Mechanical Behaviour of Completely Decomposed Granite Soil with Tire Rubber Granules and Fibres

Mixing soil with waste tire rubber granules or fibres is a practical and promising solution to the problem of global scrap tire pollution. Before successful applications, the mechanical behaviour of the soil–rubber mixture must be thoroughly investigated. Comprehensive laboratory studies (compaction, permeability, oedometer and triaxial tests) were conducted on the completely decomposed granite (CDG)–rubber mixtures, considering the effects of rubber type (rubber granules GR1 and rubber fibre FR2) and rubber content (0–30%). Results show that, for the CDG–rubber mixture, as the rubber content increases, the compaction curves become more rubber-like with less obvious optimum moisture content. The effect on permeability becomes clearer only when the rubber content is greater than 30%. The shape effect of rubber particles in compression is minimal. In triaxial shearing, the inclusion of rubber particles tends to reduce the stiffness of the mixtures. After adding GR1, the peak stress decreases with the increasing rubber content due to the participation of soft rubber particles in the force transmission, while the FR2 results in higher peak stress especially at higher rubber contents because of the reinforcement effect. For the CDG–GR1 mixture, the friction angle at the critical state (φ’cs) decreases with the increasing rubber content, mainly due to the lower inter-particle friction of the CDG–rubber interface compared to the pure CDG interface, while for the CDG–FR2 mixture, the φ’cs increases with the increasing rubber content, again mainly due to the reinforcement effect.

Mechanical Behavior of Sand Mixed with Rubber Aggregates

The main objective of this study is to compare the mechanical behavior of two sands (Hostun or Dune sands) mixed with crushed rubber obtained from used tires. However, it is essential to ensure that his geotechnical application do not result in long-term negative impacts on the environment. The chemical properties of these two sands are given by energy dispersive analysis X-ray fluorescence spectrometry. The mineral composition of these two sands is performed by X-ray diffractometry. The morphological characteristics of the sand grains are given by the analysis of the images of the two sands given by the scanning electron microscope. This study is based on 120 direct shear tests performed on sand-rubber aggregate mixtures. The results show that the rubber content of the aggregates has a significant effect on the shear strength of sand-rubber mixtures in both cases of sand. In fact, the shear strength of the sand-rubber mixture increases with increasing crushed rubber up to 20% for different normal stresses. The analysis of the test results also shows the effect of the angular shape of the sand grains on the interparticle friction. The contribution of the structure effect in the mobilized friction is analyzed by comparing the shear test results of Hostun and dune sand mixtures.

A method of designing equipment for heat processing of polymer workpieces

The paper describes a method of designing heating equipment that maintains a predetermined temperature field. The method consists in sequential solution of two problems. At the first stage, the heat generation field was calculated using the stationary heat conduction equation. At the second stage, parametric optimization of the temperature field was performed with reference to the power and configuration limits of the heaters. To test this method, the problem of maintaining a predetermined non-uniform temperature field was solved. A practical example of the application of the method for designing a uniform heating plate used in vulcanizing presses was given. To assess the efficiency of the plate, the results of modeling the heat processing of a workpiece from a rubber mixture were presented.

The Experimental Investigation of the Repeated-Loading Behaviour of the Sand-Rubber-Mixture (SRM)

Nowadays the waste rubber problems are concerned due to the environmental issues, storage, and recycling difficulty. However, the rubber base equipment has been widely used to protect structures for vibrations - that has been generated by the structure or induced from the vicinity area or the bedrock into the structure - due to the notable capability of absorbing energy. In this study, the repeated-loading behaviour of the Sand Rubber Mixture (SRM) has been investigated and the remarkable energy absorption properties of the mixture have been illustrated. The test soil material that has been used in this study was a well-graded sand (SW) with a mean grain size of 2 mm. The test martial rubber that has been used was grain particles with a uniform size of 4.76 mm. The sand rubber mixture (SRM) was prepared by using 7.5% rubber inclusion because it was found as the optimum rubber content. A series of force control repeated-loading CBR tests have been arranged. The effect of mixing rubber particles with the well-graded sand (SW test material) has been investigated. This shows the remarkable energy absorption capability of Sand Rubber Mixture (SRM) to protect the bed of a machine’s footing that is generating repeated loads. The SRM usage could be extended to be employed as a part of an energy absorption unit and dampers facilities beneath a machine footing or structures that are sensitive to the vibration to prevent destructive deformation and resonance phenomenon.

TECHNOLOGICAL ADDITIVES FOR OIL AND PETROL RESISTANCE RUBBERS BASED ON BUTADIENE-NITRILE CAOUTCHOUCS

The article investigated the influence of various technological additives (zincolet BB 222, lubstab-01 and MA-L22) on the technological properties of the rubber mixture, physical, mechanical and operational characteristics of rubber based on nitrile butadiene caoutchouc BNKS-40AMN. Basic rubber mixture studied included caoutchouc, BC-FF percadox, zinc monomethacrylate, maleide F, triallyl isocyanurate, acetonanil N, MGF-9 and THM-3 oligoester acrylates, carbon black P 514 and other ingredients. The rubber mixture was prepared on laboratory rolls LB 320 160/160 in two stages. At the first stage, BNKS-40AMN caoutchouc was mixed with ingredients and processing aids. As technological additives, zincolet BB 222, lubstab-01 and MA-L22 were used. In the second mixing step, BC-FF percadox and vulcanization coagents were introduced. For the obtained variants of the rubber mixture the vulcanization characteristics were studied on an MDR 3000 Basic rheometer at a temperature of 170 °C. The rubber mixture prepared was vulcanized in a P-V-100-3RT-2-PCD type vulcanizing press at 150 °C for 40 min. Determination of elastic-strength and operational properties of rubber were carried out according to the standards existing for the rubber industry. The oil resistance of the vulcanizates was evaluated by changing their elastic strength after exposure to standard liquid SZHR-1 at a temperature of 125 °C, as well as by changing the mass of the samples after exposure to a mixture of isooctane with toluene at room temperature. It was found that the introduction of technological additives in the rubber compound improves the distribution of carbon black P 514 and powdered ingredients (zinc monomethacrylate, maleide F, triallyl isocyanurate, acetonanil H) in the caoutchouc matrix. Increased elastic strength indicators and their smallest changes after exposure to aggressive hydrocarbon media is characterized a rubber containing technological additive MA-L22. A comparison of technological, elastic-strength properties and resistance to aggressive media for rubbers containing butadiene-nitrile caoutchoucs BNKS-18AMN, BNKS-28AMN and BNKS-40AMN with optimal technological additives for them was done. It has been established that rubber containing BNKS-40AMN and technological additive MA-L22 is characterized by improved vulcanization properties, increased elastic strength indicators and their smallest changes after exposure to aggressive hydrocarbon media.

Effect of feldspar filler on physical and dynamic properties of SBR/CB based tire tread compounds: Effect of addition method of silane coupling agent

In this work, the effects of using feldspar (FLD) as an alumina-silicate inorganic filler, with carbon black (CB) as a novel binary filler system, on the properties of SBR compounds were investigated for tire applications. The bis(triethoxysilylpropyl) disulfide (TESPD) was used for modification of FLD. The SBR hybrid composites were produced by replacing 10 phr of CB filler with neat FLD and functionalized FLD (F-FLD). The TESPD was added directly to the rubber mixture including neat FLD. The SBR composite which has only CB filler (50CB) was found to have the highest damping parameter (tan δ) value at 60°C. On the other hand, the composites loaded with the CB and the FLD fillers exhibited relatively lower tan δ at the same temperature showing lower rolling resistance meaning better fuel saving performance. The lowest rolling resistance was achieved for the 40CB-10F-FLD most probably due to its stronger interaction with the SBR elastomer molecules through the silane agent-assisted crosslinks of the F-FLD. As another dynamic property, the storage moduli at −20°C were found to be lower for the SBR hybrid composites as compared to that of the 50CB composite, exhibiting enhanced winter traction performance of the composites having FLD filler together with CB. The composites containing only 10 phr of FLD and F-FLD, on the other hand, exhibited very low tensile strength values which are not acceptable for tire tread materials.