Microstructure and compressive properties of silicon carbide reinforced geopolymer

Abstract

Geopolymers (GPs) have emerged as a promising alternative to ordinary cement due to its attractive physical and thermal properties. The typical compressive strength of geopolymers and their composites is usually limited to around 80 MPa, therefore they should be further strengthened for wider applications, such as ultrahigh strength concrete, and bone replacement. This paper presents a facile method of enhancing the compressive strength by incorporating silicon carbide particles (SiC p) and silicon carbide whiskers (SiC w) into the geopolymer matrix via the geopolymerization of metakaolin (MK). The effects of the reinforcement of SiC p and SiC w on the microstructure, thermal properties and compressive properties of the composites were investigated. The SEM images showed that both SiC p and SiC w were well dispersed in the geopolymer matrix. Due to the bridging effect among the SiC w particles, SiC w /GP composites possessed higher porosity and lower density, and thus lower thermal stability and thermal conductivity as compared with SiC p /GP. The mechanical tests showed that the compressive strength of SiC p /GP composites increased with the increase of SiC p concentration. With an optimum concentration of 10 wt. % of SiC p , the compressive strength of the composite was enhanced to 155 MPa, corresponding to a 100% increase as compared with the unfilled geopolymer.

Utilization of Thermally Treated SiC Nanowhiskers and Superplasticizer for Cementitious Composite Production

“…Regarding the mixes with SP, the higher the NWs content, the higher the thermal conductivity, reaching thermal conductivity values of 77.1% and 79.2% higher for NT-NW_SP_1.00% and 500-NW_SP_1.00%, respectively, compared with plain cement paste. These results agree with those reported by Du et al [ 20 ], who observed increases in the thermal conductivity of geopolymer-SiC composites and this was expected since SiC whiskers are excellent heat conductors [ 20 , 42 ]. Similar results were also reported for the cementitious matrix reinforced with carbon nanotubes [ 43 ].…”

“…Rahman and Al Rashed [ 19 ] incorporated 5–20 wt % SiC NWs in aluminum matrix composites, observing progressive improvements in their mechanical performance as the incorporation level increased, reaching 85% higher Vickers hardness and 173% higher tensile strength values for the highest incorporation level in comparison with the plain matrix. Du et al [ 20 ] produced geopolymeric composites with 1–10 wt % addition of SiC NWs, reaching a 28-day compressive strength of 155 MPa, corresponding to a 100% enhancement compared with the plain matrix. Shui et al [ 21 ] successfully produced porcelain ceramics with 1–3 wt % SiC NWs incorporation.…”

Análisiscomparativodelas propiedades mecánicas de geopolímeros queincorporannanowhiskersdeSiCynanopartículasdeTiO2

“…Conforme a la registrado por [45] la adición de SiC en la forma de fibras hasta de 2 % en volumen contribuye al aumento del 36,70 % de la resistencia a la compresión. Sin embargo, en la forma de whiskers [46] registra decrecimientos en la resistencia cuando son incorporados más de 5 % en masa. Ambos usando matriz geopolimérica a base de metacaolin Este último autor indica que, en la forma de partículas el SiC ayuda en efecto de relleno, registrando mejor empaquetamiento que los whiskers y, por lo tanto, contribuyen considerablemente a la resistencia a la compresión, con un incremento de hasta 102 % en la matriz.…”

An Application Review of Fiber-Reinforced Geopolymer Composite

“…The addition of E-glass fibers increases the deflection of the composite that leads to failure. The optimized hybrid FRGC configuration demands high specific strength and stiffness [30][31][32]. The better adhesion of the geopolymer with fibers and concrete offers a good platform for use as repair and composite material.…”