What is the main performance test for a continuous mixer?

The primary test is the uniformity test (Clause 7.2), where the coefficient of variation for cement content in concrete samples must not exceed 10%.

What are the standard designated sizes for these mixers?

The sizes are designated based on output in m³/h, such as CCM 15, CCM 30, CCM 45, etc., as per Table 1.

What is the required accuracy for the material feeding systems?

The accuracy should be within ±2% for water and ±3% for cement and aggregates by mass (Clauses 5.4.1, 5.5.1, 5.6.1).

What material is specified for the mixing blades and drum liner?

The mixing blades and drum lining plates are required to be made of abrasion-resisting steel to withstand wear (Clause 4.3).

IS 2435

: 1971

Continuous Type Concrete Mixers - Specification

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This standard specifies the requirements for the materials, construction, and performance of continuous type concrete mixers. It covers various designated capacities and outlines the testing procedures to ensure the uniformity and quality of the concrete produced.

Specifies requirements for continuous type concrete mixers.

Quick Reference Values

Maximum Coefficient of Variation for Cement Content10 percent

Maximum Coefficient of Variation for Coarse Aggregate7 percent

Water Metering Accuracy± 2 percent

Aggregate Metering Accuracy± 3 percent

Cement Metering Accuracy± 3 percent

Key Formulas

CV = (σ / x̄) * 100 — Coefficient of Variation for performance test of concrete uniformity

Practical Notes

Continuous mixers are primarily used for large-scale projects requiring a constant supply of concrete, such as road pavements, canal lining, or mass concreting for dams.

The most critical aspect of this standard is the performance test (Clause 7), which ensures the mixed concrete is uniform. This is vital for maintaining consistent strength and durability in the final structure.

Unlike batch mixers common on building sites, these machines require careful calibration of their continuous feeding systems for cement, aggregate, and water to meet the specified accuracies.