Department of Architecture and Civil Engineering

Study of carbonation in novel lime based materials

At a glance

Funding body: EPSRC
Principal investigator: Richard Ball
Co-investigators: Pete Walker, Chris Bowen, Tim Mays
Researcher: Giovanni L.A. Pesce
Industry partners: Singleton Bird Ltd
Dates: 2010-2013

Abstract

Lime binders can absorb larger quantities of CO2 during setting compared to other products such as cement and are important materials for the restoration and conservation of historic buildings. They are commonly employed as binders for low carbon footprint fillers and industrial wastes.

Carbonation processes are well known but the mechanism in lime mixtures is poorly understood as is the influence of novel additives.

In lime binders, carbonation is one of the main reactions. In air lime it is the only one and it provides short and long term strength whereas in hydraulic limes, where other compounds (like C2S) provide strength in the short to medium term, carbonation contributes mainly long term strength. Therefore the role of carbonation depends on the type of lime: e.g. calcium lime, magnesiac lime, aerial lime with hydraulic additives and natural hydraulic lime.

This project investigates the carbonation mechanism in different types of lime and the influence of low embodied energy fillers and industrial wastes on the reactions. The mechanism is studied using electrochemical measurements (impedance spectroscopy) and the nature of carbonate formed will be characterised using a variety of electron optical and analytical techniques such as, environmental scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Models will be developed to describe carbonate dissolution and precipitation processes and water movement within the material.