George Smeed had one of the first cement mills in Sittingbourne c. 1850. He established a Roman cement mill, east of the town, and north of the main railway. This was probably the Sittingbourne cement works of 1860 – 1880, which became Rosher Cement Works between 1880 and 1899.
In the 1850s Smeed introduced Portland cement from a mill situated by Adelaide Dock. In this process, coal was replaced by gas coke and septaria stone by a mixture of chalk and mud. Chalk was extracted from quarries such as the old Highsted pit by hand, then washed at a steam powered washmill and pumped through pipes to the Murston works. In 1896 Smeed leased Murston Cement Works to Webster and Co.
Bullivant’s cement works further along Milton Creek between 1865 and 1895 became the Dolphin Cement Works, which was owned by Burley from 1895 until 1925.
George Smeed leased land to the Burnham, Brick, Lime and Cement Company from 1870 until the 1890s. They had two cement Bottle Kilns at Murston.
The Smeed Dean Company built a new cement works on the old Burnham site between 1900 and 1927. It was sold to the Dunstable Cement Company in 1926 which subsequently merged with others to form The Red Triangle in 1928. In turn this was acquired by the A.P.C.M. group in 1931. The name was changed later to Blue Circle Industries.
Cement manufacture ceased in Murston in 1970.
Joseph Aspdin, who is regarded as the inventor of Portland cement, took out a patent on the process in 1824, but it was Isaac Johnson who fired a mixture of Chalk and Clay at a temperature of 14-1500 degrees centigrade, who is responsible for modern Portland cement.
- Crushed and washed chalk is mixed with marsh clay and water to form a slurry
- This slurry is then fed together with coal into a kiln (at first static bottle kilns, then later rotary kilns)
- This is fired at high temperature to form a clinker
- The clinker is fed into a crushing mill with 2% gypsum and ground into a powder (this is the final cement)
The Rotary Kiln
- A slurry mixture (5 or 6 parts chalk to 2 parts mud and 5 times their joint volume of water)
- This is fed into a long rotating steel tube set at an incline
- Pulverised coal is blown into a brick lined firing zone where the moisture is removed, this is calcining
- This turns the slurry into clinker
- The clinker, once cooled, is fed with gypsum through a rotating ball mill to turn into cement