Early age strength development of GGBS concrete cured under different temperatures

Turu'allo, Gidion Early age strength development of GGBS concrete cured under different temperatures. Doctor of Philosophy thesis, University of Liverpool.

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Abstract

Concrete mixes incorporating ground granulated blast furnace slag (GGBS) has not gained popularity in fast track construction. It is believed to be due to its slower strength development at early age cured under standard curing temperature. The benefits that are obtained when using GGBS in concrete such as economic, sustainability and durability are discussed. Two grades of mortars/concretes i.e. C45 and C75 containing GGBS at levels of 0, 20, 35, 50 and 70% have been investigated to give guidance for their use in fast track construction. The effect of curing temperature on the strength development of mortars/concretes containing different levels of GGBS at early and later age have been investigated by testing strength of the mortars/concretes. The mortars were cured at 10, 20, 30, 40 and 500C and adiabatically cured conditions; while the concrete specimens were cured at 20 and 500C, as well under adiabatic curing conditions. The mortars/concretes were tested at age of 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256 and 365 days. There were also five mixes for lightweight concrete and three mixes for self compacting concrete that cast and cured under different temperatures of 20, 30, 40 and 500C, as well as under adiabatic curing conditions. This aims to evaluate the strength development of this kinds of concrete cured at different curing temperatures. The cubes were tested at the age of 0.125, 0.25, 0.5, 1, 2, 4, 7, 14 and 28-days. The heat outputs using of equivalent mortar mixes are measured using isothermal calorimeter. This is used to assess the temperature sensitivity of the strength development of GGBS concrete. It is also used to investigate the contribution of GGBS on the heat output produced in the hydration of binder. The accuracy of the existing maturity methods, which were developed based on concrete with Portland cement only, is evaluated to predict the strength of GGBS concrete investigated in this study. A new method, which is called Modified Nurse-Saul (MNS) method, is recently developed to predict strength development of concrete in this study. This method is used to predict the strength development of both Portland cement and GGBS concretes, as well as to predict the heat output development of equivalent mixes mortar. Finite element modelling was used to predict the temperature rise in concrete. Both the predicted heat output obtained from adiabatic test and isothermal calorimeter were used as heat sources. The predicted temperature is used to predict the strength development of concrete.

Item Type:	Thesis (Doctor of Philosophy)
Additional Information:	Date: 2013-06 (completed)
Uncontrolled Keywords:	GGBS concrete, maturity method, strength development
Subjects:	?? TA ??
Divisions:	Faculty of Science and Engineering > School of Engineering
Depositing User:	Symplectic Admin
Date Deposited:	11 Feb 2014 10:39
Last Modified:	16 Dec 2022 04:39
DOI:	10.17638/00012215
Supervisors:	Kougioumtzoglou, Ioannis Jones, Steve
URI:	https://livrepository.liverpool.ac.uk/id/eprint/12215