Thermal analysis and adiabatic calorimetry for early-age concrete members

Abstract

This paper describes a procedure for thermal analysis on early-age concrete structures with experimentally obtained concrete adiabatic temperature rise and interface conductance between steel formwork and concrete. During hydration, concrete is considered in the analysis as non-homogeneous and the degree of hydration is dependent on both thermal loading and thermal properties development. A thermal convection model was implemented to simulate the external heat loss. Experimentally, two 1.2-m concrete cubes were constructed with embedded temperature sensors. The measured temperature time histories correlate well with the calculated values using a finite element model developed for this study. The modeling method and the experimental procedures developed are able to accurately predict the temperature evolution within an early-age concrete structure.

Mức độ thủy hóa và sự phát triển cường độ trong bê tông cường độ cao

“…Nghiên cứu của Schutter [6] chỉ ra rằng cường độ chịu nén tuổi sớm của bê tông thường có mối quan hệ tuyến tính với mức độ thủy hóa (). Sự tương quan tuyến tính cũng được kiểm chứng và khẳng định bởi nghiên cứu của Lin và Chen [15]. Tuy nhiên, đối với hỗn hợp bê tông cường độ cao có sử dụng hàm lượng chất kết dính và phụ gia siêu dẻo lớn thì chưa chắc hai đại lượng này có mối tương quan chặt như đối với hỗn hợp bê tông thường.…”

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].…”

Thermal Stress Analysis for Early Age Mass Concrete Members

“…The method developed can be used to estimate the thermallyinduced stress of concrete members so that precautions can be implemented prior to concrete cast in order to prevent unexpected cracking. The FEM stress analysis procedures were published in Lin and Chen (2015).…”

“…The hydration parameters, τ and β, were two constants depending on the mix design. τ = 14.0 and β = 0.94 were determined from the adiabatic temperature rise tests and curve fitting method as described in Section 5.2.2 and a published research paper by Lin and Chen (2015). were tested using the 15 cm × 30 cm (6 in × 12 in) cylinders and 10 cm × 20 cm (4 in × 8 in)…”

“…The variation of CTE of concrete is difficult to measure because of the temperature influence of the concrete maturity, especially at an early age; it was shown by McCullough and Rasmussen (1998) that concrete CTE variation after 24 hours of age could be assumed negligible where the CTE before 24 hours decreased noticeably. It is noted that CTE is also depending on the moisture level inside concrete, and it is assumed that the moisture level in the current concrete cube is close to 100% (Lin and Chen, 2015).…”