Composite building material containing wood chemistry waste

Abstract

The objective of this study is to develop a technology for manufacturing concretes and their formulations using hydrolysed lignin to improve their quality characteristics (compressive strength, water repellency, frost resistance). To achieve this goal, the following tasks should be solved: to study the chemical composition of hydrolysed lignin; to reveal the influence of mechanochemical activation on the structure of hydrolysed lignin; to select optimal conditions for obtaining composite building materials; to determine the physical and mechanical properties of the developed composite materials. Portland cement M 400 was used in the experiments; sand was used as a fine aggregate (GOST 8736-2014) with a fineness modulus of 2.2 at a ratio of 1:4 (the expected concrete grade is B35). The water-cement ratio was 0.5. 10% sodium water glass (GOST 13078-81), finely ground hydrolysed as lignin organic filler and carbamide (GOST 2081-92) as organic modifier were used. IR spectroscopy was used to determine the chemical composition of hydrolysed lignin. The study showed that hydrolysed lignin is an active organic additive. The polar groups (hydroxyl, carbonyl, carboxyl) in its molecule are capable of strong intermolecular interaction and can facilitate its association in solutions, leading to possible chain cross-linking reactions, condensation reactions, both in acidic and alkaline media. To obtain high-quality construction composite materials with desired properties, the following raw mixture comprising Portland cement, sand and additional components is recommended: 30–50% of hydrolysed lignin and 20–40% of carbamide of the mixture mass.