It is used to measure the drying shrinkage of autoclaved portland cement and potential expansive reactivity of Cement aggregate combinations in mortar bars during storage on self-drying. The instrument consists of chanelled base over which two vertical pillars are fixed. An adjustable cross plate is at the top. A dial gauge, reading to 0.002 mm x 12 mm or 0.01 X 25mm is fixed to the top. The plunger end of the dial Gauge can be located up on a 6.5 mm. dia ball or other reference point cemented in the specimen. On the base there is a similar recessed seating in which can be placed a second ball or reference point in the specimen. Complete with a stainless steel standardiation bar with insulated grip and with 6.5mm dia ball mounted in the ends.