Chemical composition, particle geometry, and micro-mechanical strength of barley husks, oat husks, and wheat bran as alternative raw materials for particleboards

Exploring Oat Husks as Aggregates in Limestone-Based Composites: Effects of Surface Treatments and Binder Selection on Mechanical Performance

“…Also, in Table 6 , the high percentage of initial moisture in the samples containing mineral particles may be associated with factors such as porosity, capillarity, and agglomeration, considering the particles’ visible size and surface area. The tubular internal structure of oat husks [ 2 , 60 ], associated with the increase in porosity, may also be related to the results observed in the washed husks (WOHs), in addition to greater exposure to chemical components with greater affinity with water, such as hemicellulose, since after immersion for 24 h, the sample absorbed almost twice as much water compared to the untreated material (COH). However, the lower values in the coated samples (LOHs), despite showing some absorption and being in line with the hydrophobic nature of the oil used, may suggest a failure in coating some particles.…”

“…In Figure 9, after utilisation in the cementitious matrix, it is possible to observe that the particles maintained their geometry yet exhibited similarities with those immersed in an alkaline environment (COH and WOH), revealing the removal of the layer formed after the coating treatment (POH and LOH). The untreated particles (COHs) exhibited a smooth and slightly translucent appearance, with barely visible grooves and white marks indicating the removal of the outer epidermis + cuticle [60]. The washed particles (WOHs) exhibited minimal modification, but it is possible to identify less smooth contours, indicating degradation.…”

“…The samples now exhibit a consistent pattern, though with discernible differences in intensities. The untreated particles (COHs) exhibited a smooth and slightly translucent appearance, with barely visible grooves and white marks indicating the removal of the outer epidermis + cuticle [60]. The washed particles (WOHs) exhibited minimal modification, but it is possible to identify less smooth contours, indicating degradation.…”

“…Additionally, there may be surface encrustation and the removal of coating layers due to enhanced one-side adhesion with the matrix or, possibly, due to friction and the formation of ettringite bridges [2], which could increase mechanical adhesion. The untreated particles (COHs) exhibited a smooth and slightly transluc appearance, with barely visible grooves and white marks indicating the removal of outer epidermis + cuticle [60]. The washed particles (WOHs) exhibited minim modification, but it is possible to identify less smooth contours, indicating degradati Significant changes were observed in the particles subjected to coating, where (PO appears to undergo a more substantial removal of the superficial layer, allowing visualisation of the original particle.…”

“…In terms of aggregate and bio-aggregate physical characteristics, the results in Table 6 show that, when considering the geometric properties of oat husks, their inherent tendency to retain their natural curved shape and known lower specific density [60] play a significant role in packing the particles and affecting the resulting bulk density. When comparing the untreated material with the husks after the washing cycles (WOHs), the reduction in density is consistent with the increase in particle porosity.…”