Sustainable Alternative for the Production of Soil Cement Bricks

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With the prospect of growth in civil construction, it is estimated that the consumption of materials will increase, with a direct impact on the need for inputs to meet such demand. The National Construction Cost Index -M (INCC-M) changed 1.24% in July 2021, accumulating a variation in the last 12 months of 29.03%. Among these, masonry stands out, which represents a significant percentage in constructions (approximately 4% to 12%) total budget (Mattos, 2019).
Most masonry constructions are made with conventional ceramic bricks, which, despite their low cost, require large amounts of mortar for laying, roughening, and plaster, thus increasing the cost per square meter (Mattos, 2019).
Since the beginning of the Industrial Revolution, an increase in the generation of waste from industrial production and consumption of natural resources has been observed. However, only in the last decades has society become aware of the impact caused to the environment by these actions (Marques, Santos, Cruz, & Torres, 2021).
The problem of the generation of Construction and Demolition Waste (CDW) involves its disposal, a process in which irregularities are frequently observed. Unfortunately, as a consequence, negative impacts on urban centers are commonly observed. Paz, Lafayette and Sobral (2020) mapped and evaluated 857 illegal dumping sites in the Metropolitan Region of Recife/Brazil, analyzing 7 municipalities and identifying the types of waste improperly deposited (Paz, Lafayette, &. Sobral, 2020). Therefore, the present work aimed to evaluate the physical, mechanical and chemical performance of soil-cement composites and residues from marble and civil construction for the production of soil-cement bricks.
The present work had, as general objective, the evaluation of the viability of the incorporation of residue in the production of soil cement bricks, seeking eco-efficient alternatives for the applicability and inclusion of composites from marble and civil construction.

Solid Waste: Definitions and Legislation
Insufficient management, associated with a set of other factors, becomes one of the most significant problems faced by the environmental sector (Aguiar, Ribeiro, Viana, & Pontes, 2021). Since the lack of control over urban growth has been perceived, discussions and debates related to solid waste management have become increasingly common. This disorderly growth has resulted in actions promoted by governmental and non-governmental entities that aim to reduce problems related to the theme. This, in turn, has been possible through the implementation of norms and legislation that regulate the sector's guidelines (Silva, Santos, & Araújo, 2017).
Resolution No. 307 of the National Environment Council classifies waste into 4 classes (A, B, C and D) constituting the guideline for applying the 3Rs (reduction, reuse and recycling), in addition to describing the attributions and responsibilities on who generates and who is responsible for each waste (MMA, 2002).
A publication of the Global Waste Index discussed the assessment of 38 countries in relation to the generation of waste. Firstly, South Korea stood out, with 400kg of waste generated, 243kg/inhabitant recycled, 88kg/inhabitant incinerated, and 46kg/inhabitant disposed of in landfills. Peru ranked last, with 424 kg/inhab of waste generated, 47 kg/inhab recycled, 0 kg/inhab incinerated, 347 kg/inhab disposed in landfills and 176 kg/inhab dumped openly (TER, 2022).
With practices that divide its municipal waste into landfills, recyclables, composting and incineration, South Korea is known as a zero-waste country, where the disposal of food waste is also charged depending on the weight produced by each municipality, discouraging further waste in the country. By 2022, the South Korean government plans to halve the amount of single-use plastic used in the country and increase recycling by 70% (TER, 2022).

Marble Waste (MW)
Marbling waste (MW) is also known as ornamental stone cutting waste, which can be classified as to its origin, between natural and artificial, being the processing of marble and granite of natural origin and silestone, marmoglass and others of artificial origin (Figure 1, Santos, 2020 characteristics can hinder the process of demolding the brick as soon as it leaves the press, and also emphasizes that high plastic shrinkage can occur during drying. Soil correction was carried out with washed sand with a coarser granulometric portion, approaching its production soil to the requirements of NBR 10833 (ABNT, 2012) in 70% of sandy soil.
Regarding the production of soil cement bricks following the guidelines of NBR 10833 (ABNT, 2012), it is also noteworthy that all composites met the criteria of that standard, and only the CDW residue did not meet the minimum required, which is 10 at 50% passing through the 0.075mm sieve, with a result of 9%. N. Dantas (2020) used the coarse sandy characteristic of CDW to correct the soil with clayey characteristics used in his study. The chosen CDW had 67.83% sand, 11.5% clay and 20.65% silt.
For Barreto (2020), MW should be added in smaller amounts to evaluate the possibility of contribution as a filler, with the objective of filling the voids of the mixture in the cement soil. Besides this, the author also cites the example of the use of filler in Portland Cement composite CP II-F.
The tests to obtain the specific weight of particles related to soil, waste and their mixtures are shown in Table 2.
Of the values obtained, the soil that presented density of 2.64 g/cm³ stands out, representing 3% more than the composite MW30%CDW70%. The MW100% composite had a density of 2.65 g/cm³, while the CDW had 2.66 g/cm³.  Barreto (2020) found a value of 2.54 for CDW, while for MW the value was 2.66. This value can be justified according to the minerals present in the material, in which the presence of crystalline phases of Quartz and Calcite was identified. The Atterberg limits indicate samples of weak and medium plasticity, as shown in Table 3. It was possible to observe that the MW15%, MW100% and MW30%CDW70% composites were classified as weakly plastic. In the case of MW15%, the value of the Plasticity Index approached the threshold that defines the state as weakly plastic and moderately plastic with a PI of 7, while soil and composites with intermediate additions MW25% and MW50% were classified as moderately plastic.
Only for CDW it was not possible to perform the classification of consistency because it did not present sufficient characteristics to perform the test, being considered as non-plastic and non-liquid. Nascimento (2018) in his study also classified CDW as non-liquid (NL) and non-plastic (NP).

Mechanical Characterization
The compaction tests performed with information related to the addition of binders and/or without the addition jms.ccsenet of lime an content (h with the incorp moisture conten paction curves and 7 it is poss J well as the re nted in Table 4 arent specific w ut binders For the plasticity characteristic of soil and composites, they ranged from weakly plastic to moderately plastic, except for the CDW considered non-plastic non-liquid. The composites MW15%, MW100% and MW30%CDW70% were classified as weakly plastic and the others were considered moderately plastic. In addition to the classification by its plasticity, requirements necessary for the production of bricks were also evaluated, with the information of the plasticity index, only the composite RCMG100% did not meet with a percentage of 1% of PI.
The mechanical behavior of the soil and composites was obtained through compaction tests and simple compression of the specimens, and the characteristics obtained in the compaction test highlighted that the composites presented increasing values in terms of optimal moisture as the percentage of fines in the MW were added. In addition, the optimal moisture value using binders with greater relevance was 21.30% for the MW100% composite.
The simple compressive strength performed on the composites showed results that prove the feasibility of incorporating waste, especially the MW25% composite that obtained the most significant result with 13,777 kPa at 28 days of age. Furthermore, all results were considered satisfactory, since the minimum reached at 7 days of age was 3,843 kPa for the composite MW30%CDW70%.
The results obtained in the present work indicate the technical and economic feasibility of using recycled waste from construction and demolition, as well as waste from cuts of marble and granite in the incorporation for the production of ecological bricks, indicating a sustainable alternative for civil construction.
Future studies should be developed in order to improve the percentages of waste addition in the production of ecological bricks, in addition to evaluating possible reductions in environmental impacts in the process produced and in construction.