Properties of Natural Hydraulic Lime Prepared from Calcite Tailings

Considering CO2 emissions during production and re-mineralization during hardening, natural hydraulic lime (NHL) has been deemed an ideal cementitious material based on CO2 cycling. However, the preparation of NHL has rarely been reported. In this study, NHL clinker was prepared by calcining calcite tailings, and NHL was obtained by digesting the clinker. The results showed that the performance of the prepared NHL when calcining the calcite tailings at 1,200 degrees C for 1 h and digesting the clinker at 20 degrees C 1 2 degrees C and 70% 1 5% RH (relative humidity) for 8 days met the requirements of NHL5 standard lime mortar. Furthermore, carbonation of the prepared NHL5 was studied, showing that the pore size of the hardened NHL5 mortar was refined during carbonation, and its compressive strength also improved. The prepared NHL5 could be an environmentally friendly cementitious material owing to its utilization of waste, relatively lower energy consumption, and higher CO2 recycling rate. DOI: 10.1061/(ASCE)MT.1943-5533.0004580. (c) 2022 American Society of Civil Engineers.

Automated summary

In this study, natural hydraulic lime (NHL) was prepared by calcining calcite tailings and digesting the clinker. The prepared NHL met the requirements of NHL5 standard lime mortar. Carbonation of the prepared NHL5 refined the pore size and improved the compressive strength of the hardened mortar. The prepared NHL5 could be considered as an environmentally friendly cementitious material due to its utilization of waste, lower energy consumption, and higher CO2 recycling rate.