MODIFICATION OF CEMENT BY FEW-LAYER GRAPHENE

Improving the performance characteristics of concrete and, above all, the compression and bending strength is a very urgent task. This problem is usually solved by modifying concrete with various organic and inorganic products of the chemical industry. In the last decade, nanomaterials, including carbon nanomaterials, are actively used as modifiers. Few-layer graphene and graphene oxide are the most promising modifiers. Few-layer graphene can be produced on an industrial scale using the liquid-phase shear exfoliation of crystalline graphite. This technology is fundamentally different from that of producing few-layer graphene from graphite oxide since it does not use strong acids and ultrasound processing, which reduces the cost of the finished product by ten folds. The paper presents the results of the study of the process of modifying cement mixtures with the few-layer graphene produced by the liquid-phase shearing exfoliation of graphite. The modification was carried out by using slurry as mixing water with the few-layer graphene concentrations of 0.02 to 0.07 % relative to cement. To determine the strength characteristics of cement, 40×40×160 mm sample beams were made. Cement solutions and samples were prepared in full compliance with the Standards. The samples were tested for compression and three-point bending. It was experimentally established that the maximum relative strength is achieved at the 0.05–0.06 wt. % concentration (relative to cement) of few-layer graphene, and the further increase in concentration does not lead to the increase in strength. In particular, the compressive strength increases 1.7–2.5 times, when the bending strength increases 1.2–1.5 times. It should be particularly noted that as the compressive strength of a control sample (not modified with the few-layer graphene) increases, the modification effectiveness decreases.