Hydration, Pore Development and Chemical Resistance of Metakaolin - Fly Ash - Portland Cement (MK-PFA-PC) Blends
type: CreativeWork
description: The aim of the project is to utilise fly ash (PFA), a waste material / industrial byproduct, with metakaolin (MK), as a partial replacement for Portland cement (PC) in mortar and paste. The influence of various compositions of MK-PFA-PC blends on the resistance to the action of sulphate and synthetic seawater solutions, setting time and heat of hydration will be examined. MK is calcinated clay and is a relatively new pozzolanic material. Although it is a very effective pozzolan it is also very expensive. Using FA, which is a much less expensive material, as a PC replacement material, is problematic, as there is slow and low early strength development whereas MK enhances early strength development. Combining these materials in ternary blends should therefore produce a high performance material at an acceptable cost for use as a pozzolan. However the properties and performance of such a material still need to be fully established. The results of the research show, for the initial and final setting time of binary MK-PC pastes there is a substantial increase at 5% MK and then decreases at 10 and 15% MK before increasing again at 20% MK replacement level. However, with PFA there are different trends to those observed when using MK alone. The initial and final setting time of binary PFA-PC pastes shows a slight increase at 10% PFA and then systematically increases with increase in PFA content up to 40% PFA. Evaluation of sample preparation for porosimetry found that, overall, the compression tested samples show a lower proportion of 'fine pores' (volume (%) 0.05) µm than the cored and cut paste disks. It is deducted that this is due to the widespread microcracking during failure of the cubes under compressive loading thus modifying the pore structure present in the compressive tested samples. In strength development of mortar there is very little advantage in using MK over binary PFA-PC mortar blends when exposed to sulphate solution for up to 2 years. The strength behavi…
abstract: The aim of the project is to utilise fly ash (PFA), a waste material / industrial byproduct, with metakaolin (MK), as a partial replacement for Portland cement (PC) in mortar and paste. The influence of various compositions of MK-PFA-PC blends on the resistance to the action of sulphate and synthetic seawater solutions, setting time and heat of hydration will be examined. MK is calcinated clay and is a relatively new pozzolanic material. Although it is a very effective pozzolan it is also very expensive. Using FA, which is a much less expensive material, as a PC replacement material, is problematic, as there is slow and low early strength development whereas MK enhances early strength development. Combining these materials in ternary blends should therefore produce a high performance material at an acceptable cost for use as a pozzolan. However the properties and performance of such a material still need to be fully established. The results of the research show, for the initial and final setting time of binary MK-PC pastes there is a substantial increase at 5% MK and then decreases at 10 and 15% MK before increasing again at 20% MK replacement level. However, with PFA there are different trends to those observed when using MK alone. The initial and final setting time of binary PFA-PC pastes shows a slight increase at 10% PFA and then systematically increases with increase in PFA content up to 40% PFA. Evaluation of sample preparation for porosimetry found that, overall, the compression tested samples show a lower proportion of 'fine pores' (volume (%) 0.05) µm than the cored and cut paste disks. It is deducted that this is due to the widespread microcracking during failure of the cubes under compressive loading thus modifying the pore structure present in the compressive tested samples. In strength development of mortar there is very little advantage in using MK over binary PFA-PC mortar blends when exposed to sulphate solution for up to 2 years. The strength behavi…
author: Snelson, David
language: eng
keywords: fly ash, PFA, metakaolin, MK, Portland Cement, PC, Mortar and paste, Hydration
date published: 2005-5
date modified: 2026-07-24T04:38:53Z
provider: University of South Wales
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of South Wales