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.

Steel and polypropylene fibers result in a significant enhancement in strength, ductility, and toughness of concrete. This paper investigates experimentally and numerically the effect of these fibers on heat of hydration and early‐age cracking in mass concrete structures. Experimental investigations were conducted on evolution of strength, Young's modulus, and adiabatic heat rise in fly ash concrete mixes with steel and polypropylene fibers. Concrete mixes with ordinary Portland cement, 40% fly ash replacing the cement, 40% fly ash with 0.3 and 0.5% steel fibers, and 40% fly ash with 0.3 and 0.5% propylene fibers were investigated. The evolution of compressive and tensile strength, modulus of elasticity, and adiabatic heat rise using semi‐adiabatic calorimeter for all mixes was measured. The evolution of temperature at several locations in two full‐scale mass concrete blocks with normal concrete and fly ash concrete was measured. A multiphysics‐based finite element simulation of the two field mass concrete blocks was carried out using the software DIANA FEA BV (South Holland, Netherlands), which predicted the heat generation, temperature field, stresses developed in the blocks, and the associated cracking with good accuracy. The effect of steel and polypropylene fibers on heat, temperature, and stress generation in mass concrete blocks was investigated using the experimentally obtained parameters. The polypropylene fibers result in significant performance enhancement for early‐age cracking compared with the steel fibers.

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The palm and date sector is one of the most important sectors in Saudi Arabia. The total number of fertile palm trees in Saudi Arabia is about 31 million. In the production of pitted dates, date molasses, date paste, and date confectionery, a considerable number of date kernels are usually discarded as waste. This study reports experimental investigations conducted to evaluate the potential of waste date kernel ash (DKA), obtained by the calcination of date pits at 800 °C, as a partial cement replacement in concrete. DKA has low silica oxide and does not qualify as a pozzolanic material. The effect of DKA partially replacing the cement and acting as a filler material in concrete was investigated, and its properties were compared with two pozzolanic materials, fly ash (FA) and natural pozzolan (NP). Twelve concrete mixes in which cement was replaced with different proportions of calcined DKA (5%, 10%, 15%, 20%, and 30%), NP (10%, 20%, and 30%), and FA (10%, 20%, and 30%) were investigated in the experimental program. The properties of DKA, FA, and NP concrete mixes were evaluated in fresh and hardened states, including the heat of hydration, mechanical characteristics, and thermal properties. The results show that replacing cement with 5% date kernel ash increases the compressive strength by 0.42%, 3.2%, and 2.5% at 3, 7, and 28 days, respectively, while the 28-day compressive strength decreases by 2.4%, 5.4%, 16.3%, and 26.69% when the cement is replaced with 10%, 15%, 20%, and 30% DKA, respectively. Date kernel ash concrete mixes with 10%, 20%, and 30% replacement levels demonstrated higher compressive and tensile strengths and lower thermal conductivity, density, and workability when compared to natural pozzolan and fly ash. DKA is a promising partial cement replacement material; nevertheless, additional research is required to assess the durability of DKA in concrete.