm
• Bearing plate size: 147 mm × 147 mm × 5 mm thick

Referenced Indian Standards

• IS 269, IS 383, IS 456, IS 516, IS 1199, IS 455, IS 1489 among others

Mix Design Flowchart

flowchart TD
  A[Select Aggregate Size] --> B[Determine Cement to Aggregate Ratio]
  B --> C[Identify Optimum Water-Cement Ratio]
  C --> D[Prepare Concrete Mix]

Summary of Referenced Indian Standards

Key standards cited in IS 12727 include:

Notes:

• These standards cover material quality, testing, and construction processes essential for no-fines concrete.
• IS 456 is the principal standard for concrete design and practice.
• Testing protocols ensure compliance and durability.

Integrated Standard Usage Flow

flowchart LR
  A[IS 12727] --> B[IS 456: Concrete Practice]
  A --> C[IS 383: Aggregates]
  A --> D[IS 269, 455, 1489: Cement Specifications]
  A --> E[IS 516, 1199: Testing Procedures]
  A --> F[IS 1791: Mixer Specifications]
  A --> G[IS 6461: Terminology]

Key Definitions per IS 12727

• Terminology is aligned with IS 4845:1968 for hydraulic cement and IS 6461 (Parts 1, 2, 5-10) for concrete-related terms.

Critical Dimensions

Referenced Standards for Terminology

• IS 269, IS 383, IS 456, IS 516, IS 1791, IS 7861 among others

Summary Diagram

graph LR
  A[IS 12727 Terminology] --> B[IS 4845: Hydraulic Cement]
  A --> C[IS 6461 Parts: Concrete Glossary]
  B --> D[Definitions for Cement]
  C --> E[Definitions for Aggregates, Formwork, Properties]

Materials Overview

1. Optimum Water-Cement Ratio (Clause 5.2 & Table 1):

• Each cement-aggregate combination has a specific water-cement ratio that maximizes strength.
• Proper cement paste coverage and point contact between aggregates is crucial.

Note: Site-specific verification recommended.

2. Material Standards (Annex A):

• Cement types: Ordinary Portland Cement (IS 269), Portland Slag Cement (IS 455), Portland Pozzolana Cement (IS 1489).
• Aggregates as per IS 383.
• Concrete practices per IS 456.
• Additional references for mixers, testing, and curing.

3. Dimensions:

• Rubber gasket: 1.6 mm
• Air vent holes: 6 mm diameter
• Bearing plate: 147 mm square × 5 mm thick

Summary Equation

[ \text{Optimum Water-Cement Ratio} \Rightarrow \text{Maximizing Strength} ]

Production and Control Highlights

1. Water Quality:

• Use water complying with IS 456:1978 Clause 4.3 for mixing and curing.

2. Optimum Water-Cement Ratio (Clause 5.2):

• Unique water-cement ratio for each cement-aggregate combination yielding peak strength.
• Refer to Table 1 for typical values and compressive strength expectations.

3. Mix Design Principles:

• Ensure aggregates receive full cement paste coating.
• Maintain point-to-point contact between coated aggregates.
• Avoid excessive cement paste blocking voids.

4. Additional References:

• Follow IS 269, IS 455, IS 1489 for cement quality.
• IS 383 for aggregates.
• IS 456 for concrete practice.
• Proper batching, mixing, curing, and testing per IS standards.

Summary:

Use Table 1 to guide mix design and water-cement ratio. Ensure water purity and proper aggregate coating for durable concrete.

Formwork Requirements (Clause 6.1)

• No-fines concrete exerts minimal hydrostatic pressure, enabling lighter and cost-effective formwork.
• Suitable materials include wooden planks (with optional steel sheet lining) or steel plates reinforced with steel angles.
• Formwork must be securely fixed and braced to prevent deformation.
• Surfaces should be smooth with tightly sealed joints; avoid on-site cutting, fitting, or nailing.
• Modular formwork units assembled with bolts or clips allow rapid erection and removal by unskilled workers.
• Surfaces in contact with concrete are coated with soap solution before pouring.
• Removal of formwork is generally done after 3 days.

Strength Parameters (Clause 11.5)

• ±10% variation acceptable.
• Compression failure approximately 0.5 × cube strength.

Additional References

• Transporting, placing, compacting, and curing as per IS 456:1978 Clauses 14.2.1 & 14.2.2.
• Provision of 4 air vent holes of 6 mm diameter (Clause 4).
• Compliance with IS 456:1978 Clause 14.3 for concrete formwork.

Summary Flow

flowchart TD
  A[Formwork Design] --> B[Use Wood or Steel Materials]
  A --> C[Lightweight Due to Low Pressure]
  A --> D[Modular Units, No On-Site Nailing]
  A --> E[Soap Solution Coating]
  A --> F[Remove After 3 Days]

Guidelines for Handling No-Fines Concrete

1. Transportation (Clause 7.1):

• Transport concrete without segregation or loss of ingredients.
• Maintain workability; avoid premature setting.
• Do not add water on-site to regain workability.

2. Placement and Formwork (Clause 6.1):

• Use lightweight, economical formwork (wooden planks with/without steel lining or steel plates).
• Ensure formwork is rigid, smooth, and reusable.
• Inspect and approve formwork before concreting.
• Remove formwork after a minimum of 3 days.

3. Compaction:

• Achieve full compaction to eliminate voids.
• Employ suitable tools such as vibrators for uniform compaction.

4. Curing (Clauses 4.3 & 5.2):

• Use water complying with IS 456:1978.
• Maintain moisture for at least 7 days.
• Proper curing prevents cracks and enhances durability.

5. Workmanship:

• Ensure uniform mixing and accurate proportions.
• Use optimum water-cement ratios as per guidelines.
• Avoid filling aggregate voids with excessive cement paste.

Table: Optimum Water-Cement Ratio & Strength

Wall Tie Requirements (Clause 7.5.3)

• Mild steel wall ties ensure floor-to-wall connection.
• Minimum size of two reinforcing bars depends on building length:

• Wall ties should be continuous without interruption by multi-floor windows.
• Hooks or splices of ties must overlap by 500 mm.
• Ties are fixed to adjacent floor reinforcement or lintels.
• For window openings, place two 10 mm diameter bars beneath sills with 500 mm overlap on both sides.
• Maintain minimum concrete cover of 50 mm, and apply 3 mm cement slurry coating on reinforcement to prevent corrosion.

Service Provision (Clause 8.2)

• Plan for services such as holes, ducts, and chases before casting by incorporating cores in formwork.
• Avoid cutting hardened no-fines concrete to prevent structural damage.

Additional Recommendations

• Use adequate stirrups with wall ties where high-strength no-fines concrete walls are constructed.

Process Flow

flowchart TD
  A[Service Planning] --> B[Insert Cores in Shuttering]
  B --> C[Cast Concrete]
  C --> D[Avoid Cutting After Setting]
  E[Wall Ties] --> F[Size As per Building Length]
  F --> G[Continuous Ties with 500 mm Overlap]
  G --> H[Fix to Floor Reinforcement or Lintel]
  H --> I[Window Sill Reinforcement: Two 10 mm Bars]

Plastering Layers and Thickness (Clause 9.1)

• Total plaster thickness ranges between 10 and 12 mm.
• Applicable for exterior and interior walls.

Mortar Mix Ratios (Clause 9.2)

Note: Lime quantity in first coat is 1.5 times the cement volume.

Water-Cement Ratio and Strength (Clauses 5.2 & 5.4)

Summary

• Apply plaster in two coats totaling 10-12 mm thickness.
• Mortar composition varies between coats with different cement and lime ratios.
• Water-cement ratio is critical to achieve desired strength.
• Sand gradation is coarser for base coat and finer for finishing.

Reinforcement at Window Openings (Clause 10.0 & Fig. 1)

• Place two 10 mm diameter mild steel bars beneath window sills.
• Bars should overlap window rebates by 500 mm on both sides.
• Maintain minimum concrete cover of 50 mm.
• Treat reinforcement with a 3 mm thick cement slurry coating to prevent corrosion and enhance bonding.

Wall Ties (Clause 7.5.3 & Table 2)

• Wall ties should be distributed throughout the walls, avoiding interruptions by multi-floor windows.
• Hooks or spliced ties must overlap by 500 mm.
• Fix ties securely to adjacent floor reinforcement or lintels.

Construction Joints (Clause 7.5.1)

• The bond at joints between fresh and hardened no-fines concrete is weaker.
• Take measures such as roughening surfaces and using bonding agents to improve joint strength.

Expansion Joints (Clause 7.5.2)

• Provide expansion joints at intervals of 35 meters to control shrinkage cracking.

Summary Flow

flowchart TD
  A[Wall Construction Precautions] --> B[Window Opening Reinforcement]
  A --> C[Wall Tie Installation]
  A --> D[Construction Joint Treatment]
  A --> E[Expansion Joint Placement]
  B --> F[Two 10 mm Bars Under Sill]
  B --> G[500 mm Overlap]
  B --> H[50 mm Cover + 3 mm Cement Slurry]
  C --> I[Size According to Building Length]
  C --> J[500 mm Overlap of Ties]
  D --> K[Surface Preparation & Bonding Agents]
  E --> L[Expansion Joints Every 35 m]

Sampling Procedures

• Collect concrete samples following IS 1199:1959, ensuring samples represent the entire batch.
• Sampling should occur immediately after mixing.

Strength Testing (Clause 11.5)

• Primary strength evaluation is based on 28-day cube compressive strength (fc).
• Related strength parameters are proportional to fc as follows:

• Allowable variance is ±10%.
• Compression failure occurs at roughly 50% of cube strength.

Standards Referenced

• IS 1199:1959 for sampling and analysis
• IS 516:1959 for testing methods
• IS 456:1978 for concrete practice

Notes

• Typical cube size is 150 mm × 150 mm × 150 mm.
• Cure specimens as per IS 516 prior to testing.
• Test outcomes inform quality control and mix adjustments.

Testing Flowchart

flowchart LR
  A[Concrete Batch] --> B[Sample as per IS 1199]
  B --> C[Prepare Test Cubes]
  C --> D[Cure for 28 Days per IS 516]
  D --> E[Conduct Compression Test]
  E --> F[Calculate Strength Parameters]
  F --> G[Tensile = 0.12 × fc]
  F --> H[Flexural = 0.23 × fc]
  F --> I[Cylinder = 0.61 × fc]
  F --> J[Bond = 0.19 × fc]

Referenced Standards Overview

IS 12727 refers to the following Indian Standards critical for materials, testing, and construction methods:

Notes

• These standards ensure quality control in materials, mixing, testing, and construction processes.
• IS 456 and IS 516 are fundamental for concrete design and strength testing.
• IS 383 and IS 269 specify aggregate and cement quality requirements respectively.
• IS 1791 governs the specifications for concrete mixers.

Overview Diagram

flowchart LR
  A[IS 12727] --> B[Material Specifications (IS 269, 383, 455, 1489)]
  A --> C[Testing Procedures (IS 516, 1199)]
  A --> D[Construction Practices (IS 456, 1791, 7861)]