Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Influence of Internal Curing on Properties and Performance of Cement-Based Repair Materials

Published

Author(s)

Dale P. Bentz, Scott Z. Jones, Max A. Peltz, Paul E. Stutzman

Abstract

Repair materials are playing an increasingly important role in the maintenance of our nation’s aging infrastructure. Understanding their properties and performance is critical to planning and executing appropriate repairs that will provide the requisite service life for critical systems and components. This study focuses on the dimensional stability of cement-based repair materials by examining the autogenous shrinkage of two representative materials, and its mitigation via the use of internal curing (IC). Three different IC agents are investigated in this regard: pre-wetted lightweight aggregates (LWA), a superabsorbent polymer-coated sand (PCS), and a superabsorbent polymer (SAP). Repair mortars with and without IC are also characterized via chemical shrinkage and setting time measurements, isothermal calorimetry, semi-adiabatic calorimetry, quantitative X-ray diffraction, and measurements of compressive strength, elastic modulus, shear slant bond, and drying shrinkage. As the IC agents have absorptions of pore solution that span two orders of magnitude, they have differing influences on mixture proportioning and subsequent performance. For the two materials investigated in the present study, the mortars using LWA to provide IC exhibited the highest compressive strengths and greatest relative reductions in autogenous shrinkage in comparison to the controls formulated without IC. Since a portion of the autogenous shrinkage in these repair mortars appears to be due to loss of internal restraint upon the dissolution of ettringite crystals (needles), the replacement of 5 % of the repair mortar with a limestone powder to stabilize a portion of this ettringite and further reduce the measured autogenous shrinkage was also investigated. For this application, a coarse (16 µm median diameter) limestone powder was found to be superior to a finer (2.2 µm) one in reducing autogenous shrinkage, while providing otherwise similar performance.
Citation
NIST Interagency/Internal Report (NISTIR) - 8076
Report Number
8076

Keywords

Internal curing, limestone powder, lightweight aggregate, repair materials, shrinkage

Citation

Bentz, D. , Jones, S. , Peltz, M. and Stutzman, P. (2015), Influence of Internal Curing on Properties and Performance of Cement-Based Repair Materials, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.IR.8076 (Accessed July 15, 2024)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created October 6, 2015, Updated November 10, 2018