Application of recycled construction waste in the production of concrete products for transport infrastructure facilities

Abstract

The annual volume of construction and demolition waste in Russia remains at the level of 78-97 million tonnes with a recovery rate below 13%, and the principal barrier to the use of concrete rubble in products with regulated properties lies in technical regulation: GOST 32495-2013 assigns crushed concrete aggregate of group I to concretes of strength class B22.5 and below, GOST 26633-2015 limits the water absorption of coarse aggregate for concretes of frost resistance grade F200 and above to 1,0%, and the actual water absorption of recycled aggregate exceeds this limit five- to sixfold. The purpose of the study is to establish the ultimate replacement ratio of natural crushed stone by recycled aggregate with respect to the regulated indicators of small-size products for transport infrastructure and to assess the cost consequences of such replacement. The author's design model combines the absolute volume method, the Bolomey-Skramtaev relationship with a variable aggregate quality coefficient and degradation functions of water absorption, abrasion and frost resistance; the calculation covers six series and three equal-strength compensating compositions at producer prices for April-May 2026. The ultimate replacement ratio amounts to 0.62 for paving slabs of group B governed by abrasion, 0,76 for groups A and B governed by frost resistance, and 0,71 for curb stones governed by flexural tensile strength. Restoring the initial strength at a replacement ratio of 0,50 requires an 11,6% increase in cement consumption. The economic outcome changes its sign with the haulage distance: at producer prices the equal-strength composition is 2,9% more expensive than the reference one, and at delivered prices it is 3,9% cheaper. The governing characteristics are the surface and pore properties of concrete, which implies that the application field of recycled crushed stone is extended by adjusting the regulated indicators of wear and frost resistance while retaining the existing strength classes.