Abstract: A filler material for a road paving composition is described, the material having a low sensitivety to water and having fine gravel, pebbles and an organic binder selected from the group consisting of ashphalt, bitumen and tar, said filler material comprising at least one natural hydrated silicate selected from the group consisting of kaolinite, antigorite, sepiolite and palygorskite, said hydrated silicate having been subjected to a heat treatment at a temperature between 200.degree.C and 800.degree.C to irreversibly remove water of hydration to enhance porosity and ability to absorb bitumen, said filler material having a fineness at which at least 80% by weight will pass through a 74 micron screen, a porosity of at least 50% by volume and a swelling factor of not more than 3% in water after said organic binder has been absorbed therein.