Assessment of Wood Bio-Concrete Properties Modified with Silane–Siloxane

Abstract

Bio-based materials, such as wood bio-concrete (WBC), hold promise in reducing energy consumption and carbon footprint of the construction industry. However, the durability of these materials is not well understood and can be negatively affected by the high water absorption capacity of wood bio-aggregates. In the field of cement composites, for example, silane–siloxane-based water repellent has been used to protect such materials from natural environmental attack. Nevertheless, there is still a limited understanding of various aspects related to this type of treatment, including its performance when applied to the bio-concrete substrate. This research aimed to investigate the influence of silane–siloxane on the rheology and hydration of cementitious paste through isothermal calorimetry and thermogravimetric analysis. Additionally, the impact of silane–siloxane on the physical and mechanical properties of WBCs was examined by conducting tests at fresh state (flow table and entrained air content) and hardened state (compressive strength and capillary water absorption). The composites were produced with a volumetric fraction of 45% of wood shavings while the cement matrix consisted of a combination of cement, rice husk ash, and fly ash. Silane–siloxane was applied in three ways: as coating, incorporated as an admixture, and in a combination of both methods. The results indicated that by incorporating silane in the cementitious pastethe viscosity increased by 40% and the hydration was delayed by approximately 6 h when compared to the reference. In addition, silane improved the compressive strength of WBCs by 24% when incorporated into the mixture, expressively reduced the water sorptivity of WBCs (93%), and was more effective if used as coating.

A Comprehensive Experimental Study on the Physical Performance and Durability of Bamboo Bio-Concrete

“…During the final sorptivity (S3), the BBC was practically saturated, and the absorption curve reached a plateau at the end of the test (h 0.5 = 25.92). The highest absorptions were from the BBC 2.5 mixture, which has the highest BP volume and consequently the greatest ease of water absorption due to the hygroscopic characteristic of biomass [8,18,27]. Based on the results reported in Table 4, the initial sorptivity of BBC 2.5 was 4.4 and 4.1 times higher than the secondary for water-to-cement ratios of 0.40 and 0.5, respectively.…”

“…As a matter of fact, according to the literature, the presence of bio-aggregates can affect the cement hydration processes in terms of setting time and mechanical strength development due to the presence of "extractives" within the bio-aggregates fraction [17,26]. For this reason, before being used in a cement matrix, BAs are submitted to pre-treatment to reduce inorganic substances and soluble extractives, in order to avoid the delay or inhibition of cement hydration [18,27,28]. On the other hand, da Gloria et al [16] determined the compensation water for each type of BA, using the water absorbed by the bio-aggregate during the production of the bio-concrete.…”

“…On the other hand, da Gloria et al [16] determined the compensation water for each type of BA, using the water absorbed by the bio-aggregate during the production of the bio-concrete. Bio-aggregates are characterized by speedy water absorption capacity compared to conventional concrete aggregates [9,16,18,27]. As a matter of principle, compensation water is additional water used to ensure that the BAs remain saturated and do not absorb the water of cement hydration.…”

“…Using this molding technique, it is possible to produce particle boards with a thickness of around 6 mm, obtaining density values between 1150 and 1350 kg/m 3 , thermal conductivity of 0.35 W/mK, and compressive strength and modulus of elasticity of 15 MPa and 4.5 GPa, respectively. They achieve adequate mechanical strength for non-structural applications [6,7,27,28,[33][34][35] and are classified as excellent materials in terms of hygrothermal performance [36]. These materials are generally used for façade cladding and insulation, partition walls, ceiling cladding, and interior decoration.…”