Ground Waste Tire Rubber as a Total Replacement of Natural Aggregates in Concrete Mixes: Application for Lightweight Paving Blocks

The use of waste materials as alternative aggregates in cementitious mixtures is one of the most investigated practices to enhance eco-sustainability in the civil and construction sectors. For specific applications, these secondary raw materials can ensure adequate technological performance, minimizing the exploitation of natural resources and encouraging the circular disposal of industrial or municipal waste. Aiming to design and develop lightweight paving blocks for pedestrian or very light-traffic purposes (parking area, garage, sidewalk, or sports surfaces), this paper presents the material characterization of rubberized cement mortars using ground waste tire rubber (0–1 mm rubber powder and 1–3 mm rubber granules) to totally replace the mineral aggregates. Considering recommended requirements for concrete paving members in terms of mechanical strength, water drainage performance, acoustic attenuation, and dynamic and energy absorption behavior, a comprehensive laboratory testing is proposed for five different formulations varying the sand-rubber replacement level and the proportion ratio between the two rubber fractions. Tests highlighted positive and promising results to convert laboratory samples into pre-cast members. The “hot” finding of the work was to prove the feasibility of obtaining totally rubberized mortars (0 v/v% of sand) with suitable engineering performance and enhanced eco-friendly features.

A Comparative Study between the Usages of Differently Sized Waste Rubber Obtained From Tires over the Strength Performance of Rigid Road Pavements

In this research work, waste rubber obtained from tires is mainly used as a fractional substitution of natural coarse aggregate to improve the strength aspects of the concrete. 3 dissimilar sizes of waste rubber obtained from tires aggregates were used that is of 4mm, 10 mm and 16 mm. Depending upon all three sizes all the waste rubber obtained from tires aggregate were used at 3 different percentages that are at 10 percent, 20 percent and 30 percent. Then several concrete samples were prepared depending upon the shape and percentage of the waste rubber obtained from tires aggregate. Then all these samples were cured and tested after 7 days and 28 days. Depending upon the results obtained after these above-discussed test various conclusions has been drawn which are as follows. It was found that the maximum strength was obtained at 20 percent usage of 4mm sized waste rubber obtained from tires aggregate, the strength obtained at 20 percentage with 4mm size was maximum as compared to all other concrete samples, so it can be concluded that the compressive strength depends upon both the size as well as on the percentage of waste rubber obtained from tires aggregate and with the decrease in size of the waste rubber obtained from tires aggregate the strength was increasing. From the test results of the split tensile strength test and flexural strength test, it was found that the maximum strength was obtained at 20 percent usage of 4mm sized waste rubber obtained from tires aggregate and with the increase in size and percentage the strength was declining. So therefore it can be concluded that both split tensile strength and flexural strength depends upon the size of waste rubber obtained from tires aggregate and the percentage of waste rubber obtained from tires aggregate. From the obtained test results it can be concluded that with the addition of the waste tire rubber the overall internal micro-structure of the concrete improves which further leads to enhanced mechanical strength of the concrete. This was due to the physical properties and the chemical composition of the waste tire rubber particles which fills the internal pores in a broader way and lead to improved mechanical strength.

Thermochemical compatibilization of reclaimed tire rubber/ poly(ethylene-co-vinyl acetate) blend using electron beam irradiation and amine-based chemical

Waste tire rubber is commonly recycled by blending with other polymers. However, the mechanical properties of these blends were poor due to lack of adhesion between the matrix and the waste tire rubber. In this research, the use of electron beam irradiation and (3-Aminopropyl)triethoxy silane (APTES) on enhancing the performance of 50 wt% reclaimed tire rubber (RTR) blend with 50 wt% poly(ethylene-co-vinyl acetate) (EVA) was investigated. Preparation of RTR/EVA blends were carried out in the internal mixer. The blends were then exposed to electron beam (EB) irradiation at doses ranging from 50 to 200 kGy. APTES loading was varied between 1 to 10 wt%. The processing, morphological, mechanical, and calorimetric properties of the blends were investigated. The stabilization torque and total mixing energy was higher in compatibilized blends. Mechanical properties of RTR/EVA blends were improved due to efficiency of APTES in further reclaiming the RTR and compatibilizing the blends. APTES improved the dispersion of embedded smaller RTR particles in EVA matrix and crosslinking efficiency of the blends. Calorimetric studies showed increased crystallinity in compatibilized blends which corresponds to improved mechanical properties. However, the ductility of the blend was decreased due to increased interaction between EVA and APTES. Presence of APTES increased the efficiency of electron beam irradiation induced crosslinking which was shown through gel content analysis and Charlesby-Pinner equation.