Mechanical Tests

Tensile strength and flexural strength were investigated for different sand contents to determine their impacts as a reinforcement material on the mechanical properties of plastic rejects.

Tensile Strength Test To determine the properties of tensile strength of the specimens, tests were done in accordance with ASTM D3039-00.57 Tensile strength test was performed in order to determine the ultimate tensile strength. Specimens were machined to dimensions of 25 by 250 by 2.5 mm in accordance with ASTM D3039-00. Gauge length was 100 mm, with the grips firmly holding the tabs. The tensile test occurs on a universal testing machine (UTS). Standard ribbed grips were used to hold the specimen in place. A constant head speed of 5mm/min was used to allow for failure anywhere between 1 and 10 minutes.

The tensile properties for the different reinforcing elements showed great significance in the way the material behaves, as shown in Figure 1.35. In terms of foundry sand reinforcement of the plastic rejects, the results show that 10 percent reinforcement was the most suitable percentage that gave the highest tensile strength of 19.13 MPa. As for regular sand, 10 percent reinforcement was also the most suitable percentage that gave the highest tensile strength of 19.11 MPa. However the trend of foundry sand reinforcement curve in comparison to the regular sand reinforcement curve shown in Figure 1.34, shows that both sands reached a highest tensile strength of 19 MPa at 10 percent reinforcement and then declined with 20 percent and 30 percent, however the degree of decline of the regular sand in comparison to the foundry sand was much steeper. The regular sand declined much worse than the foundry sand, indicating the possibility that the heavy metals within the foundry sand, in fact, have a promising effect on the tensile strength. Foundry sand was shown to be a better reinforcing

% Sand Content

% Sand Content

FIGURE 1.35 Tensile strengths of Composite material with foundry sand and regular sand. (Source: S. M. El-Haggar and L. El-Hatow, "Reinforcing Thermoplastics Rejects with Foundry Sand Waste," Submitted for publication to ASCE (2007).)

element in plastic rejects than regular sand, which is an optimistic observation considering the fact that foundry sand is also a hazardous waste.

When the best percentages of both reinforcing elements were selected and compared, many observations can be seen. First, it can be noted that both reinforcing elements showed improvement from the 0 percent no-reinforcement specimens. Second, the highest tensile strength resulted from reinforcement with foundry sand waste with 10 percent reinforcement, followed by regular sand with 10 percent reinforcement.

Flexural Test To determine the properties of flexural strength of the specimens, tests were done in accordance with ASTM D 790-03 [2003]. The flexural test was performed on the specimens in order to determine the ductility of the specimens as well as their flexural strength. Specimens were machined to dimensions of 127 by 12.7 by 4.5 mm in accordance with ASTM D790-03. Gauge length was 70 mm, with a span to depth ratio of 16. The flexural test occurs on a universal testing machine (UTS). A flexural apparatus was constructed to hold the specimen in place and allows for a three-point bending test. The apparatus was placed and aligned on the UTS machine with two concentric compression plates below and above the apparatus to allow it to function properly. A constant head speed of 2mm/min was used to allow for failure anywhere between 1 to 10 minutes. The flexural strength for the different reinforcing elements showed varying results. The maximum flexural load of the composite material, reinforced with foundry sand waste and regular sand, are shown in Figure 1.36.

The foundry sand reinforcement of the plastic rejects, the 10 percent reinforcement shown to have the highest flexural strength with a maximum flexural

% Sand Content

* Foundry sand ■ Regular sand

% Sand Content

* Foundry sand ■ Regular sand

FIGURE 1.36 Maximum flexural load of composite material with foundry sand and regular sand. (Source: S. M. El-Haggar and L. El-Hatow, "Reinforcing Thermoplastics Rejects with Foundry Sand Waste," Submitted for publication to ASCE (2007).)

load of 34.3 N, which is higher than the 0 percent no-reinforcement value. The regular sand reinforcement of the plastic rejects proved that the 10 percent reinforcement was the best percentage of regular sand reinforcement, with a 33.3 N maximum flexural load. This value was significantly greater than the 0 percent no-reinforcement value. All the regular sand and foundry sand percentage reinforcements were significantly higher than the 0 percent no-reinforcement specimens and thus showed that their addition was enhancing the flexural strength of the specimen by reinforcing it with either regular sand or foundry sand. From Figure 1.36, it is evident that 10 percent foundry sand reinforcement was the best reinforcement in terms of flexural strength and gave the highest value that superseded all other values. The 10 percent regular sand value came in second best.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

Get My Free Ebook


Post a comment