Properties of rubber pdf

To learn more, view our Privacy Policy. To browse Academia. Log in with Facebook Log in with Google. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Pongdhorn Saeoui. A short summary of this paper. Download Download PDF. Translate PDF. Although phase size of the dispersed NRP is relatively large, the tensile strength tends to increase gradually with increasing NRP content.

The phenomenon of strain-induced crystallization is proposed to explain the results. This is thought to be a consequence of thermal degradation of the NRP during the recycling process. All rights reserved. Introduction reusable scrap and easy recycling. TPO can be easily prepared at relatively low cost the functional performance of conventional elastomers. During the last four decades, the development of TPE has Preparation of TPV, on the other hand, requires a more gained much attention in the sector of polymer science and complicated process because the dispersed rubber phase technology.

Nowadays, TPE has become one of the polymer must be crosslinked during mixing, mostly through classes which have very high level of commercial impor- dynamic vulcanization or an in-situ crosslinking process. To tance. High heat resistance rubbers such as ethylene Pathumthani , Thailand. Sae-Oui et al. However, TPE prepared from natural rubber, so called Fig. Plot of complex viscosity versus angular frequency of the TPNRs.

To Ltd. All materials were used as received. Preparation of NRP a certain time, leading to high risk of thermal degradation. In this work, the process of TPNR preparation, without HA-latex was mixed with the other ingredients dynamic vulcanization, is proposed by blending HDPE with according to the formulation shown in Table 1.

After mix- pre-vulcanized natural rubber powder NRP. The pre-vulcanized latex was then fed into properties including recyclability were investigated.

The natural rubber powder NRP 2. Experimental obtained was subsequently dried at room temperature under vacuum for 3 h. Finally, morphology of the NRP was 2. Zinc oxide was supplied by Univenture PCL. Potassium hydroxide and ammonia solution were supplied by Bang 2. The tensile properties and tear strength were determined using a universal testing machine Instron series following ISO 37 die type 1 and ISO 34 die B , respectively.

The compression set was investigated according to ISO method B at room temperature for 22 h. The samples were cryogenically cracked in liquid nitrogen. The SEM micrographs were taken after the dried surfaces E. The mixing cooled down. The determined. Results and discussion the result recorded. Rheological behavior Plot of complex viscosity versus angular frequency of the TPNRs at various blend ratios is given in Fig.

Obvi- ously, the complex viscosity decreases with increasing angular frequency which is the characteristic of pseudo- plastic behaviour [14]. With increasing angular Fig. Stress—strain curves of the TPNRs.

At a given about a slight reduction in crystallinity of HDPE which angular frequency, G0 increases with increasing NRP should, consequently, result in impaired mechanical prop- content, i.

In addition to the strain- is proposed to explain the results. Mechanical properties However, further increase of the blend ratio has no signif- icant effect on the elongation at break.

Explanation is given by the combined effect of stress—strain curve of TPNR shows plastic-like behavior the reduction in crystallinity of HDPE and the dilution with relatively high initial modulus and low elongation at effect as neat NR generally possesses lower modulus than break. Since modulus is closely related to hardness, decreased as indicated by the reduced initial modulus and a similar trend is also observed for the hardness results and the increased elongation at break.

Interestingly, for TPNRs the same explanation applies. In all of the mechanical tests, the CRC specimens remained intact after failure did not shatter compared to a conventional concrete mix. Such behavior may be beneficial for a structure that requires good impact resistance properties. If no special considerations are made to maintain a higher strength values, the use of CRC mixes are recommended in places where high strength concrete is not required.

The intent was to use such mixes on urban development related projects. A list of feasible projects was identified. Examples are: roadways or road intersections, sidewalks, recreational courts and pathways, and wheel chair ramps for better skid resistance. This collaboration has also expanded to include members from industry associations, concrete suppliers and consultants. Finding a way to dispose of the rubber in concrete would enhance the understanding on how to incorporate the crumb rubber in greater engineering usage.

It is realized that partnership with states, industries and consultants is vital for the success of such initiative. Several crumb rubber in concrete test sections were built throughout the state of Arizona and are being monitored for performance. Laboratory tests were conducted at ASU and industry associations to support the knowledge learned in the field. This paper summarizes findings to date and knowledge learned in the field.

The huge stockpile of used tires in the United States US , which is estimated at about 2 to 3 billions, has been posing an environmental and health hazard to the public. How to reuse those stockpiled tires has been a driving force for new ideas, which has lead to a number of field experiments of using crumb rubber in Portland cement concrete.

Early studies by Eldin and Fedroff explored the effect of rubber chips on the compressive and flexural strength of CRC mixes 1,2. Schimizze et al. Biel and Lee experimented with a special cement Magnesium Oxychloride type for the purpose of enhancing the bonding strength between rubber particles and cement 4. They found that using rubber particles would improve the engineering characteristics of concrete.

Freeze-thaw durability of rubber concrete was investigated by Fedroff, Savas and Ahamd 6. Lee and Moon investigated adding crumb rubber into latex concrete 7. Khatib and Bayomy proposed a compressive strength reduction model of concrete mixes with added rubber content 8.

Thong-On reported on the mechanical behavior of crumb rubber cement mortar 9. Similar work on mechanical evaluation of rubber concrete has also been reported outside of the US. This included studies by Li et al. The major findings were that rubber concrete would suffer a reduction in compressive strength while it may increase ductility.

Whether rubber concrete is suitable for any practical application has remained to be explored. In February , a section of rubber concrete sidewalk was poured on the campus of ASU with a content of 40 lbs of crumb rubber per cubic yard of concrete.

A routine amount of sampling and testing was performed. Compressive strength on cored samples were as high as 3, psi. In June , a wheel chair ramp near a building on ASU campus was also poured with a design of 20 lbs of crumb rubber per cubic yard. In March , a resident in Mesa AZ, had the contractor pour his patio foundation with rubber concrete 20 lbs.

In March , the author experimented with the use of rubber concrete 25 lbs of crumb rubber per cubic yard for a sidewalk at his home in Scottsdale, Arizona. Three mixes had up to 60 lbs of crumb rubber per cubic yard, with no air- entraining agent AEA. The major purpose of this experiment was to evaluate the use of crumb rubber concrete as reducing the need for air entraining agents in cold climate. Again, an extensive sampling and testing program was conducted.

Perhaps the single largest project that utilized higher contents of crumb rubber in concrete was an experimental outdoor tennis court in Phoenix. Leading to the final construction of this tennis court, a series of experimental test slabs 2 x 4 ft in size, with a thickness of 2 to 3 inches were built in January with rubber content varying between 50 to lbs. The experimental testing program included: compressive strength, flexural strength, indirect tensile strength, and thermal coefficient of expansion.

The preliminary results were very encouraging. Thus, the crumb rubber concrete may exhibit good characteristics in controlling crack initiation and propagation. To further evaluate this hypothesis, in January , the first of several test slabs, 5 x 25 feet and 2 inches thick, was built. No shrinkage cracks have been observed to date. It should be noted that the slab serves as a truck parking facility. Encouraged by the performance of this first slab, additional slabs have been built and are being evaluated.

Kaloush, Way and Zhu 5 The building of these test slabs have provided very useful experience and the means to evaluate firsthand knowledge about mixing, hauling, pumping, placing, finishing, and curing of crumb rubber concrete. Laboratory evaluation tests included compressive strength, thermal coefficient of expansion, fracture, shrinkage cracking and microscopic matrix analysis. Through a series of the above-mentioned test sections, these possible advantages were evaluated and results are discussed in the following sections.

The first six were trial mixes of various amount of crumb rubber 0, 50, , , , and per cubic yard of concrete. It was a standard psi concrete with no air-entraining agent. The mixes with crumb rubber content of and lbs per Cyd were obtained from test slabs prepared for the tennis court experiment in Phoenix.

These mixes were a standard psi concrete and with no air- entraining agent. Figure 1 also shows the development of compressive strength, slump and air content of the trial mixes as a function or rubber content. The crumb rubber particles size were about 1 mm. Compression tests were conducted on cylindrical specimens 3 x 6 in under closed- loop control with measurements of axial and radial strains. Three point bending flexural tests were performed on 18 x 4 x 4 in beam specimens with an initial notch of 0.

A test span of 16 in was used. The deflection of the beam was also measured using a spring-loaded LVDT with a 0. The test was performed with the loading controlled by CMOD feedback. Development of these testing procedures has been discussed in an earlier work The indirect tensile strength was conducted on disc specimens approximately 1 inch thick and 4 inches in diameter. The load was applied at a constant rate of deformation of 0.

The test was stopped at total failure of the specimen. The horizontal tensile stress at the center of the test specimen was calculated. The indirect tensile strength is the maximum stress developed at the center of the specimen in the radial direction during loading for a fixed geometry. The time until failure and strains at failure were also recorded. Test Results Compressive Strength — Trials and Tennis Court Mixes Figure 1 showed the compressive strength, unit weight, slump and air content as a function of the rubber content.

The compressive strength decreased as the rubber content increased. The model coefficient of determination is 0. The unit weight decreased approximately 6. The slope was also notably decreased, and at crumb rubber content of lbs, the mix was so dry that additional water needed to be added to improve workability. Investigative efforts by Thornton Kelly of Hansen Aggregates, Phoenix, Arizona, determined that the entrapped air could be substantially reduced by adding a de-airing agent into the mixing truck just prior to the placement of the concrete.

Regrettably, much of Thornton Kelly work on mixing and placement of crumb rubber concrete did not continue as he passed away in early Compressive Strength — Pavement Sections Table 2 present additional closed loop compression tests conducted at 14 and 28 days for the tennis court mixes as constructed lbs CR per Cyd, and a trial mix of lbs CR per Cyd , in addition to the thin whitetopping PCC pavement sections a control and a 50 lbs CR per Cyd mixes.

First it is noted that the high rubber contents greatly reduces the compressive strength of the mixes; note that the closed loop compressive strength controlled by stress developed in the specimen yields lower compressive strength results compared to a conventional compressive strength test, however, for tennis court non-structural use the compressive strength are considered adequate.

The peak axial strain is 6 to 10 times higher than a control mix or a mix with low rubber content. The modulus of elasticity decreased slightly for the low crumb content mix, and was also drastically reduced for the high crumb rubber mixes almost equivalent to an asphalt concrete modulus.

Flexural Strength The flexure response in this test is dominated by the cracking that initiates at the notch and grows along the depth of the specimen.