Samenvatting

A remote sensor network can be used for a great variety of purposes e.g. in our case, to monitor the compressive strength of concrete during its curing process and improve the concrete treatment [10, 18].
The method of weighted maturity through in-site temperature readings is valued highly by both academic as well as professional experts. Primarily for the non-destructive character, the accuracy, the ability to control the process with real-time measurements and simplicity as there is no need for (on-site) stored and unrepresentative sampling cubes, highly specialist workers, and equipment. [18]
Our end-devices (equipped with a temperature sensor) can be embedded into concrete and take temperature samples from within. The data samples from the end-devices need to travel through several nodes, over different interfaces and protocols and are transformed many times before reaching its destination, the server (see figure 1). The WSN uses ZigBee® for its energy efficient features. A sensor device can work on a single button cell for several weeks, months, or even years, depending on the application. It can collect data samples and from these samples, assemble a message, called a sequence. Such a sequence stored locally and sent to the coordinator if it is reachable. The data might travel through several ZigBee® routers if the coordinator is out of range of the end-device.
The ZigBee® coordinator transfers the sequence over RS-232 to the GPRS module for RS-232 is widely used, reliable and supported by J2ME™, which runs on the GPRS module. The GPRS module keeps track
of the sequence numbers and will request missing ones.
The GPRS module makes it possible to have a wireless sensor network at one location and the datacollecting server at another, as long as the GPRS module is in range of the GPRS network (and has sufficient credit). The server can build a model and graphs that as a result can be showed to the costumer at any location with an internet connection. From these results, the client can see the progress of the curing process and can react on it if necessary.