**1. Introduction**

Concrete is the most widely used construction material worldwide, due to its great mechanical and physical properties, with a demand that grows every year due to the

**Citation:** Landa-Ruiz, L.; Landa-Gómez, A.; Mendoza-Rangel, J.M.; Landa-Sánchez, A.; Ariza-Figueroa, H.; Méndez-Ramírez, C.T.; Santiago-Hurtado, G.; Moreno-Landeros, V.M.; Croche, R.; Baltazar-Zamora, M.A. Physical, Mechanical and Durability Properties of Ecofriendly Ternary Concrete Made with Sugar Cane Bagasse Ash and Silica Fume. *Crystals* **2021**, *11*, 1012. https://doi.org/10.3390/ cryst11091012

Academic Editors: Cesare Signorini, Antonella Sola, Sumit Chakraborty and Valentina Volpini

Received: 12 July 2021 Accepted: 21 August 2021 Published: 24 August 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

need for the development of civil infrastructure across all countries in the world [1–8]. Even though concrete is durable, it is compromised when exposed to aggressive media where chloride and sulfate ions may be present, which are considered to be the main responsible agents for the premature deterioration of reinforced concrete structures, in which the main problem is the corrosion of reinforcing steel [9–14]. This compromises sustainable development by not complying with the useful lifetime for which the structures were designed; additionally, it is known that the manufacture of Portland cement, the main component for the development of concrete, is responsible for around 5 to 8% of total CO2 emissions worldwide [15–17]. This has led the scientific community to look for options to reduce the environmental impact due to the use of concrete, of which the addition of supplementary materials to Portland cement is a very favorable option. These materials are industrial wastes, of which Fly ash is a waste material in the power generation industry, and reusing this highly active pozzolan in the construction industry may bring about several advantages [18]; silica fume (SF) is a byproduct from the production of silicon alloys such as ferro-chromium, ferro-manganese, calcium silicon, etc., which also creates environmental pollution and health hazards [19]; blast furnace slag is a waste product of the steel manufacturing process [20]; and among agro-industrial wastes, the most used as alternative materials to Portland cement are rice husk ash [21] and sugar cane bagasse ash (SCBA) [22–24].

Lua et al. found that fly ash (FA) and blast furnace slag (BFS) with various contents (cement replacement ratio at 0, 20, and 40%) significantly affected the autogenous selfhealing ability of early age cracks. The self-healing efficiency of early age cracks decreased with increases in FA and BFS content. BFS mortars exhibited greater recovery in relation to water penetration resistance compared to the reference and FA mortars [25]. Likewise, Anandan et al. determined that the mechanical properties of processed fly ash based concrete with 50% OPC replacement had equal or better strength gain at later ages than unprocessed fly ash based concrete with 25% OPC replacement [26], and in another research work it was shown that binary concretes with 20% fly ash reinforced with AISI 304 Steel presented a higher corrosion resistance than AISI 1018 steel when exposed to a simulated marine environment [27].

Atis et al. showed that the compressive strength of silica fume concrete cured at 65% RH was easier to influence than that of Portland cement concrete. It was found that the compressive strength of silica fume concrete cured at 65% RH was, on average, 13% lower than silica fume concrete cured at 100% RH in concretes with three different water/cement ratios and SF percentages of 10, 15 and 20% [28]. Bhanja et al., based on findings of compressive and tensile strength increases with silica fume incorporation, determined that the optimum replacement percentage is not a constant one but depends on the water–cementitious material (w/cm) ratio of the mix [29]. Ozcan et al. concluded that inclusion of silica fume in concrete increased the compressive strength between 20% and 50% compared to control PC concrete and there was an optimum replacement ratio of silica fume, which could be predicted using artificial neural networks (ANN) and fuzzy logic (FL) [30]. Landa et al. determined that sustainable binary concretes made with 10% SF provided high corrosion resistance to AISI 1018 steel when exposed to sulfates for more than 300 days [31].

Fly ash, silica fume and SCBA have been used in various investigations as supplementary materials to cement with excellent results, such as from Srinivasan et al. who in their studies showed that SCBA in blended concrete had significantly higher compressive strength, tensile strength, and flexural strength compared to concrete without SCBA. It was found that the cement could be advantageously replaced with SCBA up to a maximum limit of 10% [32]. Another study showed that green concretes with substitution of 20% of Portland cement for with SCBA presented a great resistance to corrosion when reinforced with stainless steel [33]. Kawade et al. obtained results showing that SCBA concrete had significantly higher compressive strength compared to concrete without SCBA. The optimal level of SCBA content was achieved with 15.0% replacement and the partial replacement of cement by SCBA increased workability of fresh concrete; therefore, use of super plasticizer was not essential [34]. Castaldelli et al. evaluated different BFS/SCBA mixtures, replacing part of the BFS with SCBA from 0 to 40% by weight; the results of the mechanical resistance values were approximately 60 MPa of compressive strength for BFS/SCBA systems after 270 days of curing at 20 ◦C. This demonstrated that sugar cane bagasse ash is an interesting source for preparing alkali-activated binders [35]. There are several studies of sustainable concretes, including SCBA, that have shown that corrosion resistance increased compared to that of reinforcing steel when exposed to sulfated media or marine media [22,36–39], and some research has also been reported on the use of SCBA for green road construction [40,41].

Despite the fact that a large number of studies have been carried out worldwide on the benefits of the inclusion of SCBA for the preparation of concretes and mortars, there is still no standardized process for its commercial use as there is for fly ash and silica fume.

When using alternative materials to Portland cement, there are three very important impacts on development in the construction field. The first is the improvement in physical, mechanical and durability properties of the concretes. The second is the reduction in CO2 emissions when making concrete to build civil infrastructure (bridges, houses, dams, hospitals, roads) by reducing the amount of Portland cement per cubic meter of concrete. The decrease is proportional to the amount in which the Pozzolanic material replaces Portland cement, so that the more volume of Portland cement is replaced, the greater the impact on the environment will be, in accordance with the findings of Dong et al.: when 50% of the cement content was replaced by FA, the embodied CO2 emissions for the UHPC mixture were reduced by approximately 50% as compared to the CO2 emissions calculated from conventional normal-strength concrete [42]. The third is the impact on the culture of recycling waste materials. In first-world countries, the use of fly ash and silica fume is already significant compared to emerging countries, such as Mexico, where at the moment there does not exist civil infrastructure where concrete has been used with replacement in large volumes by this type of material.

Therefore, in this research work, physical, mechanical and durability tests were carried out on Ecological Ternary Concretes (ETC), made with substitution of Portland cement in 10, 20, 30, 40 and 50% of combinations of SCBA and SF, in order to determine the most suitable substitution percentage for the fabrication of ETC that provides better performance than a conventional mixture. Six concrete mixes were produced with a water–cement ratio of 0.65. The physical properties of the concrete in the fresh state, such as slump, volumetric weight, and temperature, were determined according to ASTM and ONNCCE standards. For the mechanical properties, compressive strength tests were carried out as well as rebound number tests, and for the durability parameter of all the study mixtures, the electrical resistivity was determined.

#### **2. Materials and Methods**

#### *2.1. Materials*

For the elaboration of the study specimens, Portland cement type CPC 30R was used according to the NMX-C-414-ONNCCE standard [43], sugar cane bagasse ash (SCBA) was obtained from a sugar mill located in the town of Mahuixtlán, Veracruz, México, and silica fume (SF) was acquired commercially. Six concrete mixtures were made for the present research, the first of conventional concrete, denoted the control mix (MC), and the remaining five of Ecofriendly Ternary Concrete (ETC), made by substituting the CPC 30R for combinations of SCBA and SF at percentages of 10, 20, 30, 40 and 50%. SCBA and SF were used because they are agro-industrial and industrial wastes with pozzolanic properties due to their chemical composition. The results of the chemical characterization of the cementitious materials used, obtained by X-ray fluorescence (XRF) analysis, are presented in Table 1.


**Table 1.** Chemical composition of the cementitious materials obtained by XRF.

The coarse and fine aggregates used for the preparation of the study mixtures were from banks of the Xalapa region. Table 2 summarizes the physical characteristics of the materials used; the tests were carried out according to ASTM standards [44–47].


#### *2.2. Proportioning of the Mixtures MC and ETC*

Fine (Sand) 2.60 1764 1.56 3.40 -

For the design and proportioning of the concrete mixtures, the ACI 211.1 method [48] was used; a water/cement ratio = 0.65 and a slump of 10 cm were measured for all concrete mixes. Table 3 presents the dosing of the six studied mixtures, the control mix (MC) and the five Ecofriendly Ternary Concrete (ETC) mixtures made with substitution of CPC 30 with combinations of SCBA-SF at 10, 20, 30, 40 and 50% (ETC-10, ETC-20, ETC-30, ETC-40, ETC-50).

**Table 3.** Dosage of ternary concrete mixtures (Kg/m3).

