Cement, Energy and Environment

Fig.3.Crushed coconut shell Fig.4. Different sizes coconut shell Coconut Shell - cement compatibility requirements The term compatibility, when applied in the research area of coconut shell (wood) - cement concrete, refers to the degree of cement setting after mixing with water and with a given wood in a finer form. In general terms, if the chemical process of cement hardening is undisturbed, or disturbed to a small extent, by the presence of wood it is said that the cement and wood fines are compatible; on the other hand, if cement hardening is impaired by the presence of wood fines, then they are said to be incompatibility. Generally, the parameters that determine the compatibility requirements for the wood cement composite are maximum hydration temperature, time taken to attain maximum temperature, ratio of the setting times of wood– cement mixture and neat cement and also an inhibitory index (Esmeralda et al 2005, Olorunnisola, 2008). Inhibitory effect is the measuring of the decrease of heat release during the exothermic chemical process of cement hydration (Jorge et al., 2004). Hence, it is very much necessary to know the wood-cement compatibility (i.e) between coconut shell fragments with cement. Testing on cement with and without coconut shell Oridinary Portland cement 53 Grade conforming to Indian Standard code IS 12269: 1987 was used for conducting all the tests. Coconut shell husks were collected after crushing and the coconut shell using the mini crusher and the fines passing through Indian Standard Sieve No.9 (90 microns) are used for the test. Hereafter the coconut shell husks passing through 90 micron sieve are referred as CS fines. In addition to above mentioned, parameters required to assess the compatibility for the wood cement composite, the evaluation of coconut shell– cement compatibility can be done by measuring the properties such as normal consistency, initial and final setting times, compressive strength and hydration tests using the samples of CS fines with cement and neat cement. Hence, the effect of CS fines with cement can be evaluated on samples prepared using every 100 grams of cement and 7.5 gram of CS fines and on the mixture the consistency test, initial and final setting time tests were conducted using the standard Vicat mould apparatus and the compressive strength tests were also performed. In all the tests, the standard procedure was adopted and followed for the samples with and without CS fines. The results are presented in Table 2. Hydration test Hydration tests were conducted for both neat cement and cement with CS fines. The test was based on previous studies (Moslemi and Lim, 1984, Olorunnisola, 2008). The test was conducted in sealed thermally insulated containers (Dewar flasks). The CSfines/cement/water mixtures 53