Work

Towards a test method for measuring soluble alkalis in supplementary cementitious materials

Year: 2026

Type: article

Abstract: Supplementary cementitious materials (SCMs) are often used in concrete to reduce the risk of alkali-silica reaction (ASR), primarily through alkali dilution and binding. However, the effectiveness of SCMs with high alkali content (e.g., Na 2 O eq > 3.0 wt.%) in ASR mitigation is of concern, as these alkalis may dissolve in concrete’s pore solution and elevate its pH. This study proposes and preliminarily evaluates a test method to quantify the soluble alkalis in SCMs. The method was applied to 14 SCMs, including natural pozzolans, coal ashes, and ground glass, to monitor their alkali release over a 180-day period. The test involves measuring soluble sodium in 1 M KOH host solution and soluble potassium in 1 M NaOH solution. Thermodynamic modeling confirmed that most released alkalis remain in solution, with minimal solid precipitation and alkali binding. Findings revealed that a significant portion of alkalis in SCMs is soluble, often exceeding the level identified by ASTM C311 Available Alkali Test.

Source: Materials and Structures

DOI: 10.1617/s11527-026-03086-5

Authors: Moe Sharbaf, Zhanzhao Li, Jan Olek, Sulapha Peethamparan, Farshad Rajabipour

Institutions: Pennsylvania State University, Purdue University West Lafayette, Clarkson University

Language: English

Topic: Concrete and Cement Materials Research

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,390

Funders: U.S. Department of Transportation, Federal Highway Administration