Masonry Deformability Properties Test
(Double Flat Jack Test)

In-situ determination of elastic modulus and deformability of existing masonry using the double flat jack test — essential for structural assessment and seismic retrofitting of historic masonry.

Overview

What is the Masonry Deformability Properties Test?

The Masonry Deformability Properties Test uses the double flat jack method to determine in-situ elastic modulus of masonry walls. Two flat jacks inserted in horizontal mortar joints are pressurised, and the resulting deformation measured to calculate elastic modulus — the primary structural parameter for masonry design and seismic assessment.

Conducted as per ASTM C1197, this test is essential for structural assessment of existing masonry — particularly historic structures and unreinforced masonry buildings evaluated for seismic retrofit. Global Lab conducts double flat jack tests as part of comprehensive masonry structural assessment.

In-Situ Elastic Modulus

Actual masonry modulus measured in the structure — not estimated from material tests.

Non-Destructive

Only small mortar joint slots cut — structure remains intact and functional.

Historic Masonry

Ideal for heritage and historic masonry where sampling is restricted.

Stress-Strain Curve

Complete load-deformation response of masonry in compression.

NABL Certified Reports

All results on NABL-accredited letterhead per ASTM C1197.

Seismic Assessment Input

Results used directly in IS 1893 seismic capacity assessment.

Test in Action

Masonry Deformability Properties Test — Site Images

Flat Jack Slots Cut in Masonry Joints

Flat Jacks Inserted with Reference Pins

Pressure-Deformation Curve Plotted

Test Procedure

How the Masonry Deformability Properties Test is Conducted

1

Slot Cutting

Two horizontal slots cut in masonry mortar joints above and below test section.
2

Flat Jack Insertion

Calibrated flat jacks inserted into slots. Reference pins installed for displacement measurement.
3

Pressure Application

Hydraulic pressure applied to flat jacks in increments. Pressure-deformation recorded.
4

Deformation Measurement

Relative displacement between reference pins measured by DEMEC gauges.
5

Elastic Modulus Calculation

Stress-strain curve plotted. Elastic modulus calculated. NABL report within 48 hours.

Standards & Specifications

Applicable Test Standards

Standard	Title	Scope	Type
ASTM C1197	Standard Test Method for In Situ Measurement of Masonry Deformability Properties Using the Flat Jack Method	Flat Jack Test	ASTM
ASTM C1196	Standard Test Method for In Situ Compressive Stress Within Solid Unit Masonry	Single Flat Jack	ASTM
IS 1905	Code of Practice for Structural Use of Unreinforced Masonry	Masonry Design	Indian Standard
IS 1893	Criteria for Earthquake Resistant Design of Structures	Seismic Assessment	Indian Standard

Applications

Where is the CAPO Test Used?

Structural assessment of aging and heritage masonry buildings

Seismic vulnerability assessment of unreinforced masonry (URM) buildings

Pre-retrofit characterisation of masonry for IS 1893 seismic assessment

Investigation of masonry buildings showing distress or differential settlement

Research on historic masonry material properties

Insurance and legal dispute masonry structural condition assessment

Why Choose Global Lab

Our Advantages

NABL Accredited ReportsLegally valid in-situ masonry elastic modulus certificates.

Heritage Building CapabilityMinimal intervention — suitable for listed and heritage buildings.

Seismic Assessment IntegrationResults used directly in IS 1893 seismic capacity calculations.

Pan-India CoverageNDT teams across all 7 lab locations.

Fast 48-Hour ReportComplete deformability assessment and NABL report within 48 hours.

Combined Masonry TestingFlat jack + Shear strength index + Rebound hammer as complete masonry assessment.

Masonry Deformability Properties Test(Double Flat Jack Test)