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CONCRETE PRODUCTS & CAST STONE88 CPI %u2013 Concrete Plant International %u2013 1 | 2026 www.cpi-worldwide.comwell by the investigation of the hydration heat development of white cement (see Diagram 2).It can be seen that the higher the temperature during curing, the faster the hydration heat contained in the cement is released. This means that active heating can help to at least partially compensate for the lower hydration heat of sustainable cements when it comes to achieving high early strength. Active heating of the curing chambers allows sustainable cements to be used and CO2 emissions to be reduced without having to accept any major disadvantages in terms of curing.One could argue that the reduction in CO2 emissions achieved by using sustainable cements might be offset by the emissions generated through active heating of the curing chambers. However, it must be borne in mind that even CO2-reduced cements still require a large amount of thermal energy during production, even though this has been reduced by a considerable 10%u201330% for CEM II and even 20%u201340% for CEM IV compared to CEM I. The thermal energy requirements for active heating of the curing chambers are comparatively low. It can be estimated that active heating only consumes around 3-5% of the above-mentioned thermal energy savings. These figures seem plausible when one considers that increased curing temperatures currently range between 30-35 %u00b0C and not hundreds of degrees as in cement production.Although many concrete product manufacturers already have active heating in their curing chambers, not all producers are equipped with it yet. The reason for this is certainly the associated investment and operating costs. However, it can be expected that investing in active heating of the curing chamber will also be financially worthwhile in the future, considering that CO2 emissions are factored into the price of cement and the cost of CO2 certificates is rising.When evaluating active heating, it should also be taken into account that an increase in cement costs is to be expected. The reason for this is that, in Europe for example, CO2 certificates (\imports of low-cost cement in order to avoid distortions of competition. Active heating can also help here, as the faster development of hydration heat tends to reduce cement consumption. This makes it possible to offset higher cement costs to a certain extent. However, this must be checked for each individual application.If active heating offers the possibility of compensating for the disadvantages of CO2-reduced cement in the curing of concrete products, the question naturally arises as to which heating technology is best suited for this purpose. The following section provides some basic information about the various energy sources to help you choose the right heating technology:Fossil fuelsHeating technologies that use fossil fuels are tried and tested, available worldwide and relatively inexpensive. However, due to socio-political discussions and climate policy goals, it is highly likely that such heating technologies will have to be replaced by CO2-neutral technologies in the medium term.Solar thermal energy / photovoltaics.As sensible as investing in a photovoltaic system may seem in order to reduce electricity costs %u2013 which remain largely constant over the course of a year %u2013 the situation is different when it comes to thermal energy. When it comes to concrete curing, thermal energy is mostly needed during the cooler half of the year, when little to no energy is available from solar or photovoltaic systems. Without a cost-effective way of storing heat and electricity, this option does not currently appear to be viable.Electricity / heat pumpsIn principle, electricity combined with a heat pump is a good way of generating thermal energy in a climate-neutral manner. However, the investment costs for an industrial heat pump are significantly higher than for fossil fuel heat generators and only pay for themselves over a long period of time. In addition, it must be checked locally whether a sufficient heat source is available, e.g. from geothermal energy or waste heat, as a heat pump does not generate energy itself, but uses electrical energy to provide a low-temperature heat source at a higher temperature level. The quality of the heat source is crucial for the efficiency of the heat pump.In summary, it can be said that none of the options mentioned can be strongly recommended for the active heating of curing chambers. Therefore, another option appears to be interesting, which allows for a more variable approach to determining the heating technology: The option of hot water generation.Hot water productionWater is not an energy source, but it is capable of transporting large amounts of heat and transferring it to a process by means of a heat exchanger. If your curing chamber is equipped with the appropriate heat exchangers and a hot water circuit, you can connect a single or a combination of different heat generation sources at one end. This means that a gas condensing boiler installed initially can be replaced later by a heat pump without having to dismantle the entire heating system.This heating technology, favoured by Rotho, is becoming increasingly popular for several reasons:%u2022 Deciding on a heating technology can be changed relatively easily at a later date. %u2022 Rotho offers customers the option of providing their own hot water supply. This allows customers to reduce the costs for heating technology. Another advantage is that the heating system can be maintained by a local supplier.%u2022 By installing heat exchangers in the individual circulation circuits of the Rotho ProAir recirculation system, a very uniform climate can be created in the curing chamber.