Incorporation of rubber particles in portland cement concrete is an effective way of consuming waste rubber. This paper presents results of a study on the fatigue properties of plain concrete, rubberized concrete, and polypropylene fiber (PPF) reinforced rubberized concrete. Fatigue tests demonstrate that the inclusion of 60-kg rubber particles in 1 m3 concrete can greatly increase the fatigue life of concrete and that the addition of PPF to rubberized concrete can further enhance the fatigue life. The S-N equations for the three types of concrete are obtained by linear regression. Analyzing the acoustic emission (AE) signals recorded during the fatigue test reveals that both the activity and intensity of AE signals detected in rubberized concrete are much lower than in plain concrete. Good linear correlation between the hit and the minimum strain is observed for both concretes. Analyzing the distribution of energy during the cyclic loading shows that the fatigue process of concretes can be separated int...

Traditional construction techniques, such as in-situ casting and pre-cast concrete methods, have well-established testing protocols for assessing compressive strength and modulus of elasticity, including specific procedures for sample preparation and curing. In contrast, 3D concrete printing currently lacks standardized testing protocols, potentially contributing to the inconsistent results reported in previous studies. To address this issue, RILEM TC 304-ADC initiated a comprehensive interlaboratory study on the mechanical properties of 3D printed concrete. This study involves 30 laboratories worldwide, contributing 34 sets of data, with some laboratories testing more than one mix design. The compressive strength and modulus of elasticity were determined under three distinct conditions: Default, where each laboratory printed according to their standard procedure followed by water bath curing; Deviation 1, which involved creating a cold joint by increasing the time interval between printing layers; and Deviation 2, where the standard printing process was used, but the specimens were cured under conditions different from water bath. Some tests were conducted at two different scales based on specimen size—“mortar-scale” and “concrete-scale”—to investigate the size effect on compressive strength. Since the mix design remained identical for both scales, the only variable was the specimen size. This paper reports on the findings from the interlaboratory study, followed by a detailed investigation into the influencing parameters such as extraction location, cold joints, number of interlayers, and curing conditions on the mechanical properties of the printed concrete. As this study includes results from laboratories worldwide, its contribution to the development of relevant standardized testing protocols is critical.