Strength and deformation characteristics of high-strength self-sealing lightweight concretes on artificial and natural porous fillers

Introduction. The results of studies of high-strength self-compacting lightweight concretes based on a Portland cement binder with an organo-mineral modifier of the MB type and three different types of light aggregates (sand and gravel/crushed stone) are presented, the results of which can be used to calculate and design light-weight reinforced concrete structures of buildings, as well as to make changes and expand the boundaries of the parametric range of light concrete from B40 to B70 in SP 63.13330.2018. Aim. Assessment of the influence of technological factors on the strength and deformation characteristics of high-strength self-sealing lightweight concrete of classes B40–B70 grades of medium density D1600–D2000 from self-sealing mixtures. Materials and methods. For the preparation of high-strength self-sealing lightweight concretes, materials were used: Portland cement CEM I 42,5; organo-mineral modifier MB10–50C; micro filler – ground limestone; natural quartz sand; light porous aggregates – artificial expanded clay sand and gravel and natural tuff sand and crushed stone from two deposits. The tests of concrete mixtures and concretes were carried out using standardized and special techniques. Results. The strength (cubic and prismatic compressive strength) and deformation (initial modulus of elasticity, Poisson's ratio and maximum relative compression deformations) characteristics are determined and stress diagrams (σ – ɛ) of six high-strength self-sealing lightweight concretes of compressive strength classes from B41 to B73 with an average density grade from D1600 to D2000 are constructed. The impact of cement consumption, the type of light porous aggregates (sand and gravel/crushed stone) and the replacement of light expanded clay sand with natural sand from dense rocks on the physical and technical characteristics of light concrete has been assessed. Conclusions. The use of various types of light porous aggregates of artificial (ex-panded clay sand and gravel) and natural (tuff sand and crushed stone) origin, as well as fine aggregate from dense rocks (natural quartz sand), together with a Portland cement binder with the addition of an organo-mineral modifier of the MB type, makes it possible to obtain high-strength self-sealing lightweight concretes of grades B40–B70 according to medium density D1600–D2000 with strength and deformation characteristics, significantly exceeding the maximum normative values for lightweight concrete of class B40 grade with an average density of D2000 according to SP 63.13330.2018.