Assessing the low-carbon potential of magnesium silicate hydrate cement: a probabilistic life cycle approach

Magnesium silicate hydrate cement (MSHC), as an innovative low-carbon cementitious material, is considered a potential substitute for ordinary Portland cement (OPC). However, uncertainties in the carbon emission factors of raw materials and mix proportions pose challenges for assessing its life cycle carbon emissions. This study employs a probabilistic life cycle assessment (PLCA) to evaluate the carbon emission intensity of MSHC and analyze its uncertainties. Leveraging machine learning techniques, a predictive model for the carbon emission intensity of MSHC was developed, and sensitivity analysis was conducted on various characteristic parameters. The results indicate that although MSHC is regarded as a low-carbon material, it does not exhibit low-carbon characteristics in all scenarios compared to OPC. The carbon emission intensity of MSHC is closely related to its mix proportions. Depending on different mix proportions, the average carbon emissions of MSHC range from 0.174 to 1.419 kg CO2e/kg. L-MgO is a key factor influencing the uncertainty of MSHC carbon emissions. Notably, the Mg/Si ratio is a critical factor influencing the carbon emission characteristics of MSHC, with a low-carbon threshold range observed between approximately 0.8 and 1.0.

With the increasing prominence of global warming issues, sustainable development has become one of the core concerns of the construction industry. As a fundamental material in this sector, cement's environmental impact during production cannot be overlooked. silicate hydrate cementitious material (MSHC), as a novel cementitious material, is typically prepared by mixing lightly burned magnesium oxide (L-MgO), siliceous raw materials (SRM), water-reducing agents (WRA), and water. However, although most studies have indicated that MSHC has low-carbon characteristics compared to ordinary Portland cement, quantitative research on carbon emissions from MSHC throughout its entire lifecycle remains. This lack of quantification leaves the scientific basis for MSHC as a low-carbon cementitious material still requiring further validation.

Furthermore, traditional cement lifecycle assessment (LCA) tools face certain limitations during use. They are overly reliant on specific sample data and fail to comprehensively account for data uncertainty caused by factors such as regional differences, production conditions, and product mixing properties. This affects their applicability and reference value in practical applications. Thus, it is necessary to develop a more flexible LCA approach to utilize the extensive existing research results for more accurate simulation and prediction of MSHC’s carbon emission intensity, thereby enhancing its usability.

To address these issues, Professor Li Yue from Beijing University of Technology adopted a probabilistic lifecycle assessment (PLCA) method to quantitatively analyze the carbon emission intensity of MSHC. First, the research objectives and system boundaries of the LCA were defined, and extensive data on carbon emission factors from raw materials and transportation processes were collected to establish optimal distribution models. Then, Monte Carlo simulation was used to quantitatively assess and analyze uncertainties in the carbon emission intensities of 13 typical MSHC mix designs. Based on this, machine learning (ML) techniques were employed to establish a predictive model for MSHC’s carbon emission intensity, with sensitivity analysis conducted on various feature parameters. Additionally, two graphical user interfaces (GUIs) were developed based on the probabilistic LCA method and machine learning model to enable rapid analysis and evaluation of MSHC’s carbon emissions.

Through the aforementioned research and tool development, a more comprehensive understanding of MSHC’s carbon emission characteristics can be achieved. By combining probabilistic lifecycle assessment (PLCA) methods with machine learning techniques, the limitations of traditional cement LCA tools are overcome, providing more precise carbon emission simulations and predictions. This offers reliable scientific evidence for the construction industry in material selection and environmental impact assessment, while promoting the application and development of low-carbon building materials.

This paper “Assessing the low-carbon potential of magnesium silicate hydrate cement: a probabilistic life cycle approach” was published in Smart Construction.

Li Y, Luo X, Liu X, Zhang Z, Meng K, et al. Assessing the low-carbon potential of magnesium silicate hydrate cement: a probabilistic life cycle approach. Smart Constr. 2025(2):0012, https://doi.org/10.55092/sc20250012.