MULTI-CRITERIA OPTIMIZATION OF THE FIBER CONCRETES COMPOSITIONS OF RIGID PAVEMENT

Abstract

The experiment was carried out according to the optimal plan, which four factors of the composition of modified fiber concrete for rigid pavement were varied: amount of Portland cement, polypropylene fiber, metakaolin and polycarboxylate type additive. All concrete mixtures had equal mobility P2. Complex of experimental-statistical models describe the influence of factors on the properties of concrete is obtained. Selection of optimal compositions of fiber concrete of a rigid pavement was carried out using the obtained experimental-statistical models. Graphical optimization method for "squares and squares" diagrams was used. The square in the coordinates "amount of metakaolin" - "amount of complex action additive Coral ExpertSuid-5" was used as a carrier in the construction of diagrams. These values of the mechanical characteristics of concrete were used as limitation criteria: compressive strength at the age of 3 and 28 days, flexural tensile strength, frost-resistance, abrasion. Frost-resistance and abrasion are the main indicators that ensure the durability of concrete for rigid pavement in typical operating conditions. The concrete prime cost indicator was used as an optimization criterion. 2 variants of concretes compositions of classes C30/35 and C32/40 with increased durability and high strength was chosen. The selected compositions of C30/35 class concretes have frost-resistance F350, flexural tensile strength 8.0-8.2 MPa, abrasion 0.38-0.39 g/cm2, compressive strength at 3 days age 35 MPa and strength at 28 days age 54 MPa. The selected compositions of C32/40 class concretes have frost-resistance F400, flexural tensile strength 8.5-8.6 MPa, abrasion 0.34 g/cm2, compressive strength at 3 days age 38-39 MPa and strength at 28 days age 57-58 MPa. All four selected compositions have the amount of metakaolin 15- 20 kg/m3, polypropylene fiber 0.9-1.5 kg/m3, polycarboxylate type additive Coral ExpertSuid-5 0.8- 0.9% of the cement mass.