Akademik Veri Yönetim Sistemi
FRONTIERS OF STRUCTURAL AND CIVIL ENGINEERING, cilt.1, ss.1-16, 2024 (SCI-Expanded)
One issue with layer application of roller compacted concrete (RCC) is the development of cold joints,
which can cause damage to RCC structures. In this study, fly ash was used in place of 0%, 20%, 40%, and 60% of the
cement or aggregate to examine the impact of interlayer cold joint formation on RCC mixtures. To promote cold joint
formation, the second layer was placed and compacted with a delay of 0, 60, 120, or 180 min after the first layer. Three
methods were tried for preventing cold joints from forming: one was to apply a bedding mortar to the interlayer, another
was to add a set retarder admixture, and a third was to spray an adhesion-enhancing chemical additive on the surface of
the first layer. Based on the 28 d specimens’ compressive and splitting-tensile strengths as well as the depth of water
penetration under pressure, the most effective method was found to be applying interlayer bedding mortar. Considering
180 min delayed layer castings, the splitting-tensile and compressive strengths of the control samples decreased by 31%
and 17%, respectively, while the strengths of mixtures applying interlayer bedding mortar decreased by 9% and 10%. In
addition, bedding mortar treatment decreased the water permeability by 59% compared to the control. Interlayer cold
joint decreased all mixtures’ moduli of elasticity, regardless of the age of the specimens. When the interlayer delay was
60 min, the modulus of elasticity decreased by 1%–4%. It was between 2% and 14%, and between 10% and 24% at 120
and 180 min for the interlayer delay. The longer the delay in placing the second RCC layer, the more detrimental the
effect of the cold joint. This effect was most noticeable on mechanical and permeability properties tested with applied
load or water pressure parallel to the cold joint, such as flexural and splitting tensile strengths and water penetration depth
under pressure.