Evaluation of usability of pozzolan reinforced construction and demolition wastes as a granular fill

In this study, the potential usability of construction and demolition wastes (CDW), which are not suitable for engineering applications, together with pozzolan and geogrid as a granular filling materials was investigated. For this purpose, test samples were prepared by adding 5%, 10%, 15%, 20%, 25% and 30% fly ash and blast furnace slag as an additive to the CDW. Compaction tests were carried out on samples with and without additives and then, unconfined compression and California bearing ratio (CBR) tests were conducted. Also, in these tests, alkali activator solution was used to increase the reactivity of pozzolans in the mixture. Unconfined compression and CBR tests were carried out at the end of 7 and 28 days curing periods. After determining the most effective additive rate, model loading experiments were executed. The load-deformation behavior of the model foundation was investigated by placing a model foundation on the unreinforced, geogrid reinforced, pozzolan reinforced, both pozzolan and geogrid reinforced CDW fill built on a weak soil. Model loading experiments were carried out after 7 days curing period. Experimental results indicated that the maximum dry unit weight (γkmaks) values decreased with increasing pozzolan additive ratio. However, the optimum fluid rate (ωopt or ωoptAAÇ) decreases, with an increase in a pozzolan additive rate, except for blast furnace slag. According to unconfined compression and CBR tests, 20% YFC additive with alkali activator has been determined to provide the highest strength value. This test sample's unconfined compressive strength was 14.72 and 23.20, CBR value was also 11.78 and 25.00 times higher than unreinforced test sample at the end of the 7 and 28 day curing periods, respectively. When model loading experiments were examined, it was determined that in the highest filling case, the strength of unreinforced, geogrid reinforced, pozzolan reinforced and pozzolan-geogrid reinforced CDW fill were 7.01, 8.93, 32.84 and 42.56 times higher than weak soil, respectively. As a result of this thesis, it was determined that the CDW fill have relatively low performance compared to the natural aggregate fill, but its performance can be increased by using geogrid and pozzolan. It was considered that using CDW aggregate instead of natural aggregate can make important contributions to both environment and economy. Therefore, it was predicted that recycling and re-using CDW materials in our country can make important contributions to our country.