Factors Influencing the Phase Composition and Properties of Magnesium Oxychloride Cements

Tawfik, A.; Serry, M. A.
March 2013
Interceram: International Ceramic Review;Mar2013, Vol. 62 Issue 1, p25
Trade Publication
Precursor MgO/MgCl2 and H2O/MgCl2 molar ratios were varied (from 3 to 6 and 12 to 24, respectively) to determine their effect on the phase composition and properties of pure magnesium oxychloride (MOC) cement pastes after air curing. XRD and DTA were applied to reveal the phase composition of hydrated pastes. The water required for workability and initial and final setting times were determined to assess the cement's hydraulic properties. Physico-mechanical properties of hardened samples were also evaluated by means of bulk density (BD) and compressive strength (CS) measurements. Selected samples, doped with 0-1.33 mass-% of sodium hexametaphosphate (NaPO3)6 were investigated for water resistance after 7-14 d immersion in water. This was done by comparing BD values and computing a compressive strength retention ratio (CSRR), as well as examining changes in component functional groups (by FTIR spectroscopy) after water curing. he results indicate that increasing the molar MgO/MgCl2 ratio from 3 to 6 leads to a gradual increase in the amount of water needed for workability and consequently, H2O/MgCl2 molar ratio, with little change in the range of initial and final setting times (25-35 and 120-180 min, respectively) for all samples. CS increased to its maximum value at a molar ratio of 3.5 MgO/MgCl2 and then gradually decreased to a minimum as the ratio increased to 6. Meanwhile, BD lowered gradually from ~1.6 to 1.0 g/cm³. The XRD and DTA investigation revealed that with molar MgO/MgCl2 ratio 3-3.5, phase-3 [3Mg(OH) 2·MgCl2·8H2O] is the main product component with lesser amounts of phase-5 [5Mg(OH) 2·MgCl2·8H2O] and chlorartinite [Mg2 (OH)ClCO3·3H2O] also detected. The latter phase predominated as the molar ratio increased up to 6.0 at the expense of phase-5 and phase-3, mainly due to the relatively higher stability and resistance of phase-3 against atmospheric CO2 gas than phase-5. Doping of selected MOC samples, having MgO/MgCl2 molar ratio 3.5, with up to 1.33 % SHMP led to a gradual decrease in compressive strength and CSRR of the air-cured samples and a decrease of bulk density. Water resistance of these samples improved with increased SHMP up to 0.66-1.33 %, (~1.0 %), which gave the lowest BD (<1.0 g/cm³) and the highest CSRR (1.0-1.4), after water-curing up to 14 d. This is mainly attributed to phosphate anions stabilizing the major MOC P-3 phase at the expense of -OH groups and discouraging dissolution in water, as confirmed by the FTIR spectra.


Related Articles

  • Study on preparation and mechanical properties of magnesium phosphate cement. Runqing Liu; Dingqiang Chen; Tianbo Hou // Advanced Materials Research;2014, Vol. 1049-1050, p416 

    The orthogonal experiment method is utilized in this paper to get a comprehensive analysis of the compressive strength of magnesium phosphate cement (MPC) to prepare the cement with the best performance. What's more, a further study is conducted on the compressive strength of paste and the...

  • Effects of Material Ratio, Fly Ash, and Citric Acid on Magnesium Oxysulfate Cement. Chengyou Wu; Hongfa Yu; Jinmei Dong; Lina Zheng // ACI Materials Journal;May/Jun2014, Vol. 111 Issue 3, p291 

    The effects of material ratio, fly ash, and citric acid on the compressive strength and phase composition of magnesium oxysulfate (MOS) cement have been studied. From these results, when the molar ratio of active MgO/MgSO4 increases from 3 to 5, the compressive strength of magnesium oxysulfate...

  • Magnesium oxychloride cement concrete. Misra, A. K.; Mathur, Renu // Bulletin of Materials Science;2007, Vol. 30 Issue 3, p239 

    The scope of magnesium oxychloride (MOC) cement in concrete works has been evaluated. MOC cement concrete compositions of varying strengths having good placing and finishing characteristics were prepared and investigated for their compressive and flexural strengths, E-values, abrasion resistance...

  • Performance of Ground Clay Bricks as Partial Cement Replacement in Grade 30 Concrete. Kartini, K.; Rohaidah, M. N.; Zuraini, Z. A. // World Academy of Science, Engineering & Technology;2012, Issue 68, p362 

    Demolitions of buildings have created a lot of waste and one of it is clay bricks. The waste clay bricks were ground to roughly cement fineness and used to partially replaced cement at 10%, 20% and 30% with w/b ratio of 0.6 and tested at 7, 28, 60, 90 and 120 days. The result shows that the...

  • Mechanical Properties of Concrete Made with High Volume Fly Ash Blended Concrete. Ramesh, Kode Venkata; Murthy, D. S. R.; Usha, A. // International Journal of Applied Engineering Research;2011, Vol. 6 Issue 9, p1141 

    Portland cement concrete is a major construction material worldwide. Unfortunately the production of Portland cement releases large amount of CO2 into atmosphere and because this gas is a major contributor to the green house effect and global warming of, the planned and developed countries are...

  • Compressive Strength Of Ground Waste Seashells In Cement Mortars For Masonry And Plastering. Chin-Peow, Woon; Poi-Ngian, Shek; Tahir, Mahmood Md.; Beng Hong, Ahmad Kueh // Applied Mechanics & Materials;2014, Vol. 727-728, p167 

    For environmental protection and sustainable development, many research studies have been carried out on the utilization of waste materials in construction such as fly ash, mine tailings, slags, construction and demolition waste, wood sawdust, rice husk ash, crumb rubber and etc. In this study,...

  • Effect of Admixtures on the Performance of Recycled Fine Aggregate Cement Mortar. Fuxing Wang; Guozhong Li; Juan Chen // Applied Mechanics & Materials;2014, Issue 548-549, p1663 

    The effect of admixtures on the mechanical properties of recycled fine aggregate cement mortar was studied. The result indicated that compared with blank samples the 28d flexural strength, the compressive strength and osmotic pressure of cement mortar were increased by 15.6%, 35.5%, 41.1%...


    The objective of the present work is to predict the compressive strength, water permeability, chloride penetrability and porosity of concretes containing volcanic scoria as cement replacement after 2, 7, 28, 90 and 180 days curing. Concrete specimens have been produced with three different...

  • Experimental Study on Strength Development Pattern of Magnesium Oxychloride Cement Cured in Chloride Solution. Jian-wei Yang; Jin Pi; Yang Pan; Xin Huang // Advanced Materials Research;2014, Issue 1051, p678 

    Based on different molar ratio of MgO/MgCl2, H2O/MgCl2, magnesium oxychloride cement (MOC) paste was prepared, and soaked in chloride solutions of different concentration. The compressive strength of different age was measured and the component and microstructure of the hydrate was tested by...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics