Cement, Energy and Environment

r~ . ..._ --4- \ 100 90 8 0 Q> 'tl 70 "' .... 60 Ol ·~ Cl) so 0 £ a. 40 E Q> 1- 30 20 10 0 0 10 20 30 ---+---Neat Cement -a- Neat cement with Coconut sl1ell (2008) for wood aggregates that extend the setting time of neat cement by not more than 50% should be considered suitable Time in Hours and requi res no (further) pre– treatment; those that extend it by between 50% and 100% should be considered acceptable and further pre-treatment recommended; while those that extend it beyond 100 % should 100 90 80 ., 70 '0 "' .... .~ 60 Fig 6 Hydration Temp Vs Time .-- ~ --Neatcement be considered inhibitory and (further) pre- treatment highly recommended. In this study, setting time CS fines with E ., () 50 +l--~........::m~u~~"-:-:::-----'-"-_..:;..-7--:-1 I • Cementw~h coconutshell neat cement is less than 50% and hence, it is suggested that no pre-treatment is required for coconut shell fine-cement composites. ,.. g. 40 i 30 ..... 20 10 0 0 5 10 15 Time in Hours Fig 7 Maximum slope of hydration Temp and 7 hours 10 minutes respectively. Similarly, neat cement with coconut shell fine particles is found 88 minutes and 9 hours 50 minutes respectively. The result showed that, the setting of CS fines/cement composites is delayed compared with neat cement composites; it is probably due to the presence of botanical components and some water soluble sugars in CS that inhibit the setting and hardening of cement (Miller and Moslemi 1991 ). And, these components are sugars (glucose, sucrose), hemicelluloses, tannins, extractives, and other water– soluble substances (Moslemi A.A and Lim YT, 1984). However, if the final setting time is less than or equal to 15 hours, it is suitable for aggregate/cement compatibility. It was also suggested that, if the ratio of final setting time of wood-cement to neat cement composite lies in the range of 1.00 to 1.50, the mixture is compatible (Oiorunnisola, 2008). In this study, this ratio was found as 1.37 and therefore the coconut shell-cement composites are compatible. As recommended by Olorunnisola The compressive strength of mortar cubes of neat cement are 28.12 N/mm 2 and 38.26N/mm 2 at 3- days and 7-days respectively and satisfied the code requirements (IS 12269: 1987). The compressive strength of CS fines in the mix was found to be 22.89 N/mm 2 and 28.78 N/mm 2 at 3-days and 7-days respectively. These values are below the IS 1269: 1987 code requirements. This shows that, the required compressive strength can be achieved by adding more quantity of cement compared with neat cement composites. It is probably due to the relatively low density of the coconut shell particles (Gunasekaran and Kumar, 2008 a and b). The 55