Early age thermal cracking of mass concrete blocks with Portland cement and ground granulated blast-furnace slag

Abstract

Evolution of heat due to an exothermic reaction between cementitious materials and water plays a significant role in the temperature rise in mass concrete at an early age. The temperature gradient between the core of mass concrete and its surfaces leads to the development of thermal stresses and may cause cracking if these stresses exceed the evolving tensile strength of concrete. This paper presents the results of an experimental and finite-element investigation of heat generation and dissipation in full-scale mass concrete blocks 2 m × 2 m × 2 m in size. A concrete mix with 100% OPC and 70% cement replaced by GGBFS was used in these blocks. The temperature profile across the depth of the block was measured at the centre, side and corner of the block. A semi-adiabatic calorimeter was used to measure the heat of hydration of the two concrete mixes. Finite-element simulation of these blocks captured with good accuracy the measured evolution of temperature in the blocks. Numerical simulation was subsequently used to investigate the influence of the size of the blocks, placement temperature of concrete, ambient temperature, solar radiation and type of formwork on the temperature rise and the associated potential of cracking in the mass concrete blocks.

Influence of steel and polypropylene fibers on cracking due to heat of hydration in mass concrete structures

“…The heat of hydration of the six concrete mixes used in the experimental program was measured using the iQdrum (Quadrel Inc., Pittsburgh, PA) semi‐adiabatic calorimeter. Standard 150 × 300 mm concrete specimen was placed inside the iQdrum immediately after mixing the concrete.…”

“…Using three‐dimensional (3D) finite element modeling of mass concrete, a time‐dependent heat transfer analysis is carried out to predict the temperature field and the degree of hydration based on the adiabatic temperature or adiabatic heat of hydration data. This is followed by mechanical analysis to compute the thermal and/or shrinkage strains and associated stress . The numerical simulation coupled with experimental measurement of heat of hydration provides an approach to assess risk of cracking in mass concreting and enables one to select a suitable concrete mix design with a low risk of cracking prior to the start of the project.…”

Thermal Analysis of Mass Concrete Containing Ground Granulated Blast Furnace Slag

“…They found that the PCA and ACI 207.R methods provided poor predictions. More recently, finite-element and finite-difference have been used to predict the temperature development of mass concrete structures by modeling the heat generation measured in adiabatic or isothermal conditions [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

“…Analytical models originally proposed for binders with Portland cement have been adopted by researchers for concrete with GGBFS. Saeed et al modeled the temperature profile of concrete blocks with only Portland cement and with 70% GGBFS replacement [10]; the GGBFS FEM predictions had a larger error compared to experimental measurements especially at an early age. Since the prediction of the temperature time history is directly related to the estimation of a structure's cracking risk, it must be predicted accurately.…”

Evaluation of the Thermal and Shrinkage Stresses in Restrained High-Performance Concrete

“…on the residual stress development and cracking behavior of cement-based materials have been investigated with ring tests [29,30,31]. Nevertheless, the ring tests cannot account for the effect of early age temperature variation on the cracking potential of cement-based materials, i.e., the effect of thermal stress was not taken into account [32]. In order to investigate the effect of the thermal stress on the cracking potential of concrete, the temperature stress testing machine (TSTM) was adopted in many studies [19,20,33,34,35,36].…”