Abstract
A control of a cement composite structure formation from modern positions should be carried out taking into account the synergistic effect of its components. The goal of the article is to study the combined effect of nanomodified basalt fiber (NBF) and bottom ash (BA) as structural elements of concrete using a two-factor analysis of variance ANOVA. The tasks for achieving this goal are the development of nanomodified basalt fiber bottom ash-cement concretes, as well as the study of their fresh, physical and mechanical properties (slump, slump flow, average density, compressive and flexural strength, elastic modulus and crack resistance) and durability performances (water, frost, and abrasion resistance). Nanomodified basalt-fiber-reinforced concretes (from 0 to 7 wt % NBF) have been developed, in which the economical Portland cement CEM I 32.5 N is replaced by up to 45 wt % mechanically activated bottom ash (400 m2/kg). Achieving uniform flowability of the compositions (slump 20–22 cm and slump flow 45–52 cm) was carried out by varying the dosage of an economical superplasticizer with a high water-reducing ability (35%). The joint effect of the BA and NBF provides control over the structure formation of cement materials, which ensures the redistribution of internal stresses from shrinkage deformations throughout the entire volume of the composite; during loading, the process of crack formation is retarded, stress concentration near structural defects is reduced, and stresses are redistributed in the microstructure of the cement composite between its components.
High values of mechanical properties (compressive strength up to 59.2 MPa, flexural strength up to 17.8 MPa, elastic modulus up to 52.6 GPa, limit stress intensity factor 0.507 MPa m0.5) are explained by the complex effect of bottom ash and nanomodified basalt fibers. For the composition with 30 wt % BA and 5 wt % NBF, W18 water resistance grade, F400 frost resistance grade, and the abrasion resistance of 0.59 g/cm2 were achieved, which characterizes the high durability of the developed materials.