Abstract
The ornamental stone industry generates large amounts of waste thus creating environmental and human health hazards. Thus, pastes with 0–30 wt.% ornamental stone waste (OSW) incorporated into ordinary Portland cement (OPC) were produced and their rheological properties, hydration kinetics, and mechanical properties were evaluated. The CO2 equivalent emissions related to the pastes production were estimated for each composition. The results showed that the paste with 10 wt.% of OSW exhibited similar yield stress compared to the plain OPC paste, while pastes with 20 and 30 wt.% displayed reduced yield stresses up to 15%. OSW slightly enhanced the hydration kinetics compared to plain OPC, increasing the main heat flow peak and 90-h cumulative heat values. The incorporation of OSW reduced the 1-, 3-, and 28-days compressive strength of the pastes. Water absorption results agreed with the 28 days compressive strength results, indicating that OSW increased the volume of permeable voids. Finally, OSW incorporation progressively reduced the CO2 emission per m3 of OPC paste, reaching a 31% reduction for the highest 30 wt.% OSW content. Overall, incorporating up to 10 wt.% with OSW led to pastes with comparable fresh and hardened properties as comported to plain OPC paste.
Highlights
Sandstone composed mainly of quartz is commonly extracted as an ornamental plate
At 1 day, all ornamental sandstone waste (OSW) mixtures presented CO2-eq intensity higher than REF. This is due to the negative effects of OSW on the compressive strength at this age, despite the contribution of OSW towards CO2 emissions
Due to pastes lower compressive strength, the incorporation of OSW increased the cement intensity index compared to REF at this age (Figure 10)
Summary
Sandstone composed mainly of quartz is commonly extracted as an ornamental plate. Its use as a building material generates significant ornamental sandstone waste (OSW) in the quarries [1,2]. The current study investigates the incorporation of a specific OSW from southern Brazil in cementitious materials It is well-known that the cement industry has significant environmental impacts since its production involves high energy consumption and carbon dioxide (CO2) emissions. The present work addresses the following points (i) reduction of environmental hazards by using waste material in the construction sector and (ii) production of sustainable cement pastes by reducing the OPC consumption and, the CO2 emissions. It aims to investigate the effect of replacing OPC by 10, 20, and 30 wt.% OSW on the paste’s rheological properties, hydration kinetics, and mechanical behavior. It will evaluate the CO2 equivalent emissions related to pastes production
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