| Summary: | 碩士 === 國立宜蘭大學 === 土木工程學系碩士班 === 100 === This study replaced fine aggregate with silicon particles (passing 4.76 mm) and cement with silicon powders (passing 0.076 mm) from discarded amorphous solar panels. Then we examined the properties of fresh and hardened concrete including the microstructure and durability. Those materials obtained from the discarded amorphous silicon solar panels with a high proportion of silicon dioxide. The test results of amorphous silicon solar panels demonstrate that the chemical composition of SiO2+Al2O3+Fe2O3 exceeded the 70% required by ASTM C618 specifications. Strength activity index (SAI) tests demonstrated the pozzolanic reaction activity.
First, the amorphous silicon particles were used to replace fine aggregate in the production of controlled low strength materials (CLSM) to determine their properties. Second, we grind the amorphous silicon particles into powders. Then we utilize the amorphous silicon particles and powders to replace fine aggregate and cement in mortar, respectively. Finally, the amorphous silicon powders were used to produce concrete and alkali-activated concrete.
Results show that the particles and powders both enhance the workability of the mortar. The substitution of these materials in low quantities (particles replace fine aggregate 10%~20%; powders replace cement 5~10%) can enhance the compressive strength in all stages of hardness development. At higher quantities (particles replace 30%~50% of fine aggregate; powders replace 15~20% of cement), compressive strength increased in later stages. According to SEM results, amorphous silicon particles and powders can increase compressive strength in later stages; however, they do not enhance the durability of mortar.
Experimental results demonstrate that increasing the consistency of sodium hydroxide reduces the performance of alkali-activated concrete despite shortening the setting time. Our results demonstrate that the addition of sodium hydroxide is insufficient to activate amorphous silicon powders.
|
|---|
