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Report of Concrete Slab Evaluation RE&A Project No. 2825-15-023-SE-A Existin�TKM Aviation Han�ar June 27. 2017 Evaluations and Conclusions Based on the review of the current surface and subsurface conditions, e�sting soil and groundwater water data, laboratory test results, the following evaluations and conclusions are formulated: . • The subsurface soils constitute competent soils. Even though the sands utilized for compacted fill indicated fines content (percentage of clay of 29%) much higher than recommended (less than 12%), given that soils were fairly compacted with equivalent N- values in the range of 8 to 24 BPF, with an average of 18 BPF, and that they are at a higher elevation than the zone of fluctuating water level (active zone), and that the thickness of this layer itself is limited to 1 to 1.5 feet, it is our professional opinion, within a reasonable engineering probability that probability of expansion and contraction, and/or consolidation settlement of this layer is quiet low, and hence did not contribute to the concrete slab distress. • Based on the results of petrographic examinations and concrete strength testing, it is our professional opinion within reasonable engineering probability that the concrete placed at the project site was as specified in the concrete mix design, and is fairly hard and dense with strength equal to, if not exceeding, the requirements. However, given that the concrete was placed in hot summer months, it is our professional opinion that inadequate protection against rapid moisture loss during the curing process, may have contributed to the shrinkage cracks experienced by the slab. It was also observed that the concrete appeared to have experienced rapid set at several locations. It is important that the concrete slab surfaces must be protected from rapid drying in the first several days as the concrete cures and hardens. It is usually accomplished by avoiding hot and dry conditions,by scheduling concrete pours during night time, and then prevent evaporation by use of a combination of ponding, sprinkling and wet mats. In our professional opinion, it can be concluded that the concrete slab cracking is a result of drying shrinkage during placement and initial curing of the plastic concrete and the structural load carrying capacity of the slab-on-grade has not been compromised. 6