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The tensile creep of concrete with supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) is investigated in this paper. A total of 21 series of tensile creep tests using dog‐bone specimens under uniaxial tensile loading have been carried out. The cement replacement rates considered were 30% fly ash, 40% and 60% GGBFS. The characteristic compressive strength of concrete was ranging from 25 to 100 MPa. The tests were conducted from the age of 2 days until 28 days. It is observed that the tensile creep of fly ash concretes was slightly lower than that of the reference mixtures without SCM. For GGBFS concrete, the higher the GGBFS content, the higher the tensile creep. Existing creep models, originally developed for creep in compression, could not predict the experimental tensile creep results. Thus, a new tensile creep model was proposed including creep prediction for concrete with fly ash and GGBFS. The new model was calibrated only for controlled environmental conditions (23°C and 50% RH) and has been validated by analyzing the development of concrete tensile stress in the restrained ring test. [ABSTRACT FROM AUTHOR]

The fatigue properties of dog‐bone‐shaped specimens of FV520B‐I base metal and the welded joint up to 109 cycles were obtained. The S–N curves of the dog‐bone‐shaped specimens were lower than that of the funnel‐shaped specimens, and the S–N curves of welded joint specimens moved downward compared with that of base metal specimens. For all types of specimens, cracks initiating from the surface matrix and cracks initiating from subsurface inclusions were the main cracking modes in the high cycle regime and the very high cycle regime, respectively. The Murakami model and the modified model were used to predict the fatigue strength at 109 cycles. The parameter D* = NG / Ns was used to characterize the competition of different cracking modes, and the expression of the critical radius rc was obtained. Combined with the Gumbel distribution curve of the inclusion size, the probabilities of subsurface cracking and surface cracking were obtained. Highlights: The VHCF properties of dog‐bone‐shaped specimens of FV520B‐I were tested.The effects of specimen shape and welding on the VHCF behaviors and mechanisms were analyzed.The VHCF strength was predicted by Murakami model and the modified model.The parameter D* = NG / Ns was used to characterize the competition of different cracking modes. [ABSTRACT FROM AUTHOR]

Abstract In recent years, the pre-notched or pre-cracked small punch test (P-SPT) has been successfully used to estimate the fracture properties of metallic materials for cases in which there is not sufficient material to identify these properties from standard tests, such as CT or SENB specimens. The P-SPT basically consists of deforming a pre-notched miniature specimen, whose edges are firmly gripped by a die, using a high strength punch. The novelty of this paper lies in the estimation of fracture properties using dog-bone-shaped specimens with different confinement levels. With these specimens, three confinement variations have been studied. The results obtained enable the establishment of a variation of fracture properties depending on the level of confinement of each miniature specimen and selection of the most appropriate confinement for this goal. Graphical abstract Unlabelled Image Highlights • Influence of confinement levels in the fracture properties has been studied. • New pre-notched dog-bone-shaped specimens has been used. • Different confinement levels tested on P-SPT specimens. • Relationship between fracture toughness and confinement levels has been analysed. [ABSTRACT FROM AUTHOR]

To establish the tensile constitutive model of ultra-high performance concrete containing coarse aggregate (CA-UHPC), monotonic and cyclic uniaxial tensile tests for CA-UHPC with fiber volume fractions of 2.5% and 2.0% were conducted. Test results showed that CA-UHPC exhibits approximately linear stress-strain relation up to the tensile strength, and tensile softening response composed of the smeared- and localized-cracking stages, regardless of the tested fiber contents. Based on the monotonic test data, the tensile stress-crack opening model of CA-UHPC was established, and the model was further simplified into tri-linear relation. Based on the cyclic test results, tensile damage evolution laws according to the strain equivalence principle and the energy equivalence principle were developed, respectively. Finally, the proposed tensile constitutive model and the calibrated tensile damage evolution laws were demonstrated to effectively predict the mechanical response of CA-UHPC members under both monotonic tension and cyclic tension through numerical simulations. • Monotonic and cyclic uniaxial tensile tests for ultra-high performance concrete containing coarse aggregate (CA-UHPC). • Establishment of the tensile stress-crack opening model. • Quantification of fracture energy for smeared cracking and localized cracking. • Establishment and calibration of the tensile damage evolution law. • Numerical verification of the proposed tensile stress-crack opening model. [ABSTRACT FROM AUTHOR]