Cement: The Building Material of Modern Civilisation

Cement is the building material of modern civilisation. Without it there would be no skyscrapers, bridges, tunnels, highways or dams. It is used in almost every type of construction and has been so since 1850 when it began to replace lime as a binder for making mortar and concrete.

The raw materials used to make cement are limestone and clay. Limestone is crushed into a fine powder and mixed with water to form slurry that is fed into a rotating kiln at temperatures of up to 1500C. As the kiln turns, the limestone undergoes thermal decomposition, forming calcium oxide (CaO) which reacts with silica (SiO2), alumina (Al2O3) and ferrous oxide (Fe2O3) from the clay to form cement clinker [1]. The clinker is then ground down with gypsum added to regulate setting times. The result is Portland Cement, named after stone quarried on the Isle of Portland in Dorset that was originally used as aggregate for the product when it was first manufactured in England by Joseph Aspdin in 1824.

More than four billion tonnes of Portland Cement are produced annually around the world and this figure continues to grow steadily as demand increases [2]. It

“Cement” is a word which has become part of our vocabulary. It is the name given to a powdery substance which is obtained by heating limestone and clay in proportionate quantities. With this material you can make ordinary rubble-stone walls into firm structures; with it you can build canal-banks, bridges, and roads; with it the foundations of buildings are made firm.

Until now, however, the general public has known very little about this important material. The purpose of this blog is to change that. In the weekly posts, you will learn about the history of cement, its chemistry, and its various uses in concrete.

Cement is the main ingredient of concrete, which in turn forms the foundations and structures of the buildings we live and work in, and the roads and bridges we travel on. Cement is also used in other building materials such as mortar, grouts, blocks, screeds and concrete products.

In its simplest form, cement is produced by burning a mixture of limestone and clay until they chemically combine to form clinker. The clinker is then cooled and ground with gypsum to produce cement powder.

Cement has been around for at least 12 million years. When the earth itself was undergoing intense geologic changes, volcanic ash combined with limestone and formed a sedimentary rock that we know as Portland stone. Traces of this cement can still be found on the Isle of Portland in Dorset where it was first discovered. There are outcrops of Portland stone along this part of the coast where you can clearly see fossil shells embedded in it, indicating that it was once a sedimentary sea bed.

It is impossible to imagine the modern world without cement. It is used for almost all building purposes, from private housing to the construction of bridges and tunnels, from roads to large dams and canals. As a hydraulic binder, it has no equal.

The discovery of cement goes back to the stone age; the first natural cements were found in various parts of the world: in Scotland, in Ireland and near Naples where an ancient volcano buried Roman buildings under hot ash which later hardened into hard rock. The Romans used this volcanic material to build aqueducts and amphitheatres as well as some of their magnificent villas.

It was not until 1824 that Joseph Aspdin, a bricklayer from Leeds, invented the first artificial cement by burning finely ground chalk with finely divided clay in his kitchen stove. He called this product Portland cement because when it hardened it resembled a type of limestone that came from quarries on the Isle of Portland off the southern coast of England.

Portland cement had two interesting properties: it set under water, which made it ideal for canal linings and harbour construction, and could be mixed with aggregates such as sand and gravel to make concrete. At first concrete was used only for non-load bearing structural elements such

Cement is the vital ingredient in concrete, used for foundations, slabs and walls. It is also used to make mortar, cement render, cement paint on your home and stucco.

Cement is an essential material for construction and it has been used by humans for thousands of years. The history of cement is so entwined with the history of concrete that they are discussed together in this section.

Most people take cement for granted – it’s just ‘that grey powder’ that holds concrete together. But cement has a fascinating history and I hope you enjoy reading about its journey from prehistory to the present day.

Cement is a fine, soft, powdery-type substance. It is made from a mixture of elements that are found in natural materials such as limestone, clay, sand and/or shale. When cement is mixed with water, it can bind sand and gravel into a hard, solid mass called concrete. Concrete is used to make pavements, pipe, roofing tiles, brick and other building materials.

The ancient Egyptians used calcined gypsum as a cement and the Greeks and Romans used lime made by heating limestone and added sand to make mortar, with coarser stones for concrete. The Romans found that a cement could be made which set under water and this was used for the construction of harbours.

In 1756 John Smeaton discovered that mixing powdered clay with lime produced a hydraulic binder (a binder that sets and hardens under water) which was stronger than lime alone. Joseph Aspdin in Leeds patented his ‘Portland Cement’ in 1824; this was the first material to resemble modern Portland cement and contained four main ingredients: chalk or limestone; clay; shale or claystone; coal dust. In 1843 Isaac Johnson further improved the process by burning finely ground chalk with finely divided clay in one of the earliest rotary