Fuzzy logic assessment of engineering properties of granular soil with wastes for environment protection and road base use

Afyonkarahisar is a city in Turkey and is rich especially with marble production. Therefore, marble dust piles occupy places in residential fields and agricultural lands or the vicinity of the marble manufacturing facilities. So, the use of those wastes with some amount of fly ashes with granular soils as admixtures for road constructions around the city will be great to protect the environment pollution and also to handle waste storage problems besides also improving the engineering properties and strength of these soils. However, assessing appropriate percentages of admixtures is a difficult task and requires performing many laboratory experiments considering different combinations and rates for each type of soil. So, the purpose of this study was to develop a practical method taking each possible marble dust and fly ash rates and their combinations into account for assessing the strength and compaction properties of granular soil used in road bases. The developed method may also reduce the number of laboratory experiments, lessen labor costs, and save experiment time. The model presented in this study is based upon the fuzzy logic inference method. The model contains two fuzzy input sets as the marble dust and fly ash and four fuzzy output sets as California Bearing Ratio (CBR), unconfined compressive strength (qu), dry unit weight (γdry) and water content (ωopt). The study results showed that the strength parameters as CBR and qu and compaction properties as γdry and ωopt of the granular soil with different combinations and percentages of marble dust and fly ash admixtures can be determined with high rate of confidences by using this model.