养护方式和龄期对碾压混凝土强度影响的研究

Study on Effect of Curing Methods and Age on Strength of Roller Compacted Concrete

碾压混凝土属于超干硬性混凝土,具有水泥用量少、收缩变形小,力学强度高、施工速度快、养护周期短等特点。然而,其多用在水利大坝和低等级路面,作为隧道基层的研究较少。通过结合工程实际,研究不同龄期标准养护、室外保湿养护、各面刷乳化沥青养护和室外不养护等不同条件下的隧道基层碾压混凝土试件抗折、抗压强度,结果表明:标养条件养护效果最好,现场洒水保湿养护次之,刷乳化沥青养护和不养护效果相近甚至更差;不同养护条件试件,3 d抗折抗压强度均达到28 d强度的65%,7 d抗折抗压强度达到28 d强度的80%,180 d试件强度较28 d有所增长,但较早期增长幅度明显变小,故加强保温保湿养护对碾压混凝土早期强度的发展意义重大。

Roller compacted concrete(RCC)belongs to ultra-dry concrete,which has the characteristics of low cement consumption,small shrinkage deformation,high mechanical strength,fast construction speed and short curing period.However,it was mostly used in water conservancy dams and low-grade pavements,less used as tunnel base.Through combination with the engineering practice,the flexural and compressive strength of RCC specimens was studied with different curing ages and curing methods.The different curing methods were standard curing,outdoor wet curing,the surface brushing emulsified asphalt curing and outdoor without curing.The results showed that standard curing method worked the best,outdoor wet curing method was the second,the effect of brushing emulsified asphalt curing was similar to without curing or even worse.The flexural and compressive strength of specimens under different curing conditions reached 65%of 28 d strength in 3 d and 80%of 28 d strength in 7 d.The strength of specimens in 180 d increased compared with that in 28 d,but the growth rate was obviously smaller than that in early stage.Therefore,it is of great significance to strengthen heat preservation and moisture curing for the development of early strength of RCC.