Cement, Energy and Environment

Table-2 Test results on neat cern t . h en Wit and without coconut shell fines Initial setting time Final setting time 76Min 88Min Not less than 30 min mixture containing fines of cement with coconut shell fragments(h) ; and Se is the maximum slope of neat cement ('C/h); and Sec is the maximum slope of the mixture containing fine of cement with coconut shell fragments('C/h). The test results are presented in Table 2. 7 hrs 10 min 9hrs 50 min Not more than 10 hrs 3. Compressive strength 3 days 28.12 N/mm 2 22.89 N!mm 2 27.00 N!mm 2 7 days 38.26 N/mm 2 28.78 N!mm 2 37.00 N!mm 2 4. Hydration test (i) Maximum hydration temperature 73'C 63' C Greater than 60'C Results and Discussion The (ii) Maximum slope 11 .35' C/h 7.55' C!h normal consistency of the neat cement and coconut shell fines with neat cement is found to be 31% and 38% by weight of 5. I <10 Low Inhibitory index (1)% 2.59% 1 = 10-50 Moderate I = 50-HlO High comprised 15gCS fines/200g Portland cement/90.5ml distilled water. Control samples were also prepared with neat cement (Portland cement and distilled water) for comparison. Each 15- g CS fines was dry-mixed with 200 g of cement in a polythene bag , then wetted with distilled water and mixed until homogenous mixture was obtained. The mixture was transferred to a Dewar flask and a thermocouple was inserted to enable temperature measurement at 1-min intervals over a 24-h period (Figure 5). Three replicates were used. The time expired to achieve the maximum temperature (Figure 6) and maximum slope of the curve (Figure 7) were assessed. The inhibitory index (I) for the test sample was calculated by using the Equation-1 (Esmeralda et al, 2004). I=[{(Te- Tcc)!Tc}* {(Iee - te) ftc} *{(Se-Scc) /Se}) *1 OO-----Eq.(1) I > 100 Extreme . Where I is the inhibitory 1ndex (%}; Te is the maximum temperature of the neat cement('C); Tee is the maximum temperature of the mixture containing fines of cement with coconut shell fragments ('C); tc is the time to reach maximum temperature of the neat cement (h); tee is the time to reach maximum temperature of the cement respectively. The result shows that the mix containing coconut shell fines required more water to obtain same consistency compared with neat cement. This may be due to the high water absorption of the coconut shell fines (Gunasekaran and Kumar. 2008 a and b) . The initial setting time and final setting time of neat cement are found as 76 minutes 54