Concrete density is likely to achieve the desired properties and functionalities. It differs for every construction project based on their plans and designs. However, one of the common preferences is high-density concrete made from various high-density man-made or natural aggregates.
It can be used in a wide variety of applications by adjusting the admixtures. In this article, you’ll be explained what high density concrete is, its composition, mix proportion, and advantages. Continue your reading to know more:
What is High-Density Concrete
High density concrete, also known as heavyweight concrete, includes a density range of between 6000 to 6400 kg/m3. This is approximately 50% higher than conventional concrete. This type of concrete primarily includes aggregates such as iron ore, hematite, magnetite, or ilmenite. High density concrete is fundamental for radiation shielding, counterweights, and other applications where the high density is essential.
It exhibits better shielding properties, acting as a protective layer against harmful radiations, including neutrons, X-rays, and gamma rays.
Composition of High Density Concrete
As mentioned earlier, high density concrete can be achieved through natural or man-made aggregates like magnetic or barite. It may also include manufactured aggregates such as lead shot or iron.
The level of density will depend on the types of aggregates we use in the composition. When using barites, the density can range up to 3500 kg/m3, whereas the magnetite will be 3900 kg/m3.
Beyond this range, the iron or lead shot is used as an aggregate to achieve densities of about 5900 kg/m3 and 8900 kg/m3. Concrete with heavy aggregates like iron ore and magnetite helps increase the concrete density and fight against radiation.
Materials and Mix Proportion of High Density Concrete
The constituent materials like water, cement, and admixtures are used in high density concrete, which are all the same for normal density concrete too. However, the aggregates can vary and may require special care and attention during batching, mixing, handling, transporting, and placing.
The desired density is achieved through high-density aggregates such as iron oxides. Before getting into the process, some considerations will be taken into account, such as intended use, availability, physical and chemical properties, and cost.
Concrete densities range from 3700 to 3800 kg/m3 and are obtained using certain typical aggregates with particle relative densities of at least 4500 kg/m3. The densities of 4800 kg/m3 utilise aggregates with a particle relative density of at least 6000 kg/m3.
With naturally occurring aggregates, concrete densities of approximately 4000 kg/m3 can be obtained. In contrast, with man-made or synthetic aggregates, densities above 4000 kg/m3 can be obtained.
Properties of High Density Concrete
The properties of high-density concrete depend on the types of aggregates used. For instance, typical densities of specific aggregates are as follows:
| Type of Aggregate | Aggregate Relative Density | Aggregate Bulk Density, kg/m3 (pcf) | Concrete Density kg/m3 (pcf) | Fixed-water percent by weight |
| Geothite | 3.4 – 3.7 | 2080 – 2240 (130 – 140) | 2880 – 3200 (180-200) | 10 – 11 |
| Barite | 4.0 – 4.6 | 2320 – 2560 (145 – 160) | 3360 – 3680 (210 – 230) | 0 |
| Limonite | 3.4 – 4.0 | 2080 – 2400 (130 – 150) | 2880 – 3360 (180 – 210) | 8-9 |
| Steel punchings or shot | 6.2 – 7.8 | 3860 – 4650 (230 – 290) | 4650 – 6090 (290 – 380) | 0 |
| Ferrophosphorus | 5.8 – 6.8 | 3200 – 4160 (200 – 260) | 4080 – 5290 (255 – 330) | 0 |
| Magnetite | 4.2 – 5.2 | 2400 – 3040 (150 – 190) | 3360 – 4170 (210 – 260) | – |
| Hematite | 4.9 – 5.3 | 2880 – 3200 (180 – 200) | 3850 – 4170 (240 – 260) | – |
| Ilmenite | 4.3-4.8 | 2560 – 2700 (160-170) | 3520 – 3850 (220 – 240) | – |
If you want to achieve the concrete densities of 5000 kg/m3, then steel punchings or shot can be used.
Uses of High-Density Concrete
Due to its unique properties and functionalities, high density concrete can be used in a wide variety of applications. Here are some common uses such as:
Radiation Shielding: High density concrete can fight against harmful radiation such as neutrons, X-rays, and gamma rays. The usage of heavy aggregates such as iron ore and magnetite prevents penetration to the other side.
Counterweights: High density concrete is an ideal choice for counterweights, as it helps distribute weight evenly to the structures. When using it in strategic locations, stability can be improved with reduced stress on other components.
Underwater Structures: Concrete with high strength and density can make it an ideal choice for underwater structures. It can withstand the immense pressure created inside the water column. Its fast curing and resistance to corrosion are additional advantages.
Advantages of High Density Concrete
Here are the lists of advantages that you can expect from high-density concrete:
Enhanced Weight-bearing Capacity: Higher-density concrete supports heavy loads without lifting the structural stress and dimensions. This can be a perfect choice for structures where they have limited space but need to withstand significant stresses.
Reduced Thermal Cracking: High density concrete has excellent thermal conductivity when compared to normal concrete. It can dissipate heat and reduce the risk of thermal cracking when the concrete is exposed to rapid temperature fluctuations.
Space Savings: As known, high-density concrete has an increased strength-to-weight ratio. It helps create more compact structural elements, resulting in significant space savings. This is best suited for urban areas where the land space is very limited.
Cost Cutting: The initial investment of high-density concrete may be higher than that of conventional concrete due to the requirement for heavy aggregates. But it benefits you in several ways, like reduced thermal cracking and potential space savings.
Disadvantages of High Density Concrete
Reduced Workability: Compared to normal concrete, high-density concrete is quite difficult to mix, transport, and place. It drastically slows down construction work and increases labour costs.
Limited Availability: Heavy aggregates are expensive and are hard to obtain in some regions. It constrains the usage of aggregates during the manufacturing process.
Final Lines
High-density concrete can be seen in many construction projects as it offers numerous advantages to the structures over normal concrete. Choosing quality aggregates helps you achieve the desired properties. Hopefully, with this article, you can understand its properties, mix proportions, and advantages in detail.