关键词: 石膏集料;混凝土;硫酸盐侵蚀;变形;强度

Abstract: The effect of the content of gypsum-bearing crushed rocks and sands in aggregates on the deformation , compressive strength , speed of ultrasonic wave of concretes were investigated . The microstructures of the concretes were examined with SEM .It was found that gypsum used as coarse aggregate has little effect on deformation , compressive strength and speed of ultrasonic wave of concretes when the SO3 content of aggregates derived from crushed gypsum is less than 1.5％by weight.Significant loss of strength would occur if the SO3 content of aggregates supplied by crushed gypsum exceeds 3％by weight.When SO3 content of the aggregates derived from sandy gypsum is more than 1.5％, concretes expand.As a result, the strength of concretes decrease significantly after 150 d.Massive ettringite crystals formed near gypsum particles cause the cement pastes to expand or even crack .

Key words: gypsum aggregate;concrete;sulfates attack;deformation;strength