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

IS 12727: Scope - Key Specifications & Tables

Scope Summary:

• Applies to materials and methods for no-fines concrete test cubes.
• Includes specifications for cement, aggregates, mixing, and testing.
• References multiple Indian Standards (IS) for cement, aggregates, concrete practice, and testing.

Important Tables & Specifications

Table 1: Optimum Water-Cement Ratio & Strength for Various Mixes (Clause 5.2)

Note: Values are indicative; actual mix design should be verified on-site.

Key Dimensions (Clause 1.6)

• Rubber Gasket Thickness: 1.6 mm
• Air Vent Hole Diameter: 6 mm
• Bearing Plate: 147 mm square x 5 mm thick

Referenced Indian Standards (Annex A)

• IS 269: Ordinary and Low Heat Portland Cement
• IS 383: Coarse and Fine Aggregates for Concrete
• IS 456: Code of Practice for Plain and Reinforced Concrete
• IS 516: Methods of Test for Strength of Concrete
• IS 1199: Sampling and Analysis of Concrete
• IS 455, 1489: Other Cement Specifications

Summary Diagram: Mix Design Flow

flowchart TD
    A[Select Aggregate Size] --> B[Choose Cement:Aggregate Ratio]
    B --> C[Determine Optimum W/C Ratio (Table 1)]
    C --> D[Mix Concrete]
   

IS 12727: Referenced Indian Standards Summary

Clause 2.1 & Annex A list essential Indian Standards (IS) related to no-fines concrete:

Key Notes:

• These standards cover cement types, aggregates, concrete testing, mixing, placing, curing, and terminology.
• IS 456:1978 is the primary code for concrete design and practice.
• Testing methods (IS 516, IS 1199) ensure quality control.
• Use the latest editions and amendments for compliance.

Typical Application:

• For no-fines concrete, follow IS 12727 alongside IS 456 and IS 383 for mix design and quality assurance.

flowchart LR
    A[IS 12727] --> B[IS 456: Concrete Practice]
    A --> C[IS 383: Aggregates]
    A --> D[IS 269,455,1489: Cement Specs]
    A --> E[IS 516,1199: Testing Methods]
    A --> F[IS 1791: Mixers]
    A --> G[IS 6461: Glossary]

This structured approach ensures standard compliance and quality in no-fines concrete construction.

IS 12727: Definitions and Terminology - Key Points

• Reference Standards for Definitions:

  • IS 4845:1968 — Definitions related to hydraulic cement.
  • IS 6461 (Parts 1,2,5-10) — Glossary related to cement concrete, including aggregates, materials, formwork, mixing, properties, structural aspects, and testing apparatus.

• Important Specifications:

  • Rubber Gasket thickness: 1.6 mm
  • Air Vent Hole diameter: 6 mm
  • Bearing Plate size: 147 mm × 147 mm × 5 mm thick

• Annex A (Clause 2.1): Lists Indian Standards relevant to cement and concrete such as:

  • IS 269: Ordinary Portland Cement
  • IS 383: Aggregates for concrete
  • IS 456: Code of Practice for Plain and Reinforced Concrete
  • IS 516: Methods of test for strength of concrete
  • IS 1791: Concrete mixers
  • IS 7861: Extreme weather concreting practices

• General Notes:

  • All dimensions in millimeters.
  • Use the definitions and terminology from the referenced IS codes for consistent understanding.
  • The standard ensures quality via BIS certification and continuous inspection.

Summary Table of Key Dimensions

Conceptual Diagram: Reference Flow for Terminology

graph LR
A[IS 12727 Terminology] --> B(IS 4845: Hydraulic Cement)
A --> C(IS 6461 Parts 1,2,5-10: Cement Concrete Glossary)
B --> D(Definitions for Cement)
C --> E(Definitions for Aggregates, Formwork, Properties, etc.)

Use these references and dimensions as the base for understanding terminology and specifications in IS 12727.

IS 12727 - Materials: Key Formulas, Tables, and Specifications

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

• For maximum strength, each cement-aggregate mix has a unique optimum water-cement (W/C) ratio.
• Proper paste coating and point-to-point contact of aggregates are essential for strength.

Note: Values are indicative; verify with site-specific tests.

2. Material Specifications (Annex A)

• Cement types: Ordinary Portland Cement (IS 269), Portland Slag Cement (IS 455), Portland Pozzolana Cement (IS 1489).
• Aggregates: Coarse and fine aggregates as per IS 383.
• Concrete: Plain and reinforced concrete per IS 456.
• Mixers, testing, and curing standards also referenced (e.g., IS 1791, IS 516).

3. Typical Material Dimensions (Clause 1.6)

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

Summary Formula:

[ \text{Optimum W/C Ratio} \rightarrow \text{Max Strength for given Mix} ]

This ensures concrete strength and durability per IS 12727 guidelines.

IS 12727: Production and Control of Concrete - Key Points

1. Water Quality

• Use water conforming to Clause 4.3 of IS 456:1978 for mixing and curing.

2. Optimum Water-Cement Ratio (Clause 5.2)

• For a given cement-aggregate ratio, there is a unique optimum water-cement ratio (W/C) that yields maximum strength.
• Table 1 (below) provides typical W/C ratios and expected 28-day compressive strengths for various mixes using Portland cement.

3. Mix Design Principles

• Select cement, aggregate, and water so that:
  • Aggregate particles are fully coated with cement paste.
  • Coated coarse aggregates have point-to-point contact for good bonding.
• Avoid blocking interstices between aggregates with excess cement paste.

4. References for Further Control

• Follow IS codes for cement (IS 269, IS 455, IS 1489), aggregates (IS 383), and concrete practice (IS 456).
• Use proper batching, mixing, curing, and testing as per IS guidelines.

Summary: Use Table 1 for guidance on mix proportions and W/C ratios to achieve desired strength. Ensure water quality per IS 456, and proper coating and bonding of aggregates for durable concrete.

IS 12727 - Formwork Key Points & Specifications

1. Formwork Design (Clause 6.1)

• No-fines concrete exerts negligible hydrostatic pressure → lighter, economical formwork.
• Materials:
  • Wooden planking (with/without steel sheet lining)
  • Steel plates stiffened by steel angles.
• Must be properly fixed & stiffened to avoid bulging.
• Surface: Smooth, even joints; no on-site cutting/fitting/nailing.
• Modular units assembled by bolts, clips for quick erection/removal by unskilled labor.
• Surfaces contacting concrete coated with soap solution before pouring.
• Formwork removal: normally after 3 days.

2. Strength Parameters (Clause 11.5)

• fc = 28-day cube compressive strength.
• ±10% variation allowed.
• Compression failure ~ 0.5 × cube strength.

3. Other References

• Transporting, placing, compacting, curing: per IS 456:1978 Clauses 14.2.1 & 14.2.2.
• Air vent holes: 4 holes of 6 mm diameter (Clause 4).
• Conformity to IS 456:1978 Clause 14.3 for plain/reinforced concrete formwork.

flowchart TD
    A[Formwork Design] --> B[Material: Wood/Steel]
    A --> C[Lightweight due to no-fines concrete]
    A --> D[Modular units, no on-site nailing]
    A --> E[Soap coated surface]
    A --> F[Removal after 3 days]

Summary: Use lightweight, modular, stiffened formwork with smooth surfaces coated with soap solution, designed for low pressure from no-fines concrete, following IS 456 for handling and curing.

IS 12727: Key Guidelines for Transporting, Placing, Compacting, Curing & Workmanship

1. Transporting (Clause 7.1)

• Transport concrete without segregation or ingredient loss.
• Maintain workability; do not allow setting before placing.
• Avoid adding water on-site to regain workability.

2. Placing & Formwork (Clause 6.1)

• Use lightweight, economical formwork (wooden planks with/without steel lining or steel plates).
• Formwork must be stiff, smooth, and reusable.
• Inspect and approve formwork before concreting.
• Remove formwork after minimum 3 days.

3. Compacting

• Ensure full compaction to avoid voids.
• Use appropriate tools (vibrators) for uniform compaction.

4. Curing (Clause 4.3 & 5.2)

• Use water conforming to IS 456:1978.
• Maintain moisture for minimum 7 days to achieve strength.
• Proper curing prevents cracks and improves durability.

5. Workmanship

• Ensure uniform mixing and correct proportions.
• Use optimum water-cement ratio from Table 1 below.
• Avoid blocking aggregate interstices with excess paste.

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

IS 12727: Fixings and Provision for Services - Key Points

1. Wall Ties (Clause 7.5.3)

• Maintain floor-wall interaction using mild steel wall ties.
• Minimum sizes of two reinforcing bars for wall ties (Table 2):

• Wall ties must be continuous, not interrupted by windows spanning multiple floors.
• Overlap of hooked/spliced ties = 500 mm.
• Wall ties fixed to adjacent floor reinforcement or lintels.
• For window openings, place 2 bars of 10 mm diameter under sills, overlapping 500 mm on both sides.
• Concrete cover minimum = 50 mm; reinforce with 3 mm cement slurry coating to prevent corrosion.

2. Provision for Services (Clause 8.2)

• Plan services (holes, chases, ducts) before casting by inserting cores in shuttering.
• Avoid cutting hardened no-fines concrete to prevent damage.

3. Additional Notes

• Use adequate stirrups with wall ties in high-strength no-fines concrete walls.
• Refer to Fig. 1 for reinforcement details at window openings.

flowchart TD
    A[Planning Services] --> B[Insert cores in shuttering]
    B --> C[Cast Concrete]
    C --> D[No cutting after casting]
    E[Wall Ties] --> F[Size per Table 2]
    F --> G[Continuous ties, overlap 500 mm]
    G --> H[Fix to floor reinforcement or lintel]
    H --> I[Window reinforcement: 2x10mm bars under sill]

This ensures structural integrity and service accommodation per IS 12727.

IS 12727 - Plastering Key Specifications & Formulas

1. Plastering Layers & Thickness (Clause 9.1, Table 3)

• Total plaster thickness: 10 to 12 mm in two layers.
• Used for both internal and external walls.

2. Mortar Composition (Clause 9.2, Table 4)

• Lime quantity in first coat is 1.5 times cement by volume.
• Sand is measured by loose volume.

3. Water-Cement Ratio & Strength (Clause 5.2 & 5.4, Table 1)

• Use optimum water-cement ratio for maximum strength.
• Adjust mix based on stone ballast size (20 or 40 mm).

Summary:

• Plaster thickness: 10-12 mm in two coats.
• Mortar mix: Cement-lime-sand ratios vary by layer.
• Water-cement ratio: Critical for strength, varies with mix.
• Sand grading: Coarser for base, finer for finishing coat.

flowchart TD
    A[Wall Surface] --> B[1st

Precautions for Walling Work as per IS 12727

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

   • Place 2 bars of 10 mm diameter mild steel under window sills.
   • Bars should overlap window rebate by 500 mm on both sides.
   • Maintain a minimum concrete cover of 50 mm.
   • Treat reinforcement with a 3 mm thick cement slurry/paste layer to prevent corrosion and improve bond.

2. Wall Ties (Clause 7.5.3 & Table 2):

   • Wall ties maintain floor-wall interaction.
   • Use mild steel ties with sizes based on building length:

   Length of Building (m)	Min. Size of Two Reinforcing Bars (mm)
   10	10
   18	12
   35	14

   • Spread ties throughout walls; avoid interruption by windows spanning multiple floors.
   • Overlap hook/spliced ties by 500 mm.
   • Fix ties to adjacent floor reinforcement or lintel.

3. Construction Joints (Clause 7.5.1):

   • Bond between new and existing no-fines concrete is weaker.
   • Take special precautions at joints (e.g., roughen surface, use bonding agents).

4. Expansion Joints (Clause 7.5.2):

   • Provide expansion joints at 35 m intervals to prevent shrinkage cracks.

flowchart TD
    A[Walling Work Precautions] --> B[Window Opening Reinforcement]
    A --> C[Wall Ties]
    A --> D[Construction Joints]
    A --> E[Expansion Joints]
    B --> F[2 bars Ø10mm under sill]
    B --> G[500 mm overlap]
    B --> H[50 mm cover + 3 mm cement slurry]
    C --> I[Size per building length]
    C --> J[500 mm overlap of ties]
    D --> K[Surface prep & bonding agents]
    E --> L[Expansion joints every 35 m]

Summary: Reinforce window openings with 2 Ø10 bars, maintain proper cover, use wall ties sized by building length, ensure careful joint treatment, and provide expansion joints

IS 12727: Sampling and Strength Test of Concrete - Key Points

Sampling

• Concrete samples should be taken as per IS 1199:1959 (Methods of sampling and analysis).
• Samples must represent the entire batch and be taken immediately after mixing.

Strength Tests (Clause 11.5)

• Strength is primarily measured by 28-day cube strength (fc).
• Other strength parameters relate to fc as:

• Variation of ±10% is allowed.
• No-fines concrete compression failure occurs at ~50% of cube strength.

Sampling & Testing Standards Referenced

• IS 1199:1959 – Sampling and analysis of concrete.
• IS 516:1959 – Methods of test for strength of concrete.
• IS 456:1978 – Code of practice for plain and reinforced concrete.

Notes

• Cube size typically 150 mm × 150 mm × 150 mm.
• Curing as per IS 516 before testing.
• Test results guide quality control and mix design adjustments.

flowchart LR
    A[Concrete Batch] --> B[Sampling as per IS 1199]
    B --> C[Prepare Test Cubes]
    C --> D[Cure 28 days as per IS 516]
    D --> E[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]

This concise summary aids in ensuring compliance with IS 12727 for sampling and strength testing of concrete.

IS 12727: List of Referred Indian Standards

The standard references essential IS codes for materials, testing, and construction practices related to no-fines concrete:

Key Notes:

• These standards cover materials, mixing, testing, and construction practices.
• Refer to IS 456 for detailed concrete design and IS 516 for strength testing methods.
• IS 383 and IS 269 specify aggregate and cement quality respectively.
• IS 1791 governs concrete mixer requirements.

flowchart LR
    A[IS 12727] --> B[Material Specs]
    A --> C[Testing Methods]
    A --> D[Construction Practices]
    B --> B1[IS 269, 383, 455, 1489]
    C --> C1[IS 516, 1199]
    D --> D1[IS 456, 1791, 7861]

This structure ensures comprehensive guidance for no-fines concrete production and testing.