During the last years, several researches have been studying the final disposal of tyres wastes, due to the great volume generated worldwide, as well as the difficulty for discarding the disposal sites which become a serious environmental problem. In spite of this, recycling appears as the best solution for disposing tyres residues, due to its economical and ecological advantages. This research carried out to assess the feasibility of using crumb rubber (the product of shredding used rubber tyres) as a partial sand replacement in foamed concrete, and investigates the effect of it on some properties of foamed concrete such as, density, water absorption, compressive strength, tensile strength, flexural strength and impact resistance. Crumb rubber of tyres ranging from (0.7 to 5mm) in size was used in this research. Three proportioned mixes were designed in this research, have the same cement content, water-cement ratio, and foam content. The first mix represents a typical reference formulation of foamed concrete without crumb rubber (FC). In the others mixes (FCR-1 and FCR-2), respectively, 20 and 30% of volume of sand were replaced by crumb tyres rubber waste. Tests carried out to assess the behaviour of final product. The results obtained were demonstrated decreasing in foamed concrete strength (compressive, tensile, flexural, and impact) with the increasing of crumb tyres rubber content in the mixture and rubberized foamed concrete specimens (FCR-1 and FCR-2) show a cohesive behaviour than the specimens of reference mix (FC), especially in tensile strength. Comparing with the reference mix (FC), at an age of (28 days), the decreasing of compressive strength was (20.85%) for (FCR-1) and it for (FCR-2) was (37.76%).
In recent years, the elastomer forming technique has found acceptance on the shop floor and is used increasingly as a pressure- transmitting medium for various metal-forming operations. This is due mainly to the introduction of a new range of materials and of new concepts in tooling, which have served to kindle industrial interest in the process. The purpose of this paper is to study the sheet formability with compressible die (natural rubber). The forming was occurred using hemi-spherical punch and rubber die. Experimental tests were used to know the mechanical properties for rubber and sheet materials which were brass and aluminum. After that several forming processes were prepared with a 58 mm diameter steel ball as a punch to form 0.5 thickness brass and aluminum dishes with different diameters (15-40 mm). Force-stroke history was plotted through forming to find the stiffness of formed plate with rubber die and later to compare this parameter for different diameters. Wrinkling and springback were pointed for the formed dishes. It was found that the stiffness of the formed dish increases with diameter until reaching to the diameter at which wrinkling will takes place (about 33 mm for aluminum and 28mm for brass), and then the stiffness will decreases with diameter above this value. It was found that the springback ratio (ratio of final high to the stroke) was increased with diameter until wrinkling takes place, and this ratio is greater for aluminum than that for brass. The results show that it is able to use natural rubber as a die for sheet metal forming with limitation of using small sheet thickness
This study is the second stage of the paper “Studying the Effect of Rubber- Silicone on Physical Properties of Asphalt Cement”. The present study examines the effect of additives on asphalt mixture performance. Asphalt mixture has been designed by Marshall Method for determining the optimum asphalt content and geophysical properties of mix according to ASTM (D-1559). Rubber-silicone at different percentages (1%, 2%, 3% and 5%) was added to asphalt binder. Six specimens of asphalt rubber silicone mixture (ARSM) for each percentage are prepared and evaluated according to Marshall method. Diametric tensile creep test ASTM (D-1075) at 60 Co was used to evaluate permanent deformation and modulus of elasticity for ARSM. The study showed that the Rubber-Silicone has more effects on performance of asphalt mixture by increasing the Marshal stability, air voids, and reducing the flow and bulk density compared with the original mix. It also increases the flexibility properties of the mix and this appears from reducing the permanent deformation at test temperature (60C), the reduction percent is about (30 to 70) %.
Concrete structures suffer from the impact of many harmful attacking materials that affect theproperties of the main material in them, which is concrete. These structures are also, exposedto the negative impact of many hostile environments such as soils containing harmful salts andharmful acids. A number of precautions should be considered in order to protect the concreteused in such structures. Adding polymer to concrete components as a percentages weight ofcement is one of the methods for producing polymer-modified concrete, which has lowpermeability, better mechanical properties and is more resistant to the negative effects ofharmful environmental factors. The utilization of polymers could help in protecting structuresand enhancing concrete strength. In this study, concrete mixes were prepared with inclusion ofstyrene butadiene rubber (SBR) polymer at four percentages (0%, 5%, 7% and 10% by cementweight). Co-polymers of butidine with styrene (styrene-butadine rubber (SBR)), are a group oflarge-volume synthetic rubbers. High adhesion occurs between the polymer films that formand cement hydrates. This action gives improves the properties of concrete such as flexuraland compressive strength and gives also a higher durability. The investigation was extended toevaluate the compressive strength of the SBR concrete mixes immersed in three types ofwaters: tap, drainage and ground water, at three different ages. The results showed that SBRpolymer enhanced the compressive strength of concrete significantly. A comparison betweenreduction in strength of concretes immersed in these three types of waters was also presented.Moreover, the presence of SBR polymer led to reduced loss in strength of concrete specimensimmersed in drainage and ground water. A proposed model to determine the compressivestrength of concrete specimens immersed in drainage and ground waters was deduced. Thismodel could be a helpful tool for rapid and easy estimation of the strength of concretespecimens immersed in drainage and ground water at different contents of SBR polymer. Theresults showed the highest improve in compressive strength to be associated with 7% SBRmixes at the three tested ages. The increases in this strength at days 7, 28 and 56 with inclusionof 7% SBR polymer were 112.8%, 113.9% and 116%, respectively, compared to OPC mix.
This research work includes production of polymer modified polystyrene concrete and studies the mechanical properties. Several proportions of raw materials were used to produce this type of concrete. This study is intended to improve the mechanical properties of light weight polystyrene concrete using styrene butadiene rubber(SBR) with rate of (5,10,15and20)% of cement weight. Compressive strength, flexural strength, impact strength and dry density tests were made on more than 150 specimen at age of 28 days. The results show that the addition of (SBR) with range of (5-20)%of cement weight is improve the flexural strength with range (3.74-18)%, and improve the impact strength with range (39-163)%. Also the results show that it is possible to produce polystyrene concrete with density (1680,1433 and 1147) kg/m3 replacing light weight Polystyrene aggregate with volume fraction (30,50 and70)%of sand.
The presented work investigates the effect of addition admixtures (superplasticizer and polymer) to Chopped Worn-Out Tire concrete as a partial replacement of cement weight. Superpasticizer was addition by 4% and polymer (SBR) by 15%. The Chopped Worn-Out Tire (Ch.W.T.) addition to reference concrete with the three proportions as a Partial Replacement Ratio (PRR) of (25,25),(20,30),and (30,20) by volume of (sand and gravel) respectively. Three mixes were selected with above PRR for each type of admixture in additional to three mixes for Ch.W.T. concrete without admixtures and three reference mixes with admixtures without Ch.W.T. Thus, twelve mixes could be used in this investigation. Compressive strength and modulus of elasticity (static and dynamic) were tested. The test results indicated that the use of admixture led to significant improvement in concrete properties in general. Superplasticizer gave best results comparative with polymer, for example at 28 day the compressive strength of superplasticizer Ch.W.T. concrete Csp25,25 was 32.5 MPa, while compressive strength of polymer modified Ch.W.T. concrete CB25,25 was 28 MPa and compressive strength of Ch.W.T. concrete C25,25 was 21.2 MPa.
This research investigates the impact resistace of reinforced high strength concrete slabs with steel meshes (BRC) modified by styrene butadiene rubber (SBR) with different weight ratios of polymer to cement as follows: 3%, 5% and 7%. Reference mix was produced for comparison of results. For all selected mixes, cubes (100×100×100mm) were made for compressive strength test at (365) days. In conducting low-velocity impact test, method of repeated falling mass was used: 1400gm steel ball falling freely from height of 2400mm on reinforced panels of (50×50×800 mm) reinforced with one layer of (BRC). The number of blows causing first crack and final perforation (failure) were calculated, according to the former results, the energy of each case was found. Results showed an improvement in compressive strength of polymer modified high strength concrete (PMHSC) over reference mix; the maximum increase being of it were (3.93%-11.96%) at age of (365) days. There is significant improvement in low-velocity impact resistance of all polymer modified mixes over reference mix. Results illustrated that polymer modified mix of (3%) give the its higher impact resistance than others, the increase of its impact resistance at failure over reference mix was (154.76%) while, for polymer modified mix (5%) it was (30.95%) and it was (14.28%) for polymer modified mix of (7%).