Note on Sorel Cement

Sorel Cement

Sorel cement or Magnesium oxychloride cement is prepared by mixing MgO powder with MgCl2 . Sorel cement is used as a fast curing cement for some applications including stucco, flame retardant coatings and molded cement objects. There is considerable controversy in the literature as to what chemical reaction is responsible for the setting reaction of Sorel cement.

Experimental studies have shown that the setting reactions of Sorel cement is sensitive to X-Ray radiation. The setting time is found to increase on exposure of this cement to X-Ray radiations. This makes it difficult to examine Sorel Cement samples using X-Ray spectrometer. Apart from X-Ray Radiation, Polarized Laser light radiation and a Strong DC electric field are also found to affect the crystallization of Sorel Cement.

The advantages and disadvantages of Sorel Cement are as follows

Advantages:

• Rapid Hardening – reaches 80% of ultimate strength in 1 day
• Lightweight cement (Density – 1600 to 1800 kg/m3) but strong in terms of compressive strength and rupture strength, when compared to OPC.
• Less alkaline, when compared to OPC.
• Good abrasion resistance (around 3 times that of OPC) making it suitable for manufacturing floor tiles.
• Good adhesion properties.
• Excellent fire resistance making it suitable for making fire resistant wall boards.
• Good thermal insulation
• Energy efficient and environment-friendly material which can be used in the field of Sustainable development.

Disadvantages

• Poor water resistance – compressive strength may decrease up to 80% after long exposure in ordinary moisture conditions.
• High moisture absorption and efflorescence, precipitating out the gel and modifier chemicals.
• Undergoes volume expansion and contraction easily, leading to drying shrinkage, expansion crack and warping deformations.
• Poor corrosion resistance as the chloride ion accelerates corrosion of reinforcing steel, leading to expansion cracks.
• Large scale production of this cement is limited due to scarcity of raw materials.

Current Applications of Sorel Cement

• Making packaging materials –usually framed and fully enclosed boxes.
• In energy efficient buildings, it is used as interior walls, closet boards, door and window components, floor, stair handrail, chute, botanical garden construction etc.
• In transportation, it is used in road isolation facilities, road signs etc.

Research works on Sorel Cement

• The main concern regarding the use of Sorel Cement is its poor resistance to water. So a lot of research has been going on to identify materials which can improve the water resistance of Sorel Cement, thus decreasing chances of reinforcement corrosion in concrete. Materials like low temperature rice husk ash, fly ash, diatomite, wollastonite tailings, soluble phosphate, Urea Formaldehyde resin composite admixture, Chlorine ion capture agents are found to have a positive effect on improving the water resistance of Sorel Cement. Some research works also recommend the use of epoxy resins as a coating on the cement products to improve water resistance.
• The warping and cracking of Sorel cement can be controlled by strict quality control of raw materials used for production. A combination of rice husk ash and Urea formaldehyde resin composite admixtures in Sorel cement gave a satisfactory product with no warping and 95 % compressive strength at damp conditions.
• Little research has been done on the potential of Sorel cement to be used as a substitute for OPC.
• In one research ,it was found that the setting reaction of Sorel Cement can act as a sink for Carbon dioxide by consuming CO2 making it more environment friendly.
• In 2008, an interesting approach was developed by the UK-based company Novacem in collaboration with Lafrange, to manufacture such cements from magnesium silicate rocks (e.g., olivine or serpentine), of which reservoirs are enormous and estimated to be more than 10,000 billion tons. Even though the manufacturing process was CO2 neutral, it still involved carbonation of magnesium silicates under a temperature of 200°C and a pressure of 180 bars to produce Magnesium Carbonate.
• Addition of OPC to Sorel cement as an additive (up to 20% by weight of Sorel Cement) accelerated initial setting time but retarded the final setting of the Sorel cement. The water tightness of the cement also improved with addition of OPC.

Reference

• Sorel Cement Reactions and their Kinetics- Terry A. Ring and Eric Ping
• The application review of magnesium oxychloride cement-Hongxia Qiao, Qianyuan Cheng, Wang Jinlei and Shi Yingying
• Recent Progress in Green Cement Technology Utilizing Low-Carbon Emission Fuels and Raw Materials- Ali Naqi and Jeong Gook Jang
• Effects on Setting, Strength, Moisture Resistance and Linear Changes of Sorel’s Cement on Mixing Portland Cement as an Additive- Ritu Mathur, M.P.S. Chandrawat And Sanjay K. Sharma