The 1976 edition of IS 8142 outlines a standardized technique to determine concrete's initial and final setting times by assessing the penetration resistance of mortar extracted from the concrete mix. This method is crucial for engineers to monitor concrete hardening both onsite and in laboratories, aiding decisions such as formwork removal and subsequent layer placement. The standard applies to concrete with a slump above zero and details specimen preparation, test scheduling, and documentation protocols.
Overview
The 1976 edition of IS 8142 outlines a standardized technique to determine concrete's initial and final setting times by assessing the penetration resistance of mortar extracted from the concrete mix. This method is crucial for engineers to monitor concrete hardening both onsite and in laboratories, aiding decisions such as formwork removal and subsequent layer placement. The standard applies to concrete with a slump above zero and details specimen preparation, test scheduling, and documentation protocols.
Audience
Contents
Structure
IS 8142 defines the procedures for assessing the setting behavior of concrete through penetration resistance measurements.
Key Details:
Concrete Mix Information:
Admixture Information:
Properties of Fresh Concrete:
Handling of Specimens:
Testing and Documentation:
Sample Reporting Table:
| Parameter | Values |
|---|---|
| Cement Type & Proportion | e.g., OPC 43%, PPC 57% |
| Aggregate Size & Grading | 20 mm, well graded |
| Water-Cement Ratio | 0.45 |
| Admixture & Percentage | Superplasticizer, 0.5% |
| Air Content (%) | 2.5% |
| Consistency (Slump) | 75 mm |
| Mortar Temperature (°C) | 25 |
| Ambient Temperature (°C) | 27 |
| Test Date | DD/MM/YYYY |
A process flowchart illustrates steps from concrete mix data to report creation, ensuring uniform testing as per IS 8142.
This section defines key terms associated with penetration resistance testing of concrete mortar, including specimen types, testing conditions, and units of measurement (N/mm² or kgf/cm²).
Reporting must include:
Test data presentation requires plotting penetration resistance (vertical axis) against elapsed time (horizontal axis) with specified scaling standards.
Specimens must be stored at prescribed test temperatures, covered with impermeable material to prevent moisture loss, and shielded from sunlight. Bleed water removal is only permitted during actual testing.
A conceptual graph shows the relationship between elapsed time and penetration resistance, ensuring measurement consistency.
IS 8142 specifies the apparatus needed for penetration resistance evaluation:
Penetration Resistance Devices:
Needles:
Calibration of spring-type apparatus should be conducted regularly.
Additional tools include a pipette for removing free water from specimen surfaces.
Specimens must be stored at test temperatures, covered with waterproof materials to prevent moisture loss, and shielded from sunlight.
Needle bearing areas and maximum lengths are tabulated for clarity.
Guidelines for preparing mortar specimens from concrete include:
Containers:
Tamping Rod:
Specimens should be stored in controlled environments to maintain suitable temperature and humidity, preventing drying or contamination prior to testing.
Reports should document concrete mix details, admixtures, air content, consistency, mortar and ambient temperatures, and testing dates.
A flowchart depicts the process from sieving and mixing to testing and reporting, ensuring uniform specimen preparation.
Instructions for specimen storage under IS 8142 include:
Containers:
Tamping Rod:
Storage Conditions:
A summary table outlines container and rod specifications along with storage prerequisites.
A flow diagram illustrates the storage procedure from specimen preparation to protection and maintenance.
IS 8142 mandates minimum specimen numbers and testing protocols:
Storage:
Testing:
A summary table and flowchart display specimen preparation, storage, testing, and criteria for test completion.
Key steps for conducting the test include:
Specimen Storage:
Specimen Numbers:
Report Contents:
Repeatability:
Equipment:
A process flowchart illustrates specimen preparation, storage, testing, and data recording to ensure proper handling and consistent results.
Penetration resistance is calculated using the formula:
Penetration Resistance (N/mm²) = Force required for 25 mm penetration (N) ÷ Needle bearing area (mm²)
Measurement Details:
Apparatus Specs:
Testing Protocol:
Graphical Representation:
A table summarizes needle areas, maximum force, and maximum achievable penetration resistance.
IS 8142 specifies precision and reproducibility criteria:
Precision:
Reproducibility:
Apparatus Requirements:
Test reports must include detailed concrete mix data, admixture content, air content and methods, consistency, mortar and ambient temperatures, and testing dates
A flowchart outlines specimen preparation, storage, testing, and evaluation ensuring reliable and repeatable setting time measurements.
The test report should comprehensively include:
Setting Times Defined by Penetration Resistance:
Graphing:
A summary table presents the penetration resistance values linked to initial and final set times.
This structured reporting ensures detailed documentation of concrete setting characteristics as per IS 8142.
Frequently Asked
To prepare mortar specimens according to IS 8142, first select a representative concrete sample sufficient to provide mortar to fill the test container to a depth of at least 140 mm. Next, sieve this sample through a 4.75 mm IS sieve onto a non-absorptive surface to separate coarse aggregates, retaining the mortar. Use rigid, watertight, non-absorptive containers with minimum lateral and height dimensions of 150 mm. Fill the container with the mortar and compact it using a tamping rod of 16 mm diameter and approximately 600 mm length with a hemispherical tip. This process ensures uniform, representative specimens for accurate penetration resistance testing.
Penetration resistance is determined by applying force to a needle penetrating 25 mm into the mortar specimen. The apparatus used can be spring reaction-type (50 to 600 N capacity) or hydraulic reaction-type (700 to 900 N capacity), with graduations not exceeding 10 N and accuracy of ±10 N. Needles have bearing areas of 645, 323, 161, 65, 32, or 16 mm² and are marked 25 mm from the bearing face to measure penetration depth. The penetration resistance (in N/mm²) is calculated by dividing the force applied (N) by the needle’s bearing area (mm²). Tests are conducted at least six times per hardening test, with readings spaced to create a smooth hardening curve, continuing until resistance reaches 26.97 N/mm² (275 kgf/cm²).
According to IS 8142, the initial setting time is identified when the mortar attains a penetration resistance of 3.43 N/mm² (35 kgf/cm²), while the final setting time corresponds to a penetration resistance of 26.97 N/mm² (275 kgf/cm²). These values are determined by conducting interval-based penetration resistance measurements on mortar extracted from concrete until the specified resistance thresholds are reached, ensuring consistent determination of setting durations.
The frequency of penetration resistance testing varies with mixture type and temperature. For typical mixes at normal temperatures, testing begins 3 to 4 hours after cement-water contact, followed by hourly tests. For accelerated mixtures or elevated temperatures, initial tests start 1 to 2 hours post-contact with shorter subsequent intervals. For retarded mixtures or low temperatures, initial tests may be delayed to 4 to 6 hours or more, then conducted at hourly or shorter intervals as penetration resistance increases. A minimum of six measurements are required until resistance reaches 26.97 N/mm² (275 kgf/cm²). Care must be taken to avoid repeated penetration near prior needle marks, maintaining spacing of at least twice the needle diameter or 13 mm.
IS 8142 recommends using either spring reaction-type apparatus with a capacity of 50 to 600 N or hydraulic reaction-type with 700 to 900 N capacity, both with graduations of 10 N or less and accuracy within ±10 N. Needles should have bearing areas of 645, 323, 161, 65, 32, or 16 mm²; the 16 mm² needle must not exceed 90 mm in length to prevent bending. Each needle’s shaft is marked 25 mm above the bearing face for consistent penetration depth measurement. Penetration depth should be 25 mm, applied over approximately 10 seconds, with needle impressions spaced at least twice the needle diameter apart and at least 25 mm from container edges. Penetration resistance is calculated by dividing the applied force by the needle’s bearing area, ensuring precise and repeatable mortar hardness evaluation.
Ask AI about any clause, requirement, or provision in IS 8142. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required