The present invention relates to a sizing composition in the form of a physical gel for glass strands which contains 0.1 to 5% by weight of at least one texturing agent chosen from xanthans, guars and succinoglycans, 2 to 8% by weight of at least one film-forming agent, 0.1 to 8% by weight of at least one compound chosen from plasticizing agents, surface-active agents and dispersing agents, 0.1 to 4% by weight of at least one coupling agent, and 0 to 6% by weight of at least one additive. Another subject-matter of the present invention is glass strands coated with the abovementioned sizing composition and the composite materials containing an organic or inorganic material reinforced with the said glass strands.