NABL Accredited · Rock Testing
Point Load Strength Index of Cores(IS 8764:1998)
Point load testing of rock cores per IS 8764 — the rapid index test whose size-corrected Is(50) value correlates directly to UCS, enabling economical strength profiling along an entire borehole.
Is(50)
Size-Corrected Index
2–4 Days
Report TAT
NABL
Accredited
NABL Accredited Lab · ISO/IEC 17025:2017
Digital Reports via Autovity QLMS
Pan-India · 7 Lab Locations
Est. 2009 · 20,000+ Projects
Overview
What is the Point Load Strength Index Test on Cores?
The point load test (IS 8764:1998) loads a rock core between two conical platens until it splits, yielding a strength index in seconds rather than the machining-intensive days a UCS test requires. The raw index is corrected to the standard 50mm equivalent diameter — Is(50) — and correlates to UCS through well-established multipliers, making it the workhorse for strength-profiling long core runs where testing every metre by UCS would be uneconomical.
Global Lab performs diametral and axial point load tests on cores, applies the size correction, reports Is(50) with the strength anisotropy index where both orientations are tested, and flags invalid breaks per the standard's failure-plane criteria.
Reviewed by Mahemood Ahmad, Lab Manager — NABL Accredited Laboratory, Global Lab India
IS 8764 Method
Diametral and axial core testing with standard size correction to Is(50).
NABL Accredited
Index values valid for investigation reports and design correlation.
UCS Correlation
Is(50)-to-UCS conversion reported with the correlation basis stated.
Rapid & Economical
Strength profile along a full borehole at a fraction of UCS cost.
Anisotropy Index
Ia(50) reported where bedding/foliation direction matters.
Digital Reports
Certificates delivered via the Autovity QLMS dashboard.
Test Procedure
How the Point Load Strength Index of Cores is Conducted
- 1
Specimen Selection
Core pieces meeting the standard length-to-diameter requirements are selected along the borehole depth profile. - 2
Diametral / Axial Testing
Specimens are loaded between conical platens across the diameter (and axially where anisotropy is assessed) until failure. - 3
Validity Screening
Each break is checked against the standard failure-plane criteria; invalid breaks are discarded and noted. - 4
Size Correction to Is(50)
The measured index is corrected to the 50mm equivalent diameter using the standard correction. - 5
UCS Correlation & Profiling
Is(50) values are converted to estimated UCS with the stated multiplier and plotted against depth. - 6
Reporting
Index values, anisotropy ratios and depth profiles are issued via Autovity QLMS.
Standards & Specifications
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| IS 8764:1998 | Method for Determination of Point Load Strength Index of Rocks (Reaffirmed) | Test Method | Indian Standard |
| IS 9143:1979 | Method for the Determination of Unconfined Compressive Strength of Rock Materials (Reaffirmed) | Correlated Parameter | Indian Standard |
| ISRM SM | ISRM Suggested Method for Determining Point Load Strength | Supplementary Practice | International |
Applications
Where is the Point Load Strength Index of Cores Used?
Economical strength profiling of long core runs
Preliminary UCS estimation for feasibility studies
Weathering-grade delineation along boreholes
Field strength checks at remote investigation sites
Anisotropy assessment in bedded / foliated rock
Supplementing UCS programmes at close depth intervals
Why Choose Global Lab
Our Advantages
Borehole-Scale CoverageMany index points for the price of one UCS — better strength profiles.
NABL Accredited ReportsValid for investigation deliverables and design use.
Validity DisciplineInvalid breaks screened per standard — indices you can trust.
Stated CorrelationsUCS conversions always cite their multiplier basis.
Pan-India CoverageCore receipt and testing across our 7 lab locations.
Digital ReportingCertificates delivered via the Autovity QLMS dashboard.
Quick Answers
Frequently Asked Questions
What standard governs the Point Load Strength Index of Cores?
Point Load Strength Index of Cores is tested per IS 8764:1998, IS 9143:1979 and ISRM SM.
How long does the Point Load Strength Index of Cores take?
Reports are typically issued within 2–4 Days of sample receipt at the lab, delivered digitally via the Autovity QLMS client dashboard.
Where is the Point Load Strength Index of Cores used?
It is commonly used for economical strength profiling of long core runs, and for preliminary UCS estimation for feasibility studies.