Granite. Bronze. Steel. ----Properties comparison. Heat Resistant/ Thermal Movement.
Thermal Movement in New York City: NYC is host to a wide range of different weather conditions. The weather is often fickle, and changes can be sudden; the sweltering Summer months can be notoriously hot and humid, while temperatures during the City’s long Winter usually hover below freezing.
Year-Round climate range: 25-84 oF.
Specific Heat Capacity
“Specific heat is the amount of heat required to change temperature of one kilogram of a substance by one degree.”
Acidity of rain in New York: 4.22-4.40
Humidity in New York : 56-87% (Summer); 68-77% (winter)
Of all the building stones, granite is the least susceptible to acid rain because its composition is of feldspar and quartz, both of which resist attacks of acid.
Bronze coin gets its green color from the natural patina formed on its bronze surface.
Bronze resists corrosion and metal fatigue (structural damage that occurs through constant use) more than steel. It is particularly resistant to seawater corrosion.
All steels and low-alloy steels rust in moist atmospheres. In some circumstances, the addition of 0.3% copper to carbon steel can reduce the rate of rusting by one quarter or even by one half.
Patina of metal materials protect them from further corruption
According to the American Galvanizers Association, galvanized steel resists corrosion up to 100 times better than uncoated steel.
All galvanized steel has a matte-gray appearance. Zinc coating applied by using electro-galvanizing is smoother than galvanized steel made with batch or continuous galvanizing and allows for a higher quality finish when painted.
The zinc coating on galvanized steel is resistant to cracking and loss of adhesion when the steel is formed into a product.
The zinc coating does not require special handling to protect it during transport or use. It is extremely durable and resistant to scratches from abrasion.
Bronze, as an alloy, is harder than copper and therefore can be applied to more rigorous uses. The hardness of a metal is designated with a numerical value using the Rockwell hardness scale. Silicon bronze has HRB 50, where B is the class of hardness and 50 is the specific value. Phosphor bronze has HRB 45 and manganese bronze has HRB 80.
Bronze Physical Attributes
Bronze is harder, stronger in compression and more resistant to corrosion than the brasses. Bronze that will not be exposed to extremes of weather can be protected from corrosion by warming it to slightly over 212°F (100°C) in an oxygen atmosphere. A thin layer of oxide or patina forms to prevent further oxidation.
Bronze Temperature Properties
At forming temperatures below 1290°F (700°C), properties depend primarily on compacting pressure. At higher temperatures, properties depend first on temperature, although heat treatment beyond 30 min has minor influence. The melting point mostly depends on the components inside the bronze alloy and is around 950°F.
In terms of its physical properties granite is a unique material. These properties lending
uniqueness to granite are:
Granite has almost negligible porosity ranging between 0.2 to 4%.
Granite is highly stable thermally, therefore shows no changes with the change in temperature.
Granite is impervious to weathering from temperature and even from the air borne chemicals. It
is the high resistance to chemical erosion that makes granite useful for making tanks to store
highly caustic material.
The coefficientofexpansion for granite varies from 4.7x106– 9.0x106(inch x inch).
Granite shows consistency in color and texture.
It is the hardest building stone and hardness of granite that lends it excellent wear.