The study of the microstructure of sustainable composite cement-based mortars

Abstract

A signifi cant attention is drawn by researchers in recent years towards cements with partial replacements of supplementary cementitious materials [SCM], to reduce the adverse effect of global warming. The research presented in this paper involves the microstructure study of composite cement [CC] which falls into the category of ternary blended cements, consisting of ordinary Portland cement [OPC] and SCMs: Fly Ash [FA] and Granulated Blast Furnace Slag [GBFS], as partial replacement of OPC. The proportion of OPC, FA, and GBFS considered are 45%, 22%, and 33% respectively which is in accordance with IS 16415: 2015. The effi cacy of using the CC effectively in construction practice needs the understanding of the behaviour and phase transforma-tions occurring during the process of hydration, which affects the strength and performance of mortars. This study examines the phase changes at different curing periods viz. 3,7,14,21,28,56 and 90 days, along with the strength of OPC and CC mortars as well as the microstructure investigation. As it was expected, the initial rate of strength gain of CC is lower, compared to OPC, due to the slow development of pozzolanic activity. The strength gain of OPC has practically obtained its class at 28 days but in CC it has continued till 90 days. The ultimate strengths of both the cements are quite comparable at the end of 90 days.

The infl uence of cement on the environmental performance of construction products on the example of cementitious adhesives – External Thermal Insulation Composite Systems [ETICS] components

“…Podczas produkcji cementu CO 2 powstaje w reakcji chemicznej zachodzącej podczas wypału klinkieru [rozkład węglanów] oraz spalania paliw kopalnych niezbędnych do uzyskania odpowiednich temperatur procesu (40). Od lat przemysł cementowy obniża ślad węglowy cementu poprzez rożne działania, jak zmiany składu fazowego klinkieru, w tym stosując surowce zawierające związki wapnia inne niż węglanowe (41), produkcję cementów z nie-klinkierowymi składnikami głównymi będącymi ubocznymi produktami przemysłowymi (42)(43)(44) oraz wykorzystując paliwa alternatywne (45). W 2020 roku stosunek klinkieru do cementu na świecie wynosił 0,72 i winien zmniejszyć się do 0,65 przed 2030 rokiem, aby osiągnąć zerową emisję netto gazów cieplarnianych w 2050 roku (38).…”

“…Z tego względu dostarczenie jak największej ilości rzeczywistych danych z zakresu oddziaływania środowiskowego wytworzenia różnych dóbr, w tym materiałów budowlanych jest ważne, i to nie tylko w związku ze stale by a chemical reaction that takes place during the burning of clinker [decomposition of carbonates] and the combustion of fossil fuels necessary to obtain the appropriate process temperatures (40). For years, the cement industry has been reducing the carbon footprint of cement through various activities, such as changing the phase composition of clinker, including the use of raw materials containing non-carbonate calcium compounds (41), the production of cement with non-clinker core components that are industrial by-products (42)(43)(44), and the use of alternative fuels (45). In 2020, the clinker--to-cement ratio in the world was 0.72 and should decrease to 0.65 by 2030 to achieve net-zero greenhouse gas emissions by 2050 (38).…”