Aqueous Phase of Hydrothermal Liquefaction as a Concrete Modifier

The processes of liquid fuel production from organic wastes by hydrothermal liquefaction lead to the formation of wastewater characterized by a high content of organic compounds, including lignosulfonates and their derivatives. The paper presents the results of a study designed to assess the possibility and feasibility of using such wastewater as concrete modifiers. The study confirmed the hypothesis that the use of HTL-AP slows down concrete curing processes (curing time increased 1.9 times compared to the control sample). It was found that the modifying properties of HTL-AP are higher than those of the commercial concrete modifier because even at higher curing retardation rates (curing time is 12.2% higher compared to concrete modified with the commercial solution), the use of HTL-AP results in minimal reduction in the strength properties of the concrete. The application of HTL-AP and commercial modifier results in a 7.1% and 14.5% reduction in compressive strength, respectively, and a 6.2% and 12.2% reduction in tensile strength, respectively. Based on the results of the study, it is concluded that the use of HTL-AP as a retarder in concrete curing processes is well justified, as the positive effect has been experimentally confirmed. Using HTL-AP as a concrete modifier will improve the environmental efficiency of HTL processes and reduce the cost of frost-resistant concrete by eliminating the use of traditional expensive modifiers.