The development of heave and swelling pressure in the natural calcareous expansive soils in the Eastern Province of Saudi Arabia causes major damage to structures constructed on or in them. The behaviour of expansive soil depends on the predominant type of clay minerals present, the cementing agents that bind these clay minerals and other physical and chemical properties. This paper presents the problems and the geotechnical and physicochemical properties of the calcareous expansive soil deposits in the Eastern Province of Saudi Arabia. X-ray, thermal and chemical analyses and scanning electron microscopy were used to estimate the type and quantity of clay and non-clay minerals and fabric of the investigated soil. The swelling potential was determined using a conventional oedometer test. A field test conducted for measurement of heave was compared with heave estimated from laboratory- tests, Results showed that the investigated soil had moderate to very high swelling potential and the heave estimated from the suction method was very close to the value measured from the field test.