Page 85 - Demo

AAC WORLDWIDE %u2022 2.2025 PRODUCTION TECHNOLOGY 85One fundamental parameter in AAC production control is the Water to Solids (W/S) ratio. This ratio represents the total amount of water in the mix %u2013 including water from sand, return slurries, aluminum suspension, and both hot and cold water dosed into the mixer %u2013 relative to the total amount of dry solids. Water has the highest heat capacity of all substances, requiring 2257 kJ to convert 1 kg of water into steam. This energy demand must be supplied by the boiler. (Figs. 1 and 2)Cakes with excessive water content require longer autoclaving cycles, as additional energy is needed to convert excess water into steam. Reducing water content directly decreases energy consumption, leading to cost savings. Additionally, if autoclave capacity is a production bottleneck, shortening the autoclaving cycle can increase overall production capacity.Water's high heat capacity allows it to absorb energy from binder reactions immediately after casting. A higher water content results in cooler cakes, causing an energy imbalance. Insufficient cake temperature due to excessive water negatively affects reaction efficiency and reduces compressive strength. Practical implementation of additives has demonstrated that reducing water content alone can enhance compressive strength due to this mechanism.Energy Balance and the W/S RatioAccording to energy balance theory, a higher W/S ratio requires more energy to surpass the activation barrier. The correlation between W/S ratio and energy consumption is evident across different densities (300 kg/m%u00b3, 500 kg/m%u00b3, and 600 kg/m%u00b3) %u2013 see Fig. 3.Excess water can also cause sticking and difficulties in evaporating water from the cakes, increasing the risk of \claving cracks. More water in the autoclave leads to unnecessary condensate generation and potentially higher final product moisture levels.Reducing water content is essential for maintaining the thermal balance of the cake. Mixing tower operators should be aware of this before adding extra water to improve mass flow or mitigate cracks %u2013 an issue frequently encountered in production facilities.Strategies for Reducing Water ContentPoromix additives are designed to enhance both energy and mineral balance by:%u2022 Preventing coagulation: Allowing betterhydration and dispersion of particles.%u2022 Reducing water surface tension: Using surfactants to optimize water efficiency in the mix.Coagulation PreventionBy preventing coagulation, Poromix maximizes the effectiveness of binders, reducing the required quantity while increasing reaction efficiency. More hydrated cement and lime contribute to increased heat generation from these reactions.Water Surface Tension ReductionModern chemicals can replace excess water. Poromix functions as a surfactant, reducing water surface tension and allowing for greater hydration of raw material particles (Fig. 2). This effect enables similar Fig. 2: Phase transition of 1kg of water into steamFig. 3: Energy balance and Water/Solids ratio