Model-Based Methods to Produce Greener Metakaolin Composite Concrete

Abstract

Metakaolin is reactive and is widely used in the modern concrete industry. This study presents an integrated strength–sustainability evaluation framework, which we employed in the context of metakaolin content in concrete. First, a composite hydration model was employed to calculate reactivity of metakaolin and cement. Furthermore, a hydration-based linear equation was designed to evaluate the compressive strength development of metakaolin composite concrete. The coefficients of the strength evaluation model are constants for different mixtures and ages. Second, the sustainability factors—CO2 emissions, resource consumption, and energy consumption—were determined based on concrete mixtures. Moreover, the sustainability factors normalized for unit strength were obtained based on the ratios of total CO2 emissions, energy consumption, and resource consumption to concrete strength. The results of our analysis showed the following: (1) As the metakaolin content increased, the normalized CO2 emissions and resource consumption decreased, and the normalized energy first decreased and then slightly increased. (2) As the concrete aged from 28 days to three months, the normalized CO2 emissions, resource consumption, and energy consumption decreased. (3) As the water/binder ratio decreased, the normalized CO2 emissions, resource consumption, and energy consumption decreased. Summarily, the proposed integrated strength–sustainability evaluation framework is useful for finding greener metakaolin composite concrete.

The Environmental Profile of Clinker, Cement, and Concrete: A Life Cycle Perspective Study Based on Ecuadorian Data

“…Similarly, these tools quantify the GHG emissions with a focus on the product or service. Park et al [57], in their study of metakaolin composite concrete, use emission factors adapted from Long et al [58] for the calculation of CO 2 emissions, energy, and resource consumption [57,58]. Similarly, authors such as Ghalehnovi et al [59] and Shamsabadi et al [60] use a global warming index derived from Lippiatt [61], based on the GWP of each material and its weight.…”

Mechanical and Physical Performance of Portland Cement Composites with Partial Replacements of Metakaolin and Ulexite

“…Moreover, it was shown that MK replacement in cement could lower the normalized CO2 emissions and resource consumption [14]. MK has to go through a burning process like cement, whereas the temperature of MK production is between 700 °C-900 °C as opposed to 1450 °C in cement production.…”

The Effect of Pozzolanic Waste of Different Nature on the Hydration Products, Structure and Properties of Hardened Cement Paste

“…Metakaolin consists mainly of SiO 2 and Al 2 O 3 and is highly reactive. The pozzolanic reactivity of waste glass and metakaolin strongly influences the kinetics of hydration reaction of the binder and the properties of the obtained specimens [24][25].…”