# Agricultural Residues of Lignocellulosic Materials in Cement Composites
## 3 Results and Discussion

Table 3: Average and standard deviation of the physical properties of the lignocellulosic composites. values. Thus, although the literature has described pronounced effects of extractives on cement curing, for cement-based panels, there is a composite effect of the material's geometry and chemical composition on the density and porosity, thus significantly influencing the other physical and mechanical properties of the obtained cement-based composites. Table 3 shows the amount of water absorbed and the variation in the thickness during the first 2 h of immersion in water and between the first 2 and 24 h. Interestingly, the most significant absorption of water occurred during the first 2 h. After this period, the amount of water absorption was almost irrelevant for most materials, except for sugarcane (5.6%). In contrast, after the 2 h of contact with water, the cumulative thickness swelling was much greater than that in the first 2 h, except for coffee husk (0.8%). According to these results, the process of water absorption is faster than the thickness swelling. The increase in thickness after 2 h was probably associated with the large amount of water absorbed during the first 2 h. In this case, in a building using these lignocellulosic composites, the first 2 h of contact with water would be critical for the panel's water absorption and thickness, owing to the effects on the mechanical properties of the composites. Such water absorption by the particles must be avoided for good dimensional stability. The greater the dimensional variation, the lower the binding with the matrix; therefore, limiting water absorption is thus often desirable [44]. Lignocellulosic materials can absorb substantial amounts of water. Banana pseudostem panels absorbed 26.034% of their weight in water. According to [PERSON] et al. [9], a lower content of lignin results in higher hydrophilicity. Banana pseudostem had the least amount of lignin (Table 1) and the lowest density values, thus resulting in the highest WA values (Table 3). A direct effect of panel density on the properties WA2 h and WA24 h was also observed, in which the panels with the highest densities (eucalyptus, sugarcane bagasse, and coffee husk) showed the lowest water absorption values. The sugarcane panels notably showed low values of water absorption, which may be associated with the higher quantity of extracts in the sugarcane bagasse. Although the amount of extractives affects cement curing, when extractives are associated with the material, they can make the panels less hygroscopic [6; 11], particularly in the first hours of contact with water. However, although the sugarcane panels presented the lowest TS2 h, sugarcane and eucalyptus panels had the highest TS24 h values. This finding may be explained by the dimensional expansion of the materials (sugarcane and eucalyptus), which had lower density than the other materials (Table 2), thus promoting greater dimensional movement of the panels and consequently, their expansion in thickness. Although differences were observed among the panels with coffee husk, coconut shell, and 406 banana pseudostem, an evaluation of the density and porosity of these panels indicated that this effect was not reflected in the swelling in thickness (TS2 h and TS24 h). TS is more strongly influenced by the density of the lignocellulosic materials used to produce the panels. Thickness swelling is a critical parameter in the dimensional stability of composites. The composite thickness can also vary according to the moisture content, particularly during contact with water. The characteristics of composites with lignocellulosic materials immersed in water are influenced by the nature of the fibre and matrix materials, the relative humidity, and the manufacturing technique, which determines factors such as the porosity and volume fraction of fibres [45]. In a similar study, [PERSON] et al.