The dissertation is devoted to solving the problem of obtaining composite systems using thermally activated waste of paper production for road construction and establishing the features of the formation of a complex of physical, mechanical and operational properties of cement road concretes and reinforced soils with improved properties.
The physicochemical and hydraulic properties of thermally activated waste (TAW) were studied. It was shown that during their heat treatment, processes characteristic of carbonate-clay raw materials occur with the formation of β-C2S, С12А7, С3А, С2АS. It was established that the hydration of TWA is characterized by active interaction with water, which is accompanied by significant heat release and rapid hardening. It was shown that a necessary condition for the hydration hardening of thermally activated waste is the regulation of early structure formation processes by using hardening retarders, in particular, additives of 7.0 wt% CaSO4∙2H2O and 1.0 wt. % tartaric acid, the use of which provides increased strength indicators for obtaining the required hardening times, and allows you to obtain regulated thermally activated waste (RTAV). It has been established that the hydrated phase, which provides retardation of hardening and early strength of RTAV, is ettringite. Upon further hardening, calcium hydrosilicates are formed, which densify the structure, contributing to an increase in the strength of the binder.
The compositions of soils reinforced with RTAV have been developed, and their construction and technical properties have been studied. It has been established that the swelling of reinforced soils decreases regardless of the type of binder, while the bearing capacity, determined on the basis of the California CBR coefficient, for reinforced soils compared to unreinforced ones increases with an increase in the content of binders, especially RTAV. As the conducted studies have shown, the use of RTAV in the amount of 14 wt.% instead of 10 wt.% PC promotes the process of directional structure formation, which ensures the strengthening of the subgrade layer and the achievement of high frost resistance and strength indicators with the obtaining of reinforced soil grades M10, M20 and M40.
The properties of composite systems with different ratios of blast furnace granulated slag (BGS) and regulated thermally activated waste were investigated, and the properties of road cement concretes were developed and determined. The effectiveness of using RTAV for activating BGS, which occurs by sulfate and partially alkaline mechanisms, was established. The results of physical and mechanical tests of samples of the composite system "BGS-RTAV" showed that the highest early strength - 2.23 MPa in bending and 7.6 MPa in compression are achieved by samples with the maximum BGS content - 70 wt.%. However, the highest indicators of both compression (38.3 MPa) and bending (4.6 MPa) strength in late hydration, when the hydrosilicate type of hardening prevails, are characterized by samples with a ratio of BGS:RTAV = 70:30. Studies of the phase composition of the developed composite system indicate the formation of hydrosilicates, calcium hydroaluminates, which, interacting with gypsum present in the composition of the RTAV, form calcium hydrosulfoaluminate in the initial period of hydration. The use of 5 wt. % RTAV and 0.8 wt. % superplasticizer Stachement 2570 ensure active kinetics of early strength gain and the highest tensile strength of concrete in bending, which corresponds to the class Btb 6.4, and achieving the class of concrete in terms of compressive strength C 40/50. Rigid concrete mixtures of nominal composition 1:1.9:3.8 with a content of 0.8 wt. % superplasticizer, 0.2 wt. % air-entraining additive Microporan were developed. The influence of RTAV on the strength and energy characteristics of crack resistance of the developed road concretes was investigated. Analysis of the obtained complete state diagrams of concretes indicates a positive effect of adding 5 wt.% of RTAV on the performance of concrete in both the pre-critical and post-critical stages, and are also characterized by the highest static critical stress intensity coefficients. It was established that concretes with the optimal RTAV content are characterized by a frost resistance grade of F300 and abrasion resistance G=0.29 g/cm2.
The results of experimental and industrial testing of composite systems using RTAV of paper production are presented. The developed RTAV were used as binders when arranging the base layers of the road surface at the facility “New construction of the 35/110 kV TPP “Yavorivskaya WPP/SES” in the territory of Yavoriv district of Lviv region. The economic efficiency of using RTAV in road cement concretes is shown. It was established that the expected effect of using RTAV as an additional cementing material is 94 thousand UAH. when constructing 1 km of cement concrete pavement of a category Ⅱ highway.
