The use of rubberized concrete has become increasingly popular as a means of disposing of waste materials, such as used and end-of-life tires, while also providing an effective solution for construction applications. The strength and durability of rubberized concrete can be negatively affected by temperature fluctuations, but little is known about the performance of this material. Hence, the work presented herein aims to evaluate the performance of rubberized concrete when it is exposed to different temperature levels. In this study, rubberized concrete specimens were prepared by replacing 5–20% of crumb rubber by volume of fine aggregate. The specimens underwent a curing process for 28 days, followed by exposure to temperatures of 200 °C, 400 °C, and 600 °C for a period of 2 h. The residual test and normal cooling method were adapted. Surface characteristics by visual inspection, the residual weight, compressive strength, splitting tensile strength, ultrasonic pulse velocity, and dynamic modulus of elasticity were assessed and compared to unheated specimens. The study’s findings revealed that, when exposed to temperatures between 200 °C and 400 °C, rubberized concrete containing a 5% to 15% rubber content experienced less reduction in compressive strength than conventional concrete, which showed a reduction of 43% to 48.5%. Also, it was observed that the splitting tensile strength was more sensitive to elevated temperatures than the compressive strength.

Most metropolitan areas in the world are facing major solid-waste-disposal problems. The solid-waste problem is considered one of the major environmental problems that countries and environmental organizations are paying increasing attention to at present, not only due to its negative effects on public health and the environment, but also due to the dangers it may cause to the nearby residential communities. One of the visible solutions is to reuse solid waste as a partial replacement of concrete constituents. In this investigation, fine aggregate was replaced with crumb rubber at four different volumetric percentages, ranging from 5 to 20% with a 5% step size. A novel treatment technique based on a combination of chemical and thermal treatments of a crumb rubber surface was adopted. A superplasticizer was added to improve both the workability and the strength of the concrete mixtures. The mixtures were assessed in fresh and hardened phases and compared with a control mix. In the fresh phase, the mixtures were evaluated regarding workability and wet density; and in the hardened phase, compressive strength after 180 days, tensile and flexural strength after 90 days, dry density, and absorption were investigated. Additionally, the mixes were assessed using non-destructive tests, namely, the ultrasonic pulse velocity test, rebound hammer test, and core test. The results showed that the addition of rubber particles to concrete decreased the compressive strength, tensile strength, and flexural strength in comparison with control concrete. An empirical equation based on combined analysis with R² = 0.95 was derived. At the age of 180 days, the compressive strength of rubberized concrete varied from 34 to 42 MPa. From a structural point of view, its strength is regarded as acceptable.

The paper presents in detail a method of calculating the forces acting on a 1T6R robot manipulator. To determine the reactions (forces in kinematic torques), you must first determine the inertial forces in the mechanism to which one or more payloads of the robot can be added. The torsion of the inertial forces is calculated using the masses of the machine elements and the accelerations at the centers of mass of the elements of the mechanism, so that the positions, speeds, and accelerations acting on it, ie its complete kinematics, will be determined. Equations of the dynamics are also determined through an original method.