Materials engineers are involved in developing new building materials. The development of low-cost but efficient hydraulic cements is one such area. Here, the materials engineers works on the microscopic level to design cements from optimum blends of materials. One such material is fly-ash that is a waste residue from the combustion of coal in electricity-generating stations. These small particles react with lime and water to produce a cement that is similar in composition to our well-known Portland cement.

A fly ash (spherical) particle embedded in the cement matrix. To the top right of this particle is a sponge-like mass that is the remnant of another fly-ash particle that has reacted. Note the scale: the spherical fly-ash particle is about 4 one-thousandths of a millimetre in diameter.