Study on the Performance of Rice Husk Ash as a Cementing Material

Abstract

Utilization of rice husk has become subject of growing interest. The possibilities of its utilization of rice husk in various ways have evoked much interest due to its high silica content. Particularly in the developing countries of South-east Asia where the production of rice is more than half of the production of entire world. Most important among various methods suggested for the utilization, is the development of construction materials from rice husk as such and from its ash. For every 1000 kg of paddy milled, about 220 kg (22%) of husk is produced, and when this husk is burnt in the boilers, about 55 kg (25%) of rice husk ash (RHA) is obtained. Rice husk ash is a great threat to environment causing damage to the land and surrounding area in which it is dumped. Rice husk burnt at 450CC have been found to produce a pozzolana conforming to the requirements of the ASTM standard C618-72. Therefore, valuable product from this rice hush ash (RHA) is possible. The rice husk For the study was collected from rice husking mill and was burnt in muffle furnace in laboratory (at 450°C) for 60 minutes. Rice husk is found to contain about 76.53 % organic volatile matter and the balance 23.47 % as ash (Table 3.7). The rice husk ash was grounded in laboratory by using Industrial Ball Mill to the form of powder. The particles finer than 200 meshes was collected for further test. The new product of RHA cement sample was tested for properties like Ordinary Portland Cement. RAH cement made in this study contains ash, lime and clay in different ratio. For this purpose a typical samples at the beginning was made with RHA (60%) mixed with finely grounded lime (30%) and un-burnt clay (10%). Similar samples were made with burnt (800 °C) clay. The result between two are found to agree. Rest of the cement samples were made with Un-burnt clay and burnt clay. Results of these samples are shown in table no. 4.1, 4.2, 4.3, 4.4, 4.5. By discussion the test results we find that, (a) in case of un-burnt clay, average water-cement ratio required for cement paste of normal consistency (CPNC) was found to be 0.56, initial setting time was found to be 96 minutes, final setting time was found to be 6 hrs. 58 minutes. and 3 days compressive strength for cement mortar cube was found to be 171 psi. respectively. (b) in case of burnt clay, average water- cement ratio required for cement paste of normal consistency (CJNC) was found to be 0.56, initial setting time was found to be 96 minutes. final setting time was found to be 7 hrs.13 minutes and 3 days compressive strength for cement mortar cube was found to be175 psi respectively. These values when compared with those of Ordinary Portland Cement, it was found that in case of un-burnt clay, CPNC varied only 7%, initial setting time was double than OPC, final setting time was increased by one

hour than OPC. (b) in case of burnt clay, CPNC was found to be 0.56, initial setting time was found to be more than double than OPC, final setting time was increased by one and half hour than OPC and 3 days compressive strength was found to be 175 psi. It is clear from the study that RHA can be attributed cementing property when combined with lime and clay. The properties of this cement resembles with those of OPC with compromise of' higher setting time and lower strength. However this may be recommended for the cases where lower strength can be used (e.g., boundary walls, normal load bearing residential buildings, partition walls, surface drains etc.)