IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 04 Issue: 03 | Mar-2015, Available @ http://www.ijret.org 454 EFFECT OF VINSUPERPLAST ON THE HYDRATION STUDY OF RICE HUSK ASH BLENDED CEMENT Sukirti Gupta 1 , Anamika Singh 2 , N.P Singh 3 1 Department of Chemistry, Udai Pratap (Autonomous) College, Varanasi, India 2 Department of Chemistry, Udai Pratap (Autonomous) College, Varanasi, India 3 Department of Chemistry, Udai Pratap (Autonomous) College, Varanasi, India Abstract For civil engineering the basic need is to produce high quality and high strength concrete. superplasticizers are used as high range water reducer and they improve the workability of concrete and mortar. In the present work several experimental programmes have been carried out in order to study the effect of Vinsuperplast on RHA blended cement. 2% Vinsuperplast with RHA blended cement and ordinary Portland cement increases the hydration and strength of cement which was measured by consistency measurement, setting time, non-evaporable water content, and free lime determination. 20% RHA blended cement gives better results in comparison to 10% RHA blended cement. The hydration mechanism of RHA blended cement with Vinsuperplast were tried to understand by using XRD, DSC and SEM techniques. Keywords: OPC (Ordinary Portland cement); Vinsuperplast (superplasticizer); RHA (Rice husk ash) Blended cement; XRD; SEM; DSC. -------------------------------------------------------------------***------------------------------------------------------------------- 1. INTRODUCTION In order to save resource and energy, it is now a common practice to use blended cement, made from Portland cement and agricultural / Industrial wastes [1-5] . The aim of blending is to utilize the agricultural and industrial wastes to produce high quality and high strength cement, which reduces the environmental pollution. [6-8] Rice husk is the outer cover of paddy and accounts for 20-25 % of its weight. It is removed during rice milling and is used mainly as fuel for heating in Indian homes and industries. Its calorific value is 13-15 MJ/kg and is lower than most woody biomass fuels. However, it is extensively used in rural India because of its widespread availability and relatively low cost. The annual generation of rice husk in India is 18-22 million tons and this corresponds to a power generation potential of 1200 MW. Few rice husk-based power plants with capacities of 10 MW are already in operation and based either on direct combustion or through fluidized bed combustion. [9-10] Research on producing rice husk ash as a blend for cement is not new [11-12] . Pitt developed a fludized bed furnace for the controlled combustion of rice husk at a fixed temperature and heating time give highly pozzolanic rice husk ash [13] . Rice husk is characterized by low bulk density and high ash content (18-22% by weight). The large amount of ash generated during combustion has to be continuously removed for a smooth operation of the system. Silicon oxide is the main component (90-97%) of the ash with trace amounts of CaO, MgO, K 2 O and Na 2 O [14-15] . The use of RHA in concrete has been associated with the following essential assets. Increased compressive and flexural strengths [Zhang et al, 1996; Ismalia 1996; Rodriguez 2005], reduced permeability [Zhang et al; 1996; Ganesan et al; 2007], reduced effects of alkali silica reactivity [Nicole et al 2000], enhanced workability of concrete [ Counthio 2002; Habeeb et al 2009; Mahmud et al 2004], reduced amount of superplasticizer [Sata et al 2007]. Various studies have been published that deal with the effect of superplasticizer on the physiochemical properties of Ordinary Portland Cement [16-20] Superplasticizers are linears polymers containing sulphonic acid groups attached to the polymer backbone at regular intervals. Superplasticizers are broadly classified into four groups, sulfonated melamine-formaldehyde condensates (SMF), sulfonated naphthalene-formaldehyde condensates (SNF), modified lignosulfonates (MLS), and polycarboxylate derivatives. Many group of scientists investigated hydration of ordinary Portland cement and mechanism of interaction with superplasticizer. [21-24] The molecular structure of polycarboxylate (PC) superplasticiser admixtures is shown in Fig.1 [25-27] their ‘comb-type’ molecule consists of one main linear chain with lateral carboxylate and ether groups. According to the literature the carboxylate groups are instrumentalin the adsorption of these admixtures to cement particles. Dispersion is due to electrostatic repulsion (as in melamine and naphthalene admixtures) owing to the carboxylate groups, but primarily to the steric repulsion associated with the long lateral ether chains. The high degree and duration of the fluidity that this admixture affords concrete are related to structural factors. The long lasting fluidity is