Question

3. The large piece of concrete slab of dimension 1m x 2m weigh 100 kg. The drying curve for the concrete slab is as shown in Figure 3. Using the drying curve determine the time required to dry the concrete slab. If the initial moisture is 0.4 kg H2O/kg dry solid and final moisture is 0.1 kg H2O/kg dry solid. 110 marks (Hint: Use appropriate equations of time of drying for constant and falling drying rate) 20 2.0 Pain Paline - Constant Constant URE 01 02 03 04 05 06 Freemoisture X kg H,O/kg dry solid)

Answer 1

here some values taken from given graph and drying time calculate.calculation is done with the help of scientific calculator.

so":- Given data are - concrete slab of dimension IMX 2M Weight (w) = 100kg initiay moisture content (x1) = 0.9 finas moisture content (X2) = o.) kg 120 critical moisture content (xe) = 0.2 kg H2O from given graph equilibaium moisture cx*) = 0.05 from graph constant drying rate (Ne) = are content (x1) = 0.4 kg H20 13 toliy Kg dry solid F legary solid rying rate (Ne) = 1.5 kg 120 mehr so Now, first we calculate time for constant rate porioa - ws_(XI-Xe) te = AND ولا whore ws - weight of dry solid ws-WC1-2) = wl1 x) = 100 (1- ) = 71.428 kg A = Aner of slab - 1X2 - 2 m pe = constant rate period, 49120 te= drying time in constant rate, hy mehr tc - 8 (0.4-0.2) = 71.428 2x1.5 Gith ur tr = ANC similenly for falling rate period, drying time is ws (Xex) in /h 1.428 (0:2--05) in 2005 2X15 in T - tettf = 4.76+3.923 so total time of drying is T = tetto = 4.76+3.9. 0.2-0.05 sony 3.92 - 8.683hr