The Effect of Impurities on the Physical Properties of Oxychloride Cements

The rapidly increasing use of Stucco, a cement made by mixing magnesite with a solution of magnesium chloride, as an exterior for dwelling houses has given rise to an interesting study of its chemical and physical properties. As usually applied, the stucco is made according to the specifications of the Committee on Specifications for Plastic Magnesite, which recommended the following mixture to be standard: One part by weight of plastic calcined Magnesite; Two parts by weight of Standard Ground Silica; Five parts by weight of Standard Ottawa Sand. This is then mixed with a 22 degree Baume solution of magnesium chloride to the proper consistency. Various colored oxides may be added to color the cement as desired. The cementing properties of such mixture are due to the formation of an oxychloride compound of magnesium by the interaction between magnesite and the magnesium chloride solution, the sand acting only as a filler or as an attachment for the cement crystals