DEFINING THE OPTIMUM RATIO OF THE MAGNESIA CEMENT MIXTURE COMPONENTS: SEALER
Problem statement. Visualizing the mechanical strength of both pure magnesia stone and aggregate stone with different component ratios provides a three-component diagram. The finishing laboratory of the Academy of Construction and Architecture [1] studied the dependence of strength on the ratio of MgO to MgCl2 solution of different concentrations. The strength Rcompr..28 increases with increasing the solution density and the ratio of MgO content to MgCl2 solution from 0,5 to 1,6. S. I. Kilesso [6] obtained similar results by mixing magnesia cement with magnesium sulphate solution. Purpose. Defining the optimum ratio of magnesia cement mixture components: sealer and comparing magnesia stone structures, formed by the interaction of magnesia cement and bishofit of different density, but with same newgrowths. Conclusion. The developed composition based on magnesite fired (calcined) at 970°C in a SSHOL typeelectric furnace and high concentration MgCl2 solution ( ρ = 1,28 g/sm3) can be used as a matrix for manufacturing construction products for different applications. The increase of MgCl2 solution density from ρ = 1,18 g/sm3 to ρ =1,28 g/cm3 increases the rate of the mixture hydration by 10-20 % (Table. 3). By increasing the sealer density to ρ = 1,28 g/sm3, we reduce the percentage in Mg(OH)2 stone from 5 to 8 times, i. e. from 32 % to 4 % (at 28 days), within different curing times (Table. 4). By using quantitative X-ray phase analysis it has been determined, that with increasing bishofit density up to 1,28 g/sm3 there is formed 5MgО·MgCl2·13H2О in the stone from 1,68 to 2,5 times more, and 3MgО·MgCl2·11H2О from 3,85 to 13 times more than in the structure formed with cement and bishofit with ρ = 1,18 g/sm3 (Table. 3). In a non-reacted residue forsterite makes up ≈13 %, and the rest is MgO, but by 28 days of curing of the cement and bishofit mixture with ρ = 1,28 g/sm3, it has been established, that hardly any magnesium oxide remains, therefore there haven't even been any hairline cracks found on the pats unlike the cement and bishofit stone sample with ρ =1,18 g/sm3, where some through cracks have been observed. In the magnesia stone structure formed with cement and bishofit with ρ = 1,28 g/sm3 by 28 days of curing approximately twice more pentoxyhydrochloride, and over 10 times more trioxyhydrochloride crystallize, as compared to the cement and stone bishofit stone structure with ρ = 1, 18 g/cm3, which results in the difference of the strength values (Table. 4), though not proportionally. Waterproofing value of both structures is less than the standard value (≤ 0,8), consequently, in order to increase Кр (Si) content, furthermore we have to add special modifiers in the mixture composition of cement and MgCl2 solution with ρ =1,28 g/sm3 (Table. 5).