Tag Archives: Tensile Strength

Titanium – What is It and What is It Used For?

Photo of titanium
titanium metal alloy, used in industry, super resistant metal. Photo: iStock

Overview

In the last few years, there has been a lot of buzz about the metal known as titanium. The reason is that it has quite a few properties that make it useful in everyday life.

It is strong, lightweight, and corrosion-resistant among other things. It is most popular for being used to create aircraft parts and car engine components; however, there is so much more to this metal than meets the eye. 

People have used titanium for thousands of years. Only recently we have begun to understand exactly how useful this mineral can be. It was found to be extremely useful for military stealth functions, starting with the famous SR-71 reconnaissance aircraft, due to the metal’s strength and high-temperature resilience (as we will discuss below) and the fact that it is lightweight (e.g. in this case, functioning as a very strong material but light), it was perfect for this spy plane. 

Let’s take a look at some interesting facts about titanium.

Properties Stronger than Steel

You might have heard that titanium is as strong as steel. While this is not entirely true, it is close enough to be significant. To begin with, strength is not a single chemical property of a material. But for simplicity, let’s treat it as one. 

The tensile strength (measurement of a material’s elastic stress when a load is placed on it – how much it can withstand before starting to stretch or pull out before breaking apart) of steel is around 100 gigapascals (GPa) – the unit of measurement of tensile strength. (One pascal is equal to 1 newton of force per square meter).

The tensile strength of titanium is about 60 GPa. Therefore, steel is stronger than titanium. However, the thing to note here is that titanium’s strength is applied only at a very specific point. Let’s say that you have a piece of metal that has a high tensile strength across its entire surface. This does not make it stronger than a piece of metal with a lower tensile strength applied at a specific point.

Titanium Symbol
Titanium (Ti) has 22 electrons and 22 protons. Photo: iStock

Chemical Properties of Titanium

Titanium has a lot of unique properties that make it special. It has a very high melting point (more than 3,000 degrees Fahrenheit). Because titanium resists oxidation at high temperatures, it is often used in high-temperature applications.

Oxidation is the loss of electrons, resulting in the titanium atoms becoming vulnerable to combining with other atoms; subsequently changing their properties and compromising the material.

A perfect example of using titanium for its resistance to oxidization at high temperatures is that it makes an excellent material for the SR-71 since this plane could fly at Mach 2.5, which is close to 2,000 miles per hour. This metal is also corrosion-resistant. This means that titanium is very useful when exposed to water or air. 

Titanium has an atomic number of 22 and an atomic weight of 47.867, which means it has 22 protons and approximately 48 protons and neutrons, respectively.

Everyday Uses of Titanium

Titanium is being used in many different industries, and there are several everyday uses of titanium that you may not be aware of. This is because titanium is lightweight, strong, and corrosion-resistant, making it the perfect material for sports equipment.

    • Sports equipment – If you are a sports fan, you may have seen athletes wearing titanium-containing sports accessories. 
    • Medical equipment – If you ever get an MRI scan, you may be inside a machine that is made of titanium. This is because titanium is very safe to use around living tissue and can be sterilized easily. 
    • Marine parts – If you own a boat, you may be surprised to learn that the propellers and rudders are often made of titanium. This is because it is strong, lightweight, corrosion-resistant, and does not affect water flow. 
    • Water and air purification – You may have seen pictures of large towers in cities. These towers are used for water purification and are often made of titanium. 
    • Construction – Buildings, bridges, and other infrastructure are often constructed using titanium. This is because it is highly corrosion-resistant and very strong. 
    • Food packaging – If you have ever eaten food that was in a pouch, there is a good chance that the pouch was made of titanium.

How is Titanium Produced?

Titanium is made through a process known as the Kroll process. – First, titanium ore is mined and then sent to a smelter where it is heated to extremely high temperatures.

The resulting molten metal is then sent through a chemical reduction process which removes oxygen and other impurities. The molten metal is then cast into ingots and then rolled into long bars. These bars are then drawn through a press that elongates them and makes them thinner. Finally, the bars are shaped into their final forms and then sent to be coated or processed further.

Problems with Manufacturing and Existing Processes

As you have read, titanium is a very versatile material that can be used in a wide variety of industries. However, there are some issues with the current methods of manufacturing this mineral that needs to be addressed. 

    • High costs – Currently, the process of producing titanium is very energy-intensive and expensive. The cost of the metal itself is also quite high, making it costly to produce certain products. 
    • Contamination – The process of manufacturing titanium is quite complex, and there is a risk of contamination in certain areas of the process.  
    • High purity requirements – Another issue with titanium is that it has very high purity requirements. This means that the resulting metal can be very impure even after the purification process. 
    • Difficult to produce large quantities of titanium in the quantities needed for the industries that use it.

Concluding Words

Titanium is a very versatile metal that can be used in a wide variety of industries. However, due to its high costs and difficult manufacturing process, it is often difficult to produce large quantities of titanium. With that said, titanium is used for very specific functions. This article has explored the many uses of titanium and the process behind its manufacture.

 

What is Concrete?

What is Concrete?

Concrete Blocks
Photo by uve sanchez on Unsplash

Ever notice that just about every building has a concrete foundation?  There is a very good reason for this and it is not about aesthetics. Concrete has enormous compressive strength, meaning that it is an excellent material for holding up the weight that is above it. 

Concrete is not just used for foundations, but also for columns, and beams. slabs and just about anything where there is a load-bearing issue. Load bearing means an element that supports the weight above it. The amount of weight that the load-bearing element would support would depend upon how many concrete columns (or other concrete supporting materials) are available to support the whole load.

For example, a 30-story building has 10 supporting columns on the ground. That would mean that the weight is evenly distributed across each of the 10 columns or mathematically speaking, each concrete column would support 0.333 (10/30) of the load (building).

Another probably more identifiable example is the load-bearing walls in a house. If you live in a house, you have probably become aware of where your load-bearing walls are. These are the walls that actually hold up the house; however, for frame houses, concrete is not the usual load-bearing material, but heavy wood or steel instead. 

A concrete column
Concrete column supporting the highway above. Photo by SS

In short, concrete is an excellent source for withstanding the heavy forces that are above it or more specifically, as an excellent compression material.

Did you know that concrete also gains more strength as it ages? With that said, let’s take a look at just what this compressive material is actually made of.

What is Concrete Made Out of?

Concrete is a mixture of air, water, sand, and gravel and the percentages of these elements are usually 20% air and water, 30% sand called fine aggregates, and 40% gravel, with 10% being cement; that is, 10% being the ‘glue’ that keeps all those other materials together. Remember, from our article on cement, it is just the binding material for the assembly of concrete. When the cement is mixed with water, it is called paste

This proportion is called the 10-20-30-40 Rule; however, the exact percentages of the materials can vary depending on the combination of the concrete mixture, including the type of cement and other factors that we will explain in this article.

How are the Proportion of Materials that Form Concrete Determined?

So we know that concrete is a mixture of paste and aggregates and sometimes rocks. The paste coats each of the aggregates and as it hardens (the process is called hydration), concrete is born until it becomes a rock-solid mass, capable of withstanding a load much heavier than itself, but if the proportion of water and paste is not correct, this rock-solid mass can deteriorate causing unwanted and potentially dangerous consequences.

The trick is to carefully proportion the mix of the ingredients and much of it depends on the ratio of water to cement and this ratio is calculated by the weight of the water divided by the weight of the cement. A low water-content ratio yields high-quality concrete, so it is best to lower the ratio as much as possible without sacrificing the integrity of the concrete.

If the ratio results where there is too much water in the mixture, the aggregates become thinned out, resulting in weakening the concrete and we can figure out what that would mean.

Conversely, If there is not enough water in the mix, the water will evaporate too fast, compromising the integrity of the concrete and resulting in it being weak as well.

Construction worker worket pours concrete into rebar frame
Construction worker pouring concrete into steel rebar frame. iStock

What is the Strongest Concrete Mixture Ratio?

1:3:5 which is cement and aggregates (in this case, the aggregate is broken into sand (3) and gravel (5), and this is considered the ratio that would create the strongest concrete.

What Happens if the Wrong Mixture of Concrete is Used?

If the ratio of the concrete mix is not done correctly, there can be a variety of problems, such as compromising its integrity which can lead to disastrous results.

Cracking

Excessive water content, inadequate curing, or incorrect proportions of cement, aggregates, or water can contribute to cracking. These cracks can compromise the durability of the building and allow moisture penetration, leading to further deterioration over time.

Reduced Strength

Concrete strength is a critical factor in ensuring the structural integrity of buildings. If the concrete mix has an incorrect ratio of the required additives, it may not achieve the strength needed to maintain its load. This can compromise the load-bearing capacity of the structure and lead to collapse or deformation under normal loads.

Ultimately, using an improper concrete mixture poses safety risks to occupants and users of the building. Structural failures or deterioration can lead to accidents, injuries, and even loss of life in severe cases.

Champlain Towers Building Collapse

Surfside florida condo collapse
Miami Beach Surfside, FL, June 26, 2021, Champlain Tower collapse most probably due to concrete deficiencies.

One recent incident occurred in Surfside, Florida where the Champlain Towers collapsed on June 24, 2021, and 98 people lost their lives.

The investigation is still ongoing but they have found structural defects in the design of the pool, as well as compromised integrity of the columns that supported the building.

How Much Time Is Allocated Before the Finished Concrete Is Used at the Construction Site?

There is a limit to how long the concrete can be poured after it is mixed. In the US, the limit is 60 minutes from the time the water mixes with the cement to the time of delivery to the construction site.



A safe time frame is up to 90 minutes, then the integrity of the concrete will start to deteriorate. That is why we see concrete mixers right at the construction site as no time is lost between the mixture and the pouring.

What About Reinforced Concrete?

As the name applies, when steel (usually using steel bars, called rebars) is placed inside the slab where the concrete is going to be poured, it reinforces the strength of the concrete.

How Does Rebar Reinforce Concrete?

We have been discussing compression strength; that is, how strong the material is when a heavy load is placed on it, but we haven’t discussed tensile strengthwhich is the opposite of compression.

Tensile strength represents the strength a material can endure when a force tries to pull or stretch it out. The reason why compression is so important when using concrete is that that is its main purpose – to hold up heavy loads, but concrete does have a limit on how much pull can be leveled on it as well, and there are situations where the tensile strength of concrete is put to the test. The weather being one factor, but there are more.

Enter Steel

Reinforced Steel Slab
A construction worker working on a reinforced steel slap where the concrete will be poured. Photo by SS.

By integrating the rebars inside the concrete, the concern about stretching the concrete is greatly minimized. The combination of concrete and its accompanying reinforcing steel bars successfully manages these situations, because of steel’s high tensile strength; hence, you have a perfect storm of compressive and tensile strength in reinforced concrete (RC).

What Happens if the Reinforcing Steel is Not Inside the Concrete?

Cracking of the concrete surfaces can occur, subsequently causing aesthetic issues, but if the tensile yield is really great, (e.g. a strong pull on the concrete) the situation can become unsafe, so without the steel rods to compensate for this pull, you will find cracks in the concrete or worse.

Conclusion

Concrete is a mixture of sand, water, aggregates and cement. The amount of any of these elements will determine the strength of the concrete. Timing also plays a role as the concrete must be readily mixed within 90 minutes max, but 60 minutes is the usual requirement before being poured into its foundation or another element such as a column or slab.

By placing steel bars which is a mesh of steel wires (rebar) inside the concrete, the tension issue is resolved by aiding the concrete under tension.

So the next time you are walking in a building, especially a large structure such as a skyscraper, give thanks to the materials that allow you to be there, as well being thankful to the engineers who allowed it to happen!