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How can you tell whether cavities in a casting are due to porosity or to shrinkage?
Porosity is a defect, which results from air entrapment in the molten metal due to turbulent flow causing air bubbles. Usually, this defect is characterized by smooth and spherical pores, but if rough and angular it is most likely as a result of shrinkage dendrites. The mechanical properties associated with shrinkage is the thermal expansion of the molten metal when it solidifies and cools to room temperature, if the riser isn't properly designed to accommodate shrinkage, there would be dimensional changes and are usually in form of cracks.
What is stronger than concrete?
steel
How heavy is concrete per cubic meter?
Concrete weighs about 150 pounds per cubic foot. Can't do the math but that is about 4500 pounds.
Pre stressed concrete compared to Post tensioned concrete?
Prestressed concete made using high tensile wires which is stressed (as per the design load) before concreting, and post tensioned concrete made of Strands covered with duct, in this, wires/strnads are stressed after concreting then the ducts are grouted using cement slurry..
In the Civil Engineering field Materials Engineering is the development of what?
In the field of civil engineering, material engineering is the development of concrete, mix asphalt concrete, and strong metals such as steel. Alloying is another aspect of materials engineering.
Shrinkage of concrete?
The loss of water results in reduction of volume of concrete this is known as shrinkage of concrete.Prevention of shrinkage in concrete:Low moisture contentSize of aggregates used.
What is a shrinkage joint?
A shrinkage joint, or control joint is a separation cut with a finishing handtool into wet concrete sidewalks to 1/4 of the depth of the concrete. Since concrete shrinks a tiny bit as it cures, little tiny cracks may develop . . . the shrinkage joints make those cracks appear in the nice straight joints, thus improving the looks of the new concrete walk. Shrinkage joints may also be cut in after the concrete has cured long enough to stand on (several hours) with a concrete-cutting saw.
Is cracking at joints acceptable after new pour of concrete?
Cracking at expansion joints is always acceptable and is the reason for the joint itself. There are two kinds of cracks, pretty ones and ugly ones! Ugly ones are random cracks where the concrete relieves itself from drying shrinkage in a random location within the slab of concrete which is normally not appealing to the eye. Expansion joints are placed at predetermined intervals within the slab where random cracks are weakened planes in locations where cracking is predicted prior to fresh concrete placement. All concrete shrinks when it dries, the larger the slab, the greater the overall shrinkage. When the tensile strength of drying shrinkage exceeds the tensile strength of the concrete, cracking will occur. Lets just hopes it cracks in a spot where we planned it instead of a location where didn't. By the way, joints should be cut at least 25% of the depth of the slab.
What is the influence of calcium stearate on the shrinkage of concrete?
Calcium stearate is used to control effloresence in concrete. I don't believe there is any effect on shrinkage. However, it is often added to other concrete admixtures, like water reducers. Those products can effect shrinkage, but usually they help to reduce it.
Does drying clothes on high heat setting cause shrinkage?
Yes, drying clothes on a high heat setting can cause shrinkage because the high temperature can damage the fibers in the fabric, causing them to contract and shrink.
Why shirinkage in concerete?
Shrinkage in concrete occurs due to the loss of moisture during the curing process. As the water evaporates, the concrete material contracts and reduces in volume. This shrinkage can lead to cracks forming in the concrete if not properly controlled. Factors such as mix design, curing methods, and environmental conditions can influence the extent of shrinkage in concrete.
What are the types of shrinkage in concrete?
the amount u put aw aw yea lick
What does shrinkage temperature steel do?
Steel bars laid in concrete to reduce cracking do to temperature change
What is shrinkage test in garments?
Shrinkage test in garments is a process used to determine the amount of shrinkage a fabric or garment will experience during laundering. It involves washing and drying the fabric or garment according to specified conditions and then measuring any dimensional changes that occur. This test helps manufacturers assess the potential for shrinkage in their products and make adjustments as needed.
How thick can you pour concrete when drying?
The thickness of concrete that can be poured when drying typically ranges from 4 to 12 inches. Thicker pours may require additional support or reinforcement to prevent cracking.
What has the author Perry H Petersen written?
Perry H. Petersen has written: 'Shrinkage and creep in prestressed concrete'
Difference between type k cement and cement fondue?
Type K cement is slightly expansive and helps reduce the shrinkage issues associated with normal cement in concrete mixes. Cement fondu is an accelerated cement that provide concrete higher earlier strength. It does not specifically compensate for shrinkage
