Injection mortars for road pavement subgrade fixing

The object of research is a range of injection mortars (IM) based on composite binders, crushed to S_sp = 500 m²/kg, obtained using CEM I 42.5 N, partially replaced by technogenic resources with the addition of superplasticizer Polyplast PFK-NLM. The purpose of this work is development and comprehensive research of injection mortars for road pavement bases. The tasks for achieving the set purpose are designing the composition of IMs, studying their fresh and physical-mechanical properties, as well as the performances of the fixed bases. Method. The specific surface of bulk raw materials was studied using the PSH-11 device. Several characteristics were assessed for injection mortars: water-cement ratio, workability, water separation, mixture density, compressive strength, elastic modulus, frost resistance. Results. The viscosity of IMs indicates their high penetrating ability, since the flow time of the studied materials through the Marsh viscometer at water-to-binder ratio 0.62 and a water consumption of 140 l/m³ is 33-39 seconds. The start of setting is at least 75 minutes, which allows for effective fixing of road pavement bases. The composite binder contributes to a significant increase in the early compressive strength of IMs (up to 56% compared to the control composition) and flexural strength (up to 75%). The ratio of the flexural and compressive strength of the developed compositions (on 2nd day it is 0.13, on 7th - 0.11, and on the 28th - 0.12) often exceeds a similar characteristic of the control composition, despite the replacement of Portland cement by more than half by wt of wet magnetic separation (WMS) waste from ferruginous quartzites, technogenic fibrous materials (TFM) and SP, indicating the development of crack resistance of the material. An increase in the deformation characteristics of the mixture hardened on CB-50SP+1%TFM was established by 112% compared to the mixture on CEM I 42.5 N cement. Studies of the mixes deformation properties of the allow us to conclude that, based on the developed IMs and crushed stone from metamorphic shale, it is possible to obtain concrete for road pavement bases that meet the regulatory documentation for this type of construction. Tests of samples of reinforced crushed stone bases for the entire range of physical and mechanical properties and performances have shown that the developed IMs compositions allow, when strengthening crushed stone bases, to obtain concrete of class B5 - B10, and they can be used in the construction of pavement bases for high-quality roads.