Tailoring self-pulverized low-calcium clinker for CO2 sequestration

Abstract

To reduce energy consumption and greenhouse gas emissions in the cement industry, this study develops a novel low-calcium clinker with self-pulverization properties. The clinker is synthesized from limestone and sandstone raw materials and comprises dicalcium silicate (2CaO·SiO2 (C2S)) as the primary mineral and rankinite (3CaO·2SiO2 (C3S2)) as the auxiliary mineral. The influence of calcination temperature, cooling rate, and holding time on clinker pulverization and mineral formation is investigated through a series of experiments. The optimal calcination condition involves heating at 1240 °C for 1 h, followed by natural cooling, resulting in a self-pulverized low-calcium clinker (SPLCC) with main mineral is γ-C2S and contains β-C2S, C3S2, and C2AS (Calcium alumina feldspar (2CaO·Al2O3·SiO2)). The self-pulverized clinker exhibits a pulverization ratio of 93.0 %, a specific surface area of 666.4 m2/kg, and an average particle size of 8.2 μm. Additionally, the clinker displays excellent carbonation reactivity, with the compressive strength reaching 69.3 MPa and 82.2 MPa after 4 h and 24 h of CO2 curing, respectively. The carbonation products are identified as calcite and silica gel. SPLCC can reduce and sequester approximately 277.3 kg of CO2 emissions compared to the hydration of Portland cement clinker when considering the preparation and curing stages. The results highlight the potential of SPLCC as a sustainable cementitious material.