TANZANIA - #likelafargeholcim

For building tips and information, follow us on

What is pozzolana and why is it used in cement?

Pozzolana is an ingredient in cement

One of the core ingredients of cement is pozzolana, or pozzolanic ash. It is a natural material that comes from volcanic ash and it contains silica, which gives pozzolana cementitious properties. This means that pozzolana can react with certain elements to form a hard, binding material.

Volcanic ash was first used by the ancient Greeks as a building material as early as 500 BC. However, it was the Romans that really pioneered the use of pozzolana as a binding agent to hold stones together. This allowed the Romans to build tall buildings and underwater structures, some of which still stand today, more than 2100 years later.

The substance is widely used in the manufacture of cement, including at LafargeHolcim Tanzania’s Tembo cement facility in Mbeya. Pozzolana has a number of physical properties that make it perfectly suited to creating cement, which we will outline below:

Properties of pozzolana

Pozzolana is used in cement for a number of reasons. When water is added to cement, it produces lime, or calcium hydroxide. Pozzolana reacts with this lime to form a strong bond with the other materials. On its own, lime does not contribute to the strength of concrete. The reaction between these two elements produces calcium silicate hydrate which is a strong bonding material.

By reacting with lime, pozzolana increases the strength of concrete. It also makes the concrete more dense, which is good for a structure’s durability. This reaction also decreases the efflorescence of concrete – the migration of salts to the surface of the concrete. Pozzolana is an important material for numerous reasons

Pozzolana can include the following elements:

  • Fly ash
  • Slag
  • Silica fume
  • Metakaolin
  • Vitrified calcium alumino-silicate

Of these elements, fly ash is the least reactive to lime and silica fume is the most reactive. This reaction determines the curing time of the concrete. These elements help to give cement it’s fine, powdery texture which is what makes it a good bonding agent when added to water and aggregates.

Other uses of pozzolana

Pozzolanic substances have a range of uses in construction, including the following:

  • Used in the manufacture of Portland Pozzolana cement (PPC).
  • Used as a soil-stabilisation material.
  • Used as a filler mineral in asphalt roads, helping to fill voids in the tar.
  • Used as a component in geopolymers, such as ceramics.
  • Used in roller-compacted concrete dams.
  • Used in the manufacture of concrete bricks.


LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 


LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.


At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.


Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

Tembo SupaSet cement used in construction of Wanging’ombe District Hospital

LafargeHolcim Tanzania is supplying Tembo cement for the construction of a new hospital. The Wanging’ombe District Hospital is currently being built under the supervision of the district engineer. Tembo SupaSet is being used to construct the foundations of the new healthcare facility. The Wanging’ombe District Hospital is located in Wanging’ombe – one of six districts …

Things to know about mortar for bricklaying

The two most common types of mortar used for bricklaying are cement and lime mortar. They have different properties and strength characteristics, so it is important for contractors to which one to use for a project. LafargeHolcim Tanzania manufactures a few cement products that are suitable for use as mortar in brickwork. These are Tembo …

Things to consider when pouring concrete during the rainy season

Construction projects are planned and executed all-year-round. This means that contractors need to build in some extreme weather conditions, from searing hot and dry temperatures to windy and rainy weather. These factors can all affect concrete and how it cures, but the rainy season can be particularly hard because it brings water and wind. Contractors …

How to prevent salt damage to your concrete structures

Salt is a natural mineral that can sometimes end up in your concrete mixture. It can either be present in the sand and aggregate or it can end up in the concrete if you are building in a seaside environment. It appears as white streaks or powdery crystals on the surface of cured concrete. The …

Inspection checklists for pouring concrete

All construction projects should be inspected at least once a day. This will ensure that the quality of the structure is up to standards and that the work is being done properly. An inspection is especially important when pouring concrete. There are a number of checks that should be performed to record the process and …

Building Materials Centre paving the future of Tanzania

The future holds many challenges for Tanzanians, especially in the infrastructure sector. Luckily, LafargeHolcim Tanzania understands these challenges and can help Tanzanians prepare to overcome them. We offer training programmes and free knowledge-sharing sessions at our Building Materials Centre in Dar es Salaam.  LafargeHolcim Tanzania shares the interests and concerns of the communities around us. …

Avoid these common construction mistakes

A building’s quality and resilience are not only affected by the materials used to construct it. Workmanship and building techniques also determine how well a structure will be completed. Poor concrete construction methods will result in a badly-built structure. Construction mistakes are made when contractors are not trained properly or when they are negligent. Poor …

Update your business space with concrete

Concrete is a wonderful building material. Not only is it perfect for the structure of buildings, but it can also be used in a decorative way. Business owners, restauranteurs and retailers should consider incorporating concrete into the interior design of their workspaces. This will modernise and improve the look and feel of the office, restaurant …