Autogenous Strain of Cement Paste and Mortar
(Chemical Shrinkage — ASTM C1698)

Measurement of autogenous (self-desiccation) shrinkage of cement paste and mortar from initial set — critical for high-performance and low water-cement ratio concrete prone to early-age cracking.

Overview

What is the Autogenous Strain of Cement Paste and Mortar?

Autogenous Shrinkage is the volumetric change of cement paste after setting due to chemical shrinkage consuming water from capillary pores — causing self-desiccation. In HPC with low W/CM ratios (<0.40), autogenous shrinkage can be significant (200–400 microstrain) and is a primary cause of early-age cracking.

Conducted as per ASTM C1698, autogenous strain measurement uses sealed corrugated plastic tubes preventing any moisture exchange — providing pure autogenous measurement from initial set through 28 days. Essential data for HPC, UHPC and mass concrete mix design with cracking risk.

Sealed Measurement

Corrugated tubes prevent moisture exchange — pure autogenous measurement.

From Initial Set

Measurement begins from initial set — captures the most critical early-age period.

HPC Cracking Risk

Key test for HPC, UHPC and mass concrete crack risk assessment.

SCM Effect Evaluation

Quantifies effect of silica fume, GGBS, fly ash on autogenous shrinkage.

NABL Certified Reports

All results on NABL-accredited letterhead per ASTM C1698.

Combined with Drying Shrinkage

Autogenous + drying shrinkage measured together for total shrinkage profile.

Test in Action

Autogenous Strain of Cement Paste and Mortar — Site Images

Corrugated Plastic Tubes Sealed After Filling

Digital Dilatometer Measuring Length Change

Autogenous Strain vs Time Curve Plotted

Test Procedure

How the Autogenous Strain of Cement Paste and Mortar is Conducted

1

Paste/Mortar Preparation

Cement paste or mortar mixed at target W/CM ratio. Placed in corrugated plastic tubes immediately.
2

Initial Set Detection

Setting time determined using Vicat penetration test per IS 4031.
3

Zero Reference

Length measurement recorded at initial set — zero datum for autogenous strain.
4

Sealed Curing & Measurement

Sealed tubes stored at 23°C. Length change measured daily for 7 days then at 14 and 28 days using digital dilatometer.
5

Autogenous Strain Report

Strain vs time curve plotted. 28-day autogenous strain in μm/m reported. NABL report within 28 days.

Standards & Specifications

Applicable Test Standards

Standard	Title	Scope	Type
ASTM C1698	Standard Test Method for Autogenous Strain of Cement Paste and Mortar	Autogenous Shrinkage	ASTM
RILEM TC 181	Early Age Cracking in Cementitious Systems	Early Age Cracking	RILEM
ACI 231R	Report on Early-Age Cracking: Causes, Measurement, and Mitigation	Cracking Report	ACI
IS 516	Methods of Tests for Strength of Concrete	Concrete Testing Reference	Indian Standard

Applications

Where is the CAPO Test Used?

HPC mix design optimisation to minimise autogenous shrinkage and cracking risk

UHPC autogenous shrinkage characterisation

Mass concrete mix design — minimising total volumetric change

Research on internal curing effectiveness using lightweight aggregate pre-soaking

SCM effect evaluation — silica fume vs GGBS vs fly ash on autogenous shrinkage

Prestressed concrete mix — minimising pre-tensioning losses from shrinkage

Why Choose Global Lab

Our Advantages

NABL Accredited ReportsLegally valid autogenous shrinkage data for HPC research and project compliance.

Early-Age Cracking AssessmentResults used to predict and mitigate early-age cracking in HPC structures.

SCM OptimisationCompares multiple SCM options to identify lowest autogenous shrinkage combination.

Combined Shrinkage PackageAutogenous + drying + chemical shrinkage tested as a complete shrinkage profile.

Pan-India CoverageTesting at all 7 NABL-accredited lab locations.

HPC Expertise15+ years experience in HPC durability and shrinkage testing for infrastructure.

Autogenous Strain of Cement Paste and Mortar(Chemical Shrinkage — ASTM C1698)