1.1. Applications of SCB<\/h3>\n\n\n\n
The application of SCB in civil construction has been studied: (i) in addition to cementitious compositions [5<\/a>]; (ii) with cement and SCB ash (the second by-product of this industry, by the SCB burning to produce energy) [6<\/a>]; (iii) in composites of SCB with cement and polymers [7<\/a>]; (iv) in addition to plastic waste [8<\/a>]; (v) in polymeric tiles of hybrid composites of fiber glass and natural fibers from SCB [9<\/a>]. In other industries, such as the automotive, a composite of SCB with recycling PET was studied [10<\/a>] and investigations such as a composite of EPS with SCB [11<\/a>] seek to prospect innovative applications, based on the study of resistance and new physical characteristics of the resulting materials.However, in composites of SCB with earth, as in the studies of Bock-Hyeng et al. [12<\/a>], investigations are scarce and the amount of SCB fiber is very reduced. The present study sought to develop a material capable of responding in a complementary way to the various contemporary demands in a sustainable context. It is intended to rescue ancient technologies, such as adobe, the use of natural fibers, and lime. The innovation in this work is characterized by the use of a relevant amount of SCB fibers, in the order of 30 to 35%, in the studied composites. Moreover, compositions of SCB fibers with lime as the main binder do not seem to exist at this moment. <\/p>\n\n\n\n The proposal for the sugarcane bagasse (SCB) and lime mixtures for building blocks is inspired by the existing similar composite based on hemp and lime, briefly presented below. The composite obtained by replacing lime with soil as a natural binder, such as adobe, but with a greater number of fibers as usual was also studied in the search of a more sustainable solution, as it does not use a large quantity of calcined materials in the formulation. Depending on the characteristics of the materials, in a composite with fibers and soil, it is convenient to add a binder capable of improving resistance to water action. Lime has this advantage because reduces water absorption and favors vapor permeability, forming a limestone barrier around the vegetable fiber [13<\/a>].In the composite without soil in the matrix, lime is capable of adding and maintaining essential properties for the resistance and durability of the material. As a disadvantage, the long carbonation time impacts the curing time, as verified in studies with hemp [13<\/a>].SCB ash has proven a good performance as an efficient pozzolanic material in composites prepared with cement [14<\/a>]. As long as it can improve or preserve the resistance and durability of the material, it is possible that its addition as a pozzolanic material can bring another environmental benefit, namely through the use of a final residue.In this work, three composites with sugarcane bagasse were developed, with a view to making building blocks. These are composites with relevant fiber additions, in the order of 30% to 35% of fibers, in formulations with hydrated aerial lime, with lime and soil, and only with soil. Additionally, the addition of SCB ash was also tested in order to compare the pozzolanic effect of this material with the effect of using metakaolin.The specimens prepared during the study were subjected to laboratory tests with the objective of measuring the mechanical, hygroscopic, and thermal performance of the composites and, thus, verifying the feasibility of applying the product, and also prospecting the potential to act as a structural complement.<\/p>\n\n\n\n The use of hemp fibers in construction goes back a long time. There are hemp\/soil mortars in India that are about 1500 years old [15<\/a>]. The first \u201chemp\/lime concrete\u201d was developed by Charles Rasetti in 1987 in France [16<\/a>]. The woody core, with a high silica content, interacts with the lime and promotes the hardening of the mixture [16<\/a>]. Used for the production of hemp concrete (or hempcrete), the construction material is much studied and used in the European Union.The hemp block walls function as thermal and acoustic insulation and a good compromise between thermal conductivity and thermal inertia [17<\/a>]. The material is easy to adapt to the climate and easy to produce locally. It prevents the occurrence of condensation due to the wall\u2019s breathability and absorption capacity and resistance to water, which impacts the quality of the environment and the health of the inhabitants [16<\/a>].In the life cycle assessment, in addition to being biodegradable, it captures CO2<\/sub> from the atmosphere, reduces the use of toxic materials and waste production, uses renewable resources, and can be recycled at the end of the useful life of the building, thus reducing the environmental impact [13<\/a>,14<\/a>,15<\/a>,16<\/a>]. Its ductility and ability to adjust to building movements prevent the appearance of cracks. It is a non-flammable material, does not release toxic fumes, and is resistant to insects, fungi, and bacteria [17<\/a>]. In addition to the hempcrete research, other agroindustry or agri-food wastes have been studied in lightweight concretes, mainly with lime-based binders and replacing the aggregates in full. For example, the study of Chabannes et al. showed the use of rice husk and hemp as aggregates (without and with previously treated aggregates with Ca(OH)2<\/sub>) using a lime-based binder for lightweight concretes, Lime and Hemp Concrete (LHC), and Lime and Rice husk Concrete (LRC) [18<\/a>]. Chabannes et al. also studied sunflower stem aggregates with eco-friendly binders and their multi-physical properties as insulating concrete [19<\/a>]. However, there are also studies with cementitious binders and only with a partial replacement of aggregates such as the study of Gradinaru et al. with 50% of sunflower aggregates (treated with sodium silicate solution), with 50% of sand and cement as a binder, and with the addition of superplasticizer to reduce the amount of water and obtain greater resistances [20<\/a>]. As no lightweight lime-based concrete study has yet been conducted with total aggregate substitution by sugarcane bagasse, the present study was intended to study simple mixtures, without any treatment of the vegetable aggregate and without additives that change its rheology or its binder adhesion. Only in this way will it be possible to determine the material behavior. In addition, it is also intended to obtain an economically accessible construction product; therefore, a minimum of additions and processes is necessary.<\/p>\n\n\n\n The materials used in the experimental research were sugarcane bagasse (SCB) as an aggregate; aerial lime, SCB ash, Alentejo and Labruge soil, and metakaolin as binders; as an additive, sodium borate or borax.<\/p>\n\n\n\n The SCB used came from Madeira Island, where sugar cane is cultivated for the production of national rum. The preparation of the material used in the mixtures required spreading the wet bagasse over a plastic sheet, where it was turned over twice a week to dry naturally and homogeneously, for 4 weeks, until it was dry. This drying was necessary because, otherwise, fungi would appear, just as it was already appearing in the most humid parts when we received the material. In morphological analysis (Figure 1<\/a>a,b) of SCB samples, it was found that the SCB length varies between 10 and 30 mm, but most are 15 mm. The pieces of SCB are made up of long fibers [21<\/a>] with diameters ranging from 0.2 to 0.5 mm below 100 \u03bcm and scaly surfaces (Figure 1<\/a>c).<\/p>\n\n\n\n Figure 1.<\/strong> (a<\/strong>,b<\/strong>) Dried SCB samples were analyzed under an optical microscope (20\u00d7 magnification) (figures from the authors). (c<\/strong>) Bundle of dried fibers analyzed under the microscope (adapted from Oliveira [2<\/a>]).SCB is generically composed of cellulose (50%), hemicellulose (25%), and lignin (20%) [2<\/a>].<\/p>\n\n\n\n Two types of soils were used separately, and Figure 2<\/a> shows their particle size distribution curves. The soil used in the first and second trial mixes came from Alentejo, a southern region of Portugal, designated here as Soil 1. It has a good granulometric distribution, with 15.9% of gravel, 47.2% of sand, 17.6% of silt, and 19.4% of clay. The percentage of clay in this soil is considered sufficient for construction, as it reaches just over 20% of the analyzed volume. Soil sifting is necessary to adjust the amount of gravel and obtain 4 mm as the maximum dimension. In the third trial mix, soil from Labruge, Vila do Conde, designated here as Soil 2, was used. This soil presented 65% of fine material (silt + clay), with the clay fraction equivalent to 15%. The type of aggregate present is fine sand, with a maximum diameter of 2 mm and with a well-graded granulometry distribution. The percentage of sand present in this soil is small.<\/p>\n\n\n\n Figure 2.<\/strong> Particle size distribution of the soils used.<\/p>\n\n\n\n Hydrated aerial lime (calcium hydroxide), manufactured in Portugal, was used. It is calcium lime, classified as CL90-S according to the EN 459-1:2015 [22<\/a>] standard, which has an apparent density of 0.46 g\/cm3<\/sup>.<\/p>\n\n\n\n Metakaolin is obtained from the calcination (at temperatures between 700 and 800 \u00b0C) of kaolinitic materials, which is a mineral clay with a high content of silicon dioxide. The reaction of metakaolin with lime produces hydrated calcium silicate (CSH) and aluminum hydrates. Processed with less energy than cement, metakaolin is used as a pozzolana to improve the mechanical strength of mixtures with lime or cement. The metakaolin used in this study was produced in Portugal and is characterized by a light orange color, which influences the final composite color. The main components of its chemical composition are the silica (60.7%) and alumina (34.3%) according to the producer\u2019s datasheet, mentioned by Kropid\u0142owska [13<\/a>].<\/p>\n\n\n\n For the use of SCB ashes in this research, a portion of SCB, 800 g, was placed into the muffle furnace at 600 \u00b0C. The process was carried out in 3 cycles: heating (1 h), burning (4 h), and cooling slowly, obtaining 106 g of ash. It was observed that this process did not produce calcination identical to that of the industrially obtained process, as the reference studies indicate that the ASCB corresponds to 0.6% of the initial weight of the SCB [23<\/a>], and was obtained here in the proportion of 13.25% of the initial weight of the SCB.<\/p>\n\n\n\n An outline of all the steps carried out in the methodology can be seen in Figure 3<\/a>. <\/p>\n\n\n\n Figure 3.<\/strong>\u00a0Stages of the study and the purpose of each.To prospect the material, potential preliminary mixes were prepared to evaluate the binder amount of water necessary to form a composite with adequate workability and minimum resistance for the manufacture of the blocks, to establish a plan in line with the intended results. The results obtained in this preliminary stage were guidelines for the planning of the 1st trial mix of the work. Three different trial mixes were then carried out, as shown in\u00a0Table 1<\/a>.<\/p>\n\n\n\n To verify the workability of the composites obtained, an empirical test known as the \u201cball method\u201d was carried out, which consists of taking a sample of the mixture and making a ball by hand. If the ball remains well formed and with good consistency, it means that the workability of the material is suitable to produce specimens, as was used by Martins in soil mixtures for compressed earth [24<\/a>], and, in this case, its procedure helps to verify the adhesion of the materials.<\/p>\n\n\n\n Specimens measuring 40 \u00d7 40 \u00d7 160 mm (Figure 4<\/a>a) were used for mechanical resistances and water absorption by immersion test, while specimens measuring 150 \u00d7 150 \u00d7 59 mm (Figure 4<\/a>b), dimensions compatible with the hot box, were only used for the thermal conductivity test.<\/p>\n\n\n\n Figure 4.<\/strong> (a<\/strong>,b<\/strong>). Specimens for general tests (a<\/strong>) and sample for thermal conductivity (b<\/strong>).The mixing process was carried out in a pan mixer with a rotating drum. The procedure is based on the methods used to produce hemp concrete, such as those used by Kropid\u0142owska [13<\/a>]. Water was added partially before and after the binder (\u2153 of the amount before and the rest after). Each sample was manually compacted in three layers, using a stone block and a rubber mallet to compact evenly. The formwork took place after 2 h of rest and the specimens were stored in a dry, semi-closed cupboard, at room temperature and humidity for the curing process (around 20 \u00b0C and relative humidity of approximately 50%).<\/p>\n\n\n\n The mixtures made were tested for their mechanical performance: concerning resistance to compression and bending, at 28, 60, and 90 days, with the exception of the mixtures from the second trial mix, which, due to the COVID-19 pandemic, were only tested at 28 and 90 days.The flexural strength tests were carried out in accordance with EN 1015-11:1999 [25<\/a>]. Tests were conducted on Lloyds Instruments (universal test hydraulic press with a maximum capacity of 50 kN), with an applied load of 10 N\/s. Three to six specimens were used per lot.The compressive strength tests were carried out in accordance with the EN 1015-11:1999 [25<\/a>] standard, using the parts left after the rupture of the specimens used in the bending test. A force of 10 N\/s was applied in the most unfavorable direction, perpendicular to the compaction of the fibrous material. With regard to the performance against the water action, tests of water absorption by capillarity and by immersion were carried out. The fibrous nature of the SCB and the porous nature of the raw soil demanded an adaptation of the measurement process of the capillary water absorption test, commonly presented by EN 1015-18:2002 [26<\/a>]. The method used was described by Hall and Djerbib [27<\/a>] and this was applied to obtain a good indication of the performance of compacted earth blocks, which is an adaptation of the British Standard BS3921 (IRS) test [28<\/a>]. Called IRS Oasis, the method was very useful, due to the special vulnerability of earth and fiber when in contact with water. For the test, specimens of 40 \u00d7 40 \u00d7 160 mm were used, one of each mixture from the first and second trials (213 and 107 days, respectively), cured at room temperature and humidity. The specimens were cut in half, measured, weighed, and arranged on a spongy block (known as Oasis) immersed in a box with water until its maximum absorption capacity stabilized. The Oasis was kept saturated, with 2 cm out of the water, as seen in Figure 5<\/a>. The contact times began to be measured and the samples were weighed after 5, 10, 15, and 30 min and then 1, 2, 3, 4, 5, 7, 9, and 24 h.<\/p>\n\n\n\n Figure 5.<\/strong>\u00a0Specimens cut and accommodated over the saturated Oasis.Regarding water absorption by immersion, specimens measuring 40 \u00d7 40 \u00d7 160 mm were used. One from the first trial mix at 210 days of curing and two from the second, at 105 days, always under the same conditions of ambient temperature and humidity. After drying in an oven at 60 \u00b0C, they were immersed in water at room temperature. After the first hour, the specimens were removed from the water and excess water was removed with absorbent paper. Then, they were weighed and returned to the water, where they remained for 24 h, calculating the water absorption after this time. At the end of the absorption period, the specimens were subjected to the compressive strength test, according to the procedure described above, to measure the loss of strength due to exposure to water. However, only the SCB with lime and SCB with lime and soil specimens were subjected to the test, as the specimens without hydraulic binders were very fragile and would not withstand the immersion test. As it is possible that the SCB composite has a thermal performance similar to that of hempcrete, a specimen of the BC1 mixture (150 \u00d7 150 \u00d7 59 mm) was prepared to be evaluated. The thermal performance of SCB composites was evaluated by considering their thermal resistance (Re) and thermal conductivity (\u03bb). These parameters were determined using a calibrated hot box designed and built at the Department of Civil Engineering of the University of Minho [29<\/a>], based on ASTM specifications ASTM C1363-19 [30<\/a>].\u00a0The hot box is composed of two chambers, the cold and the hot one, and one mounting ring is placed between the two chambers (Figure 6<\/a>). The SCB composites were placed in the center of the mounting ring.\u00a0<\/p>\n\n\n\n …<\/p>\n\n\n\n … you may find the complete article under https:\/\/www.mdpi.com\/1996-1073\/16\/1\/398<\/p>\n","protected":false},"excerpt":{"rendered":" Each year, hundreds of millions of tons of processed sugarcane generate, by weight, 25 to 30% of bagasse as waste, whose destination is combustion for energy cogeneration. This research proposes an alternative and more sustainable use for this waste. The use of sugarcane bagasse (SCB) as the single aggregate in composites for building blocks was […]<\/p>\n","protected":false},"author":59,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"The materials used in the experimental research were sugarcane bagasse (SCB) as an aggregate; aerial lime, SCB ash, Alentejo and Labruge soil, and metakaolin as binders; as an additive, sodium borate or borax","footnotes":""},"categories":[5572],"tags":[5838,5842,12447,11785,11749,11323],"supplier":[2154],"class_list":["post-121873","post","type-post","status-publish","format-standard","hentry","category-bio-based","tag-bioeconomy","tag-biomass","tag-buildingmaterials","tag-composites","tag-construction","tag-naturalfibers","supplier-university-of-minho-uminho"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/121873","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=121873"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/121873\/revisions"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=121873"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=121873"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=121873"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=121873"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}1.2. The \u201cSugar Cane Concrete\u201d<\/h3>\n\n\n\n
1.3. The \u201cHemp Concrete\u201d and Other Lightweight Concretes with Agroindustry Wastes<\/h3>\n\n\n\n
2. Materials and Methods<\/h3>\n\n\n\n
2.1. Materials<\/h3>\n\n\n\n
2.1.1. Sugarcane Bagasse\u2014SCB<\/h3>\n\n\n\n
![\"Energies](\"https:\/\/www.mdpi.com\/energies\/energies-16-00398\/article_deploy\/html\/images\/energies-16-00398-g001-550.jpg\")
<\/figure><\/div>\n\n\n\n2.1.2. Used Soils<\/h3>\n\n\n\n
![\"Energies](\"https:\/\/www.mdpi.com\/energies\/energies-16-00398\/article_deploy\/html\/images\/energies-16-00398-g002-550.jpg\")
<\/figure><\/div>\n\n\n\n2.1.3. Hydrated Lime<\/h3>\n\n\n\n
2.1.4. Metakaolin<\/h3>\n\n\n\n
2.1.5. Ashes of SCB (ASCB)<\/h3>\n\n\n\n
2.2. Methods<\/h3>\n\n\n\n
2.2.1. Mixtures<\/h3>\n\n\n\n
![\"Energies](\"https:\/\/www.mdpi.com\/energies\/energies-16-00398\/article_deploy\/html\/images\/energies-16-00398-g003-550.jpg\")
<\/figure><\/div>\n\n\n\n![\"Table](\"https:\/\/renewable-carbon.eu\/news\/media\/2023\/01\/Bildschirmfoto-2023-01-30-um-11.02.58.png\")
2.2.2. Manufacture and Curing Conditions of Samples<\/h4>\n\n\n\n
![\"Energies](\"https:\/\/www.mdpi.com\/energies\/energies-16-00398\/article_deploy\/html\/images\/energies-16-00398-g004-550.jpg\")
<\/figure><\/div>\n\n\n\n2.2.3. Performed Tests<\/h4>\n\n\n\n
![\"Energies](\"https:\/\/www.mdpi.com\/energies\/energies-16-00398\/article_deploy\/html\/images\/energies-16-00398-g005-550.jpg\")
<\/figure><\/div>\n\n\n\n