Low-Carbon Modified Pozzolanic Cement for Concrete of Massive Structures

The possibility of using low-carbon modified sulfate-resistant pozzolanic cement for concretes of massive structures has been shown. It is established that pozzolanic cement CEM IV/B(P-V) 32.5 R-SR produced by PJSC "Ivano-Frankivskcement" provides a sufficiently high standard compressive strength (46.0 MPa) with a lower heat of hydration (254.1 J/g) compared to slag cement CEM III/A (267.7 J/g); in this case the specific carbon dioxide emission is 362 kg/t. The influence of organic-mineral additives of various types on the physical and mechanical characteristics of low-carbon pozzolanic cements and their heat release kinetics has been investigated. Modification of pozzolanic cement with an organo-mineral additive contributes to increasing the flowability of the mortar mixture and increasing the standard strength to 50.0 MPa, while the temperature maximum during the hydration process is shifted by 80 min. Modified pozzolanic cement provides a decrease in the W/C ratio of the concrete mixture and an increase in the compressive strength of concrete at the age of 28 days from 35.1 to 40.7 MPa; at the same time, reduced heat release contributes to limiting temperature gradients and the risk of thermal cracks in the concrete of massive structures. For concrete based on modified pozzolanic cement, the carbon footprint is 123.1 kg CO₂/m³ of concrete, while the CO₂ intensity is 3.0 kg CO₂/(m³·MPa), and the clinker intensity is 3.6 kg clinker/(m³·MPa). It is established that for concrete of class C25/30, the maximum temperature value T=33.9°C is reached 18 h after mixing the mixture. The obtained results confirm the prospects of using modified pozzolanic cement with a low heat of hydration of the CEM IV/B(P-V) type for producing low-carbon concretes of massive structures.