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

Abstract

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.

Novel cement-based sandwich composites engineered with ground waste tire rubber: design, production, and preliminary results

“…RP and RG, with a nominal size gradation of 0e1 mm and 1e3 mm, respectively, were used as a total volumetric replacement of sand. These type of rubber fractions were already used in previous authors' research work, where detailed information on physical, chemical, granulometric, and morphological properties are available [8,23].…”

“…The acoustic insulation performance was evaluated experimentally by means of a custom-made impedance tube [8,27], following the test configuration illustrated in Fig. 6.…”

“…At the same sand-GWTR substitution level, the core mixes highlighted slightly different unit weight reduction rates (À46% and À41% for RP100 and RP50RG50, respectively). The use of only fine GWTR fraction in RP100 mix would imply a higher rubber content than the mix incorporating RG because of the higher packing degree (per unit of volume) in the cement paste of the finest fraction with respect to coarse one [8]. Further reason can be found in the different w/c ratios involved in the production of the two rubberized composites.…”

“…Technologically, the contribution to sustainable development comes together with specific effects on the engineering performances of concrete. Past and recent studies demonstrated that certain kinds of waste materials (demolished concrete, glass, plastics, wood, tire) can be successfully substitute a reasonable percentage of natural aggregates, conferring attractive engineering peculiarities, such as lightweight, higher dynamic mechanical properties, better thermal resistance, and improved acoustic performance [8].…”

“…Li et al [12] stated the feasibility to address concrete incorporating tire rubber particles in highway field as sound barriers and in building as an earthquake shock-wave absorber material for reinforced concrete column. Besides, rubberconcrete technology has been also proposed for the manufacturing of precast components and light architectural units, including sidewalk and wall panels [13], bricks for thermal energy-saving and control of noise pollution in residential and commercial buildings [14], and paving blocks [8]. Recently, in Europe, the role of GWTR for concrete was further consolidated by the issue of End of Waste decree [15], which, with the aim of promoting clean disposal methods for end-of-life tires, officially proposes the construction materials industry as a possible application sector for recycled tire rubber.…”