养护措施和湿养护时间对掺与未掺矿渣混凝土性能的影响(英文)

EFFECT OF CURING METHODS AND WET CURING DURATION ON PROPERTIES OF PLAIN AND SLAG-CEMENT CONCRETE

研究了采用湿棉絮覆盖、喷养护剂、塑料薄膜密封3种养护措施对混凝土强度、收缩、中心温升、氯离子渗透性的影响,并通过不同龄期强度、氯离子渗透深度(5% NaCl溶液介质,质量分数)、钢筋腐蚀电位、加速腐蚀保护层开裂时间研究湿养护时间(1,7,14d和28d)对未掺和掺矿渣(等量取代水泥40%,质量分数)混凝土强度、抗渗性、护筋性的影响。结果表明:合适的养护措施能有效提高混凝土强度和抗渗性,降低水化温升和早期收缩。对未掺与掺矿渣的混凝土,更长的湿养护有助发展更高强度、耐久性和护筋性;而不充分养护导致混凝土较差的抗渗性和护筋性,该影响对掺矿渣混凝土尤为明显。7d湿养护对掺矿渣混凝土发展更高的潜在抗渗性是不够的。

Three curing methods were used for concrete curing with wet cotton mats, a curing agent and plastic film. The strength, shrinkage, central temperature and chloride permeability under various curing methods were studied. The effect of wet curing duration （1, 7, 14 and 28 d） on the strength, impermeability and corrosion resistance for protecting internal reinforcement of plain and slag-cement concrete （in which 40% （in mass） cement was replaced by blast furnace slag） was studied by experiments including strength, chloride penetration depth immersed in 5% （in mass） NaCl solution, half-cell potential and concrete cover cracking time in accelerated corrosion. The results show the proper curing methods can effectively increase the strength, reduce the central temperature due to hydration heat and the early shrinkage strain and improve the chloride impermeability. Longer wet curing duration is essential to achieve higher strength, durability and corrosion resistance characteristics while inadequate wet curing resulted in poorer chloride impermeability and corrosion resistance for both plain and slag cement concrete, but especially for slag cement concrete. The plain cement concrete is relatively more tolerant to inadequate curing. The higher potential chloride penetration resistance can not be activated later in the natural environment if wet curing was ceased on the 7th day.