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Use of waste rubber as concrete additive
Abstract
For resource reutilization, scrap tyres have long been investigated as an additive to concrete to form 'Rubcrete' for various applications and have shown promising results. However, the addition of rubber particles leads to the degradation of physical properties, particularly, the compressive strength of the concrete. In this study, a theoretical model was proposed to shed light on the mechanisms of decrease in compressive strength due to the addition of rubber particles as well as improvement in compressive strength through modification of particle surfaces. The literature suggests that the compressive strength can be improved by soaking the rubber particles in alkaline solution first to increase the inter-phase bonding between the rubber particles and cement. Instead, we discovered that the loss in compressive strength was due to local imperfections in the hydration of cement, induced by the addition of heterogeneous and hydrophobic rubber particles. Microscopic studies showed that the rubber particles disturbed the water transfer to create channels, which were prone to cracking and led to a loss in the compressive strength. Unexpectedly, no cracking was found along the surfaces of the rubber particles, indicating that the bonding strength between the rubber particles and cement phases was not the critical factor in determining the compressive strength. Therefore, a theoretical model was proposed to describe the water transfer in the Rubcrete specimens to explain the experimental data. In the model, the local water available for hydration (Q) is: Q = -A(slv)/6piv, where Q, A(slv), and v are mass flow rate (kg s(-1)), Hamaker constant (J), and dynamic viscosity (m2 s(-1)), respectively. By maximizing the quantity Q and, in turn, the Hamaker constant A(slv), the compressive strength could be improved. The Hamaker constant A(slv) for water film on rubber particle surfaces was smaller than that for the hydrated cement particles; the water transfer rate was lower in the presence of rubber particles because the Hamaker constant A(slv) for water film on rubber particle surfaces was smaller than that on the hydrated cement particles. Thus, the compressive strength of Rubcrete could be improved by increasing the Hamaker constant of the system. This was achieved by increasing the refractive indices of the solids (n(s)). The refractive indices of materials increase with increases in functional groups, such as OH and SH on the surface. The model provided a possible mechanism for the efficacy of treating rubber particles with NaOH in improving the compressive strength. By using NaOH solution treatment, an oxygen-containing OH group was formed on the rubber surface to increase the Hamaker constant of the system, leading to higher compressive strength. Based on this mechanism, a novel method for modification of the rubber particles was also proposed. In this process, the rubber particles were partially oxidized with hot air/steam in a fluidized bed reactor to produce the hydrophilic groups on the surface of the particles. Preliminary results obtained so far are promising in accordance with the theory.
... Findings (Eldin and Senouci 1993;Eldin and Senouci 1994;Topçu 1995) confirmed that replacing coarse aggregate by coarse rubber particles significantly decrease the compressive ( Figure 2) and tensile strength ( Figure 3) of concrete in compression with replacing sand by fine rubber. This reduction is attributed to (1) replacing higher strength and load-carrying capacity aggregate by lower one (Xue and Shinozuka, 2013) (2) the weaker bond between rubber aggregates and cement past which lead to rapid rupture of concrete (Bisht and Ramana 2017) (3) disturbing the water transfer process which lead to imperfections in the hydration of cement surrounding rubber particles and overall dropping in compressive strength capacity of concrete (Chou et al., 2007). (Eldin and Senouci, 1992). ...
... Rubberized Concrete Properties-Improvement Techniques Many methods for improving the engineering characteristics of RBC have been introduced to the literature including rubber pre-treatment with NaOH solution (Raghavan et al., 1998;Segre et al., 2002;Albano et al., 2005;Chou et al., 2007;Tian et al., 2011;Youssf et al., 2014;, addition of silica fume and steel fiber (Youssf et al., 2014;Noaman et al., 2015;Wang et al., 2018), and limestone powder pre-coating (Onuaguluchi and Panesar, 2014). ...
... They reported a presence of zinc stearate on the rubber's surface and indicated that this compound would be removed from the surface by NaOH treatment, which will cause a considerable change in the treated rubber leading to an enhanced adhesion in-between the recycled material and the cement paste. Chou et al (Chou et al., 2007) reported that modifying the surfaces of rubber by 10% NaOH solution decreases its negative effect on the hydration process by means of disturbing the water transfer which helps in recovering the reduction in the concrete strength. Youssf et al (Youssf et al., 2014) concluded that treating rubber by 10% NaOH solution enhances concrete compressive strength by 6% and 15% at 7 and 28 days, respectively, in comparison to non-treated one. ...
In recent years, extensive research has focused on investigating rubberized concrete as a structural material due to its enhanced properties, including increased ductility, improved energy dissipation, and higher damping ratios. Additionally, rubberized concrete contributes to sustainable development by recycling nonbiodegradable waste and reducing the use of natural aggregates in concrete mixtures. However, its performance in retrofitting existing structures remains unclear and requires thorough investigation before it can be widely implemented in construction activities. The main objective of this research is to evaluate the seismic performance of reinforced concrete buildings strengthened with rubberized concrete jackets under severe earthquake excitations. To achieve this, laboratory tests were conducted to assess the properties of highperformance, self-compacting rubberized concrete mixes with various rubber content levels. Additionally, finite element models of reinforced concrete retrofitted with these mixes were analyzed using nonlinear response history analysis to compare their performance against control models. The results of this experimental work indicate a significant reduction in the mechanical properties of rubberized concrete. However, there is a considerable improvement in the damping ratio, which enhances the energy dissipation capacity of the structures. This improvement contributes to an increase in damping energy and a reduction in hysteretic energy, suggesting that rubberized concrete jackets can enhance the seismic resilience of reinforced concrete buildings.
... As the amount of waste tyres is increasing year by year, efficient solutions for recycling this solid waste are important from both an environmental and a social point of view. A number of researchers have proposed a feasible method to shred tyres into smaller or larger crumbs for reuse in the concrete industry [10][11][12]. ...
The increasing population and expanding industrialization have given rise to an urgent demand to explore sustainable practices to use waste materials as valuable resources. Working on this approach, researchers have investigated diverse types of waste materials to be used in the concrete manufacturing industry. Waste scrap tyre is a category of waste that is produced in huge quantities and their efficient disposal is a challenge. Tyre burning, which is a popular method of managing tyre waste, produces harmful smoke and poses a fire risk as well. As a result, there is a dire need to work on the applications where recycled tyre materials can be used. In concrete, the use of scrap tyre rubber as a substitute for traditional aggregates is feasible. For this, the scrap tyre rubber is pre-treated to enhance mechanical properties and bond formation. In this chapter, the use of scrap rubber/crumb rubber as a fine or coarse aggregate or as a component of concrete, bricks, and road construction has been thoroughly investigated. The strength behavior of the concrete containing waste materials in comparison to the regular concrete has also been analyzed. Though, the rubberized concrete exhibited lower compressive strength than the regular composition; the rubber pre-treatment using sodium hydroxide (NaOH) solution and silica fume compensates for the loss and provides excellent strength and resistance to sulfate, acid, and chloride conditions.
Rubberized concrete effectively prevents brittle failures and enhances the ductility and energy absorption of concrete. It has been observed that the inclusion of rubber reduces the strength and abrasion resistance of concrete; however, the enhancement in energy absorption is significant. A vast number of tires end up as waste, posing a major environmental issue globally. The disposal of waste tires has become an acute environmental challenge, with billions discarded and buried worldwide, representing a significant ecological threat. Consequently, utilizing rubber in the concrete industry can be advantageous for both the environment and the industry. This study presents an extensive review of the effects of various rubber contents on the mechanical properties of concrete. The scope of the review encompasses an analysis of a diverse range of studies conducted over the past decade, focusing on the influence of rubber content on concrete's mechanical performance. The analysis revealed that the optimal amount of rubber to be used in concrete is in the range of 2–5% as a replacement for natural concrete aggregate. Furthermore, replacing aggregate with treated rubber may offer additional benefits, including improved energy absorption and sustainability. However, despite the promising benefits of rubberized concrete, there is a notable gap in the literature regarding the creep behavior of rubberized concrete, a crucial parameter for defining concrete performance, particularly in superstructures. This gap underscores the need for further research to comprehensively understand the long-term behavior of rubberized concrete under sustained loading conditions. Additionally, while coating or treating rubber could mitigate the reduction in mechanical properties associated with rubber inclusion, there remains a need for more investigation into the brittleness index and energy absorption of treated rubber. Addressing these gaps in knowledge will contribute to a more thorough understanding of the potential applications and limitations of rubberized concrete in various engineering contexts.
The aim of this work is to develop a model for the quantitative prediction of contact angles of variable liquids on cement-based systems. In this model, parameters such as relative humidity, roughness and porosity are considered in combination for the first time. Methodologically, an analytical model is derived based on classical theories of interface and wetting research such as the van Oss–Chaudhury–Good theory (vOCG), the Wenzel model and the Cassie model. This is followed by an experimental program on exemplary cement paste samples (CEM I, w/c = 0.40 and 0.50) in order to verify basic model parameters with empirical input values. The program includes contact angle measurements (CAM) on hardened cement paste at variable relative humidities, as well as atomic force microscopy (AFM) and mercury pressure porosimetry (MIP). Finally, the model is discussed with regard to certain parameters and validated using contact angle measurements on practical mortars and concretes.
Millions of used or worn-out tyres are disposed of by many countries annually. These tyres can be put to good use when recycled. Used tyres are among the most problematic and challenging sources of solid waste, especially in landfills. Therefore, the use of waste tyres for composite materials having desired performance properties can be used as a means of disposing of the tyres. Fibrous material-reinforced composites with enhanced physical and mechanical performance and incorporating sisal fibres were produced using waste tyre material, sisal, and polyester resin. The physical and mechanical properties of hybrid composite board panels, including flexural strength, compression strength, tensile strength, and water absorption, were determined according to ASTM Standards. The rubber tyre particles used in the study had a size of 1.00 mm, and the sisal used had an average length of 6mm. A systematic experimental design was formulated and worked accordingly in the fabrication of the composite. The hybrid composite produced has adequate mechanical properties to perform as a substitute for solid wood in several applications such as tabletops, general purpose, load-bearing boards, ceiling boards, furniture, door panels and partitioning boards.
One of the major environmental challenges facing municipalities around the world is the disposal of worn out automobile tires. To address this global problem, several studies have been conducted to examine various applications of recycled tire rubber (fine crumb rubber and coarse tire chips). Examples include the reuse of ground tire rubber in a variety of rubber and plastic products, thermal incineration of waste tires for the production of electricity or as fuel for cement kilns, and use of recycled rubber chips in asphalt concrete. Unfortunately, generation of waste tires far exceeds these uses. This paper emphasizes another technically and economically attractive option, which is the use of recycled tire rubber in portland cement concrete. Preliminary studies show that workable rubberized portland cement concrete (rubcrete) mixtures can be made provided that appropriate percentages of tire rubber are used in such mixtures. Achievements in this area are examined in this paper, with special focus on engineering properties of rubcrete mixtures. These include: workability, compressive strength, splittensile strength, flexural strength, elastic modulus. Poisson's ratio, toughness, impact resistance, sound and heat insulation, and freezing and thawing resistance. The benefits of using magnesium oxychloride cement as a binder for rubberized concrete mixtures are discussed. Various applications in which rubcrete could be advantageous over conventional concrete are described.
The main driving force for flow in very thin films can be the gradient in the van der Waals force. This phenomenon was used by Wayner et al. (1976) to develop an equation for the interline heat transfer coefficient of an evaporating wetting film. Buried in this development is a dimensionless group that can enhance, when properly viewed, the understanding of the evaporation process in the contact line region where the film thickness becomes vanishingly thin. This process is crucial in systems that rely on heat transfer in ultrathin films such as evaporating drops on solid surfaces and evaporating menisci in heat pipes. Herein, the authors discuss the significance and use of this dimensionless contact line heat sink number.
Accumulations of wom-out automobile tires create fire and health hazards. As a possible solution to the problem of scrap-tire disposal, an experimental study was conducted to examine the potential of using tire chips and crumb rubber as aggregate in portland-cement concrete. This paper examines strength and toughness properties of concrete in which different amounts of rubber-tire particles of several sizes were used as aggregate. The concrete mixtures exhibited lower compressive and splitting-tensile strength than did normal concrete. However, these mixtures did not demonstrate brittle failure, but rather a ductile, plastic failure, and had the ability to absorb a large amount of plastic energy under compressive and tensile loads. A mathematical model is used to describe the effects of rubber aggregate on the compressive and tensile strength reduction of concrete.
Growing piles of discarded tires create fire and health hazards. Current disposal methods are wasteful and costly. This paper presents the results of an investigation into the potential of shredded tires as fill material in road construction. A test road was built to study the constructability. durability, and performance of tire chips as a new construction material. The road was made up of six sections to examine the effects of (1) Tire-chip size; (2) method of placement; and (3) soil-cap thickness on road performance. The field operation proved that use of shredded tires in road construction poses no major handling or placement problems. However, the high compressibility of tire chips and their tendency to shift laterally under compaction equipment need to be noted. The performance of the test road was monitored under freeze-thaw conditions and under service loads. The road showed acceptable performance with moderate maintenance requirements and minimum undesirable effects on ground water quality under the tested conditions.
The properties of concrete incorporating scrap rubber tyre particles were investigated. Properties studied included the compressive, flexural properties as well as the vibration isolation capability. The rubber particles were either plain particles or pre-processed using one of two coating methods (coating with cement paste and coating with METHOCEL cellulose ethers solution) before mixing in concrete. The concrete mixtures incorporating rubber tyre particles exhibited lower compressive and flexural strength than normal concrete. However, the mixtures demonstrated a ductile failure, and had the capability of absorbing a large amount of energy under compressive and flexural loads. Moreover, they demonstrated excellent vibration isolation capability. These results indicate that the mixtures might be suitable for applications such as driveways, sidewalks or road constructions where strength is not a high priority but greater toughness is preferred, and where vibration reduction is required (e.g. base isolated structures and machine foundations).
Utilization of industrial waste products in concrete has attracted attention both with the energy crisis in the 70s and the rise of environmental consciousness. Most of the concrete properties can be improved by incorporating different kinds of industrial wastes. In this study, the changes of the properties for the rubberized concretes were investigated in terms of both size and amount of the rubber chips. The concretes are postulated to be a potential material especially for construction applications which are subjected to impact effects such as crash barriers, bridges and roads. With the cylindrical and cubic specimens produced by adding rubbers of volume ratios of 15, 30 and 45% into C 20 quality concrete, the physical and mechanical tests were conducted at the end of 7, 28-day and 6-month, and σ-ɛ diagrams were drawn. From the diagrams the toughness values and plastic and elastic energy capacities of these rubberized concretes were determined. It was observed that plastic energy capacities began to increase when the high elastic energy capacity of normal concrete was reduced by adding rubber. Due to their high plastic energy capacities these concretes showed high strains especially under impact effects.
Many properties of concrete can be changed by adding industrial waste materials in it. In this study, the effect of different amount of rubber chips on the brittleness of rubberized concretes were investigated. These kinds of concretes are used especially in structures which are exposed to crashing effects. The laboratory tests were conducted by using 15, 30 and 45% by weight two different sized coarse aggregate. On the prepared cylindrical specimens loading, unloading and reloading tests were carried out for 7 and 28-day, and σ-ε hysteresis loops were also drawn. Then the brittleness index values of these series were determined. The variation of brittleness index values were evaluated for different amount of rubber chips, compressive strength and toughness values. Finally, it was observed that concretes which contain 15% rubber chips gave the highest brittleness index values with low compressive strength and toughness values.
Rubberized concrete is recommended for highway barriers. It was observed that rubberized concrete's acquired competency to absorb energy resulted in a decrease in damages and injuries during the collision of vehicles with barriers. In this study, normal concrete was combined with two different sizes of rubber aggregate in order to examine the behaviours of rubberized concretes under collision impact. This was done through the comparison of experimental results. The collision impacts were researched as a dynamic problem, and the static results pertaining to cylindrical samples were converted into dynamic values. The values obtained were compared with values for both normal concrete and steel. The results showed that the impact resistance of rubberized concrete was higher, and it was particularly evident in concrete samples aggregated with thick rubber.
DLVO theory has been applied to cement suspensions containing admixtures. Two different batches of the same cement, different only in storage history, are compared. It is found that, although their general sedimentation behavior is similar, differences exist in the zeta potential and basic chemistry. Both the superplasticizer and water-reducing admixture result in all cases in a stable dispersion, contrary to the theoretical prediction that only a coagulated suspension should exist. This finding suggests that steric hindrance plays a larger role compared to electric repulsion in the deflocculation of cement pastes than previously believed. Zeta potential and sedimentation data for CaCl2 and sugar are also presented.