Effect of graphene oxide on the properties of ternary limestone clay cement paste

Abstract

Given the pressing threat of global warming, it is imperative to promote CO2 emission reduction within the cement industry which is widely recognized as a major contributor to the overall carbon footprint. Limestone clay cement (LCC) emerges as a promising alternative to Portland cement. However, to facilitate the implementation of LCC technology, it is urgent to address the low early-age compressive strength issue. Inspired by the successful implementation of nano-engineered cementitious material, we hereby introduce a novel nanomaterial, graphene oxide (GO), into unconventional LCC paste (cement:clay:limestone = 65%:20%:15%, water/binder ratio: 0.45). Experimental results revealed that the 0.09% GO by weight of the LCC binder was the optimal dosage in this work, which improved the compressive strength of the LCC paste at 7, 14, and 28 days by 25.6, 21.6, and 20.3%, respectively. Advanced characterizations were then conducted, suggesting that the admixed GO not only enabled a higher polymerization degree of binder hydrates (which benefited the development of compressive strengths) but also improved the carbonation resistance of LCC paste. These findings not only offer valuable insights for researchers but also provide practical guidance for engineers in the field. Notably, the admixed GO converted the unstable orthorhombic crystal systemic aragonite to the stable trigonal crystal systemic calcite, which offers insights into the technology of carbon sequestration in concrete.