Semi-adiabatic Curing Test with Heat Loss Compensation for Evaluation of Adiabatic Temperature Rise of Concrete

2012 ◽  
Vol 19 (4) ◽  
pp. 11-19
Author(s):  
P L Ng ◽  
A K H Kwan
2011 ◽  
Vol 261-263 ◽  
pp. 788-795 ◽  
Author(s):  
P L Ng ◽  
W W S Fung ◽  
J J Chen ◽  
A K H Kwan

Condensed silica fume (CSF) is often added into concrete mixes to enhance the properties of concrete. However, the effect of CSF on the heat evolution and temperature rise of concrete is not clearly known. Test results in the literature are insufficient and sometimes contradictory to enable any conclusion to be drawn regarding the role of CSF in heat generation behaviour of concrete. Moreover, since the chemical reactions of cement and CSF both involve water and hence cement and CSF are competing with each other in reacting with water, the water to binder (W/B) ratio may affect the temperature rise characteristics of concrete. This paper reports an experimental study of adiabatic temperature rise of CSF concrete conducted at The University of Hong Kong. Five concrete mixes without CSF and 10 concrete mixes with CSF dosages at 5% and 10% were tested with the recently developed semi-adiabatic curing test method. The adiabatic temperature rise was obtained by applying heat loss compensation to the test results. It was found that the addition of CSF could suppress the adiabatic temperature rise of concrete. At the same time, the strength of concrete could be enhanced. Based on the experimental results, prediction formula and design chart of adiabatic temperature rise of CSF concrete were developed.


2010 ◽  
Vol 168-170 ◽  
pp. 570-577 ◽  
Author(s):  
P.L. Ng ◽  
I.Y.T. Ng ◽  
Wilson Wai Sin Fung ◽  
Jia Jian Chen ◽  
A.K.H. Kwan

Owing to the less exothermic pozzolanic reaction of pulverized fuel ash (PFA) compared to cement hydration, the addition of PFA can reduce the heat generation of concrete during its hardening. However, as the water to binder (W/B) ratio would affect the proportions of cement and PFA that could react with water, the conventional practice of determining concrete temperature rise solely based on the cement and PFA contents may not yield accurate estimations. An experimental programme was launched to investigate the adiabatic temperature rise of PFA concrete mixes. Seven concrete mixes without PFA added and 14 concrete mixes with PFA dosages at 20% and 40% were tested with the recently developed semi-adiabatic curing test method. The adiabatic temperature rise was obtained by applying heat loss compensation to the test results. It was found that the incorporation of PFA could suppress the adiabatic temperature rise by 4°C to 14°C. The test results revealed the dependence of adiabatic temperature rise on both PFA dosage and W/B ratio, whose combined effects can be accurately addressed via the prediction formula and design chart developed herein.


2022 ◽  
Author(s):  
Hai Zhu ◽  
Dhanushika Gunatilake Mapa ◽  
Catherine Lucero ◽  
Kyle A. Riding ◽  
A. Zayed

2021 ◽  
Vol 13 (5) ◽  
pp. 771-780
Author(s):  
Shou-Kai Chen ◽  
Bo-Wen Xu

The adiabatic temperature rise model of mass concrete is very important for temperature field simulation, same to crack resistance capacity and temperature control of concrete structures. In this research, a thermal kinetics analysis was performed to study the exothermic hydration reaction process of concrete, and an adiabatic temperature rise model was proposed. The proposed model considers influencing factors, including initial temperature, temperature history, activation energy, and the completion degree of adiabatic temperature rise and is theoretically mature and definitive in physical meaning. It was performed on different initial temperatures for adiabatic temperature rise test; the data were employed in a regression analysis of the model parameters and initial conditions. The same function was applied to describe the dynamic change of the adiabatic temperature rise rates for different initial temperatures and different temperature changing processes and subsequently employed in a finite element analysis of the concrete temperature field. The test results indicated that the proposed model adequately fits the data of the adiabatic temperature rise test, which included different initial temperatures, and accurately predicts the changing pattern of adiabatic temperature rise of concrete at different initial temperatures. Compared with the results using the traditional age-based adiabatic temperature rise model, the results of a calculation example revealed that the simulated calculation results using the proposed model can accurately reflect the temperature change pattern of concrete in heat dissipation conditions.


2010 ◽  
Vol 48 (12) ◽  
pp. 15-22
Author(s):  
E. Maruya ◽  
H. Misumi ◽  
T. Takahashi ◽  
E. Sakai

2011 ◽  
Vol 250-253 ◽  
pp. 445-449
Author(s):  
Li Wei Xu ◽  
Jian Lan Zheng

The hydration degree of binders and cement is investigated by measuring the adiabatic- temperature rise of concrete at low water-binder ratio with different fly-ash content. The results denote that, with a constant water-binder ratio, both of the hydration degree of binders and that of cement decrease with the increasing fly-ash content in the early stage. In a later stage, however, the hydration degree of cement increases with the increasing fly-ash content and the hydration degree of binders peaks when the fly-ash content is 35%. Fly ash is one of the mineral admixture of which high-performance concrete is made up. It brings down the rise of concrete temperature significantly and helps solve the problems of shrinkage and crack of concrete structure. Because the hydration mechanism in common concrete is different from that in concrete with low water-binder ratio, and the hydration environment is different between concrete and cement pastes, to determine the adiabatic-temperature rise of concrete directly conforms to the actual situation. The adiabatic-temperature rise, adiabatic-temperature-rise rate, hydration degree of both binders and cement are investigated by measuring adiabatic-temperature rise of concrete with different fly-ash content.


Sign in / Sign up

Export Citation Format

Share Document