Influence of P(V) on the characteristics of calcium silicates and the hydration of clinkers

The effect of the addition of small amounts of meat and bone meal (MBM) ash on the clinkering process and on the hydraulic reactivity of obtained clinkers was studied. The study was aimed at simulating the clinker burning process in an industrial furnace that replaced up to 20 wt% conventional fuel with MBM used as alternative fuel. Laboratory clinkers were obtained by adding from 0.07 to 0.88 wt.% of MBM ash to an industrial raw mixture, and were compared with a clinker obtained without additions. The free lime content in the clinker increased steadily when the concentration of phosphorus was increased up to a level of 0.16 wt% P₂O₅ in the raw mixture. With higher phosphorus additions the free lime content increased only insignificantly. The results of X-ray microanalysis indicated that a maximum of 2.3 and 3.3% of the silicon sites were replaced by phosphorus in alite and belite, respectively. The clinker containing 0.6 wt% P₂O₅ slowed down the hydration process for approximately 1 day and thereafter began to exceed the degree of hydration of the reference sample. The values of degree of hydration of clinker rich in P₂O₅ exceeded the reference sample at 7 and 28 days by approximately 3 and 5%, respectively.