Both models use a single electro-mechanical control system to ensure that the needle penetrates the mortar at a fixed speed. The needles have an appropriate shape to ensure a constant friction surface.
The single-needle model is used for testing cement paste (mortar without sand) and has a 5Kg load cell connected to the needle to measure the penetration force at a penetration speed of 3mm/hour over a maximum test time of 12 hours.
The 4-needle version is used for testing cement paste with sand and has a 3kN load cell connected to each needle to measure the penetration force at a penetration speed between 1.5mm/hour to 30mm/hour. Each needle has a pneumatic system to disengage it once a force of 3kN is reached. The four load cells measure the consistency in a single sample. Their average reading gives a better result than a single needle on sand mixtures due to consistency variations in the sample. This device is particularly useful for testing concrete spray used for tunnel lining.
This system enables a graph of the penetration force versus time to be captured and displayed on a computer screen. The setting time of the mortar can be predicted from the shape of this graph.
The manufacturer claims that this method of predicting the setting time of mortar is more accurate than the traditional Vicat method where a needle is repeatedly pushed into the setting mortar with a fixed force and setting is determined when the needle is not able to penetrate a pre-set distance. Several well-known European cement manufacturers and cement additive manufacturers are now using these penetrometers for this purpose.
These machines far exceed the accuracy in force measurement or control of penetration speed of existing manual penetrometers.
LBG is part of a long established Italian group of companies involved in the field of materials testing.
Hylec Controls | Test Equipment Suppliers and Integrators
Hylec Control was first established in 1979 and initially started operation as a developer and manufacturer of analogue control systems. These were specially customised hydraulic applications, using ...