Resistance to Chemical Attack of Hybrid Fly Ash-Based Alkali-Activated Concretes

Abstract

The environmental impacts related to Portland cement production in terms of energy consumption, the massive use of natural resources and CO2 emissions have led to the search for alternative cementitious materials. Among these materials, alkali-activated cements based on fly ash (FA) have been considered for concrete production with greater sustainability. In the present article, the chemical durability properties (resistance to sulphates, chloride permeability, and resistance to carbonation) of a hybrid alkali-activated concrete based on fly ash–ordinary Portland cement (FA/OPC) with proportions of 80%/20% were evaluated. It is noted that the FA was a low-quality pozzolan with a high unburned carbon content (20.67%). The results indicated that FA/OPC concrete had good durability with respect to the OPC concrete, with 95% less expansion in the presence of sodium sulphate and a 2% strength loss at 1100 days, compared with the 56% strength loss of the OPC concrete. In addition, FA/OPC showed lower chloride permeability. On the contrary, the FA/OPC was more susceptible to carbonation. However, the residual compressive strength was 23 MPa at 360 days of CO2 exposure. Based on the results, FA/OPC, using this type of FA, can be used as a replacement for OPC in the presence of these aggressive agents in the service environment.

Portland Versus Alkaline Cement: Continuity or Clean Break: “A Key Decision for Global Sustainability”

“…Industrially produced hybrid H-Cement, is characterized by ready grindability, to a specific surface of 6,100 cm 2 /g, an output of 22 t/h and an energy consumption of 63 kWh/t, compared to an output of 12 t/h and energy consumption of 115 kWh/t for conventional CEM I 52.5 R cement with a specific surface of 5,100 cm2/g produced in the same facility (Martauz et al, 2016). In recent years, much information has been published on the hydration mechanisms in hybrid cements (such a H-cement) and their physical and mechanical properties, along with their durability (Garcia-Lodeiro et al, 2018;Fernández-Jiménez et al, 2019b;Askarian, et al, 2018;Valencia-Saavedra and de Gutiérrez, 2020;Xue et al, 2021).…”

“…In recent years, much information has been published on the hydration mechanisms in hybrid cements (such a H-cement) and their physical and mechanical properties, along with their durability ( Garcia-Lodeiro et al, 2018 ; Fernández-Jiménez et al, 2019b ; Askarian, et al, 2018 ; Valencia-Saavedra and de Gutiérrez, 2020 ; Xue et al, 2021 ).…”

The Capacity of Alkali‐Activated Industrial Wastes in Novel Sustainable Ceramic Membranes

“…The durability against the sulfate attack is also dependent on the cation in the solution. Alencia-Saavedra et al reported that the alkaliactivated FA/OPC sample was more durable in Na 2 SO 4 solution than MgSO 4 solution [99].…”

Evaluating the compressive strength of glass powder-based cement mortar subjected to the acidic environment using testing and modeling approaches

“…Since the attack of H 2 SO 4 is coupled with sulfate, it is one of the most harmful acids for cement-based materials [ 17 ]. Sulfate attack is a prominent component in the deterioration of cement-based materials and affects their durability because of the chemical assault by sulfates and the physical attack owing to salt crystallization [ 18 , 19 ]. The breakdown of CSH leads to the formation of additional compounds, which contribute to the durability issues of cement-based materials [ 18 ].…”

“…Sulfate attack is a prominent component in the deterioration of cement-based materials and affects their durability because of the chemical assault by sulfates and the physical attack owing to salt crystallization [ 18 , 19 ]. The breakdown of CSH leads to the formation of additional compounds, which contribute to the durability issues of cement-based materials [ 18 ]. Hence, it is important to study how acid attacks could shorten the lifespan of cement-based materials.…”