Large number of experimental data were used to

Large number of experimental data were used to develop these correlations between mechanical strength and durability of the RHA added cement concrete. A least square method was employed to arrive the empirical constants and model parameters with higher accuracy. And the final models are given in the following Eqs. (4.5), (4.6), (4.7). From the above three equations, it has been observed that the size reduction ratio, pozzolanicity, specific surface area, curing time and the thermal diffusivity are the stronger functions of determining the strength of RHA added cement concrete. The remaining factors like RHA loading, silica content and the ratio of FM and LOI becomes secondary since the individual effect of silica content in RHA plays a vital role in strength development. In addition, the silica content of different types of RHA used in this study were insignificant among them. Fig. 10 shows the comparison between the measured values of compressive strength, compressive strength after Oltipraz and alkali attack, and the values predicted by the model represented in Eqs. (4.5), (4.6), (4.7). The model appears to be able to predict the mechanical strength and corrosive resistance of the RHA added cement concrete quite accurately with >90 confidence. Model based trial concrete mix can be performed with highly parameterized developed accurate empirical models, particularly when predicting highly nonlinear responses such as concrete strength under various corrosive environment and various % of RHA replacement in concrete. In an alkaline and acid environment certain properties like magnitude of corrosive nature of the environment, % RHA replacement, particle sizes and curing period needs to be carefully ascertained in concrete making process in order to develop the strength of concrete that are implemented in this model. Since the model comprising of numerous important influencing factors furnishes the convenient way of screening the high strength concrete mix trials. Within the availability of large number of experimental data, it is easy to develop the relation between the mechanical strength and corrosive resistance of the RHA added cement concrete. The developed correlation is given in the following Eq. (4.8). This equation can be used to predict any of the property mentioned above with order of high accuracy. The detailed statistical analysis of the models are described in the next section.
Statistical validation of experimental results T-test analysis was carried out for assessing statistical significance of the obtained experimental data. This test may be used to identify a parameter which has significant effect on concrete strength and corrosive resistance. Critical value of t was found from T table using degrees of freedom. Confidence level of each parameter was arrived by comparing absolute T statistical value and T critical value. Table 2 shows that T statistical value and the corresponding confidence level of each parameter. From Table 2, size reduction ratio, pozzolanicity, specific surface area, curing time and the thermal diffusivity are the key parameters in producing high strength and corrosive resistance cement concrete excluding RHA loading, SiO2, FM and insignificant variation in its physical properties.