Effects of LOI Content in Fly Ash on Shrinkage and Chloride Penetration Resistance of Mortars

Document Type

Article

Publication Date

1-1-2026

Abstract

This study aims to investigate the effects of high-LOI fly ash on the durability properties of concrete such as autogenous shrinkage, total shrinkage, and chloride penetration resistance. The artificial high-LOI fly ash with the desired LOI content was prepared by adding powdered activated carbon (PAC) to the original low LOI fly ash from the BLCP and Mae Moh power plants in Thailand, which had low CaO (1.31%) and high CaO (23.86%) contents, respectively. The LOI values of the artificial high-LOI fly ash were varied at 6%, 12%, 18%, and 30%. All tested specimens were prepared at a controlled flow of 110 ± 5% by using a superplasticizer with a water-to-binder ratio by weight of 0.5 and 30% fly ash replacement. Autogenous shrinkage, total shrinkage, and rapid chloride penetration tests (RCPT) were carried out. The test results revealed that autogenous shrinkage of mortar decreases as the LOI content in fly ashes increases due to an internal curing effect of the added PAC. In contrast, when the LOI increases, the total shrinkage of mortars increases due to increased porosity. Nevertheless, mortars with up to 15% LOI content in fly ash exhibit lower total shrinkage than OPC-only mixtures. It was also discovered that higher LOI content in fly ash reduced chloride penetration resistance. However, all tested fly ash mortar mixtures performed better than OPC-only mixtures.

Publication Title

Rilem Bookseries

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