不同细度稻壳灰对混凝土强度及自收缩的影响

Effect of fineness of rice-husk ash on strength and autogenous shrinkage of concrete

研究4种细度的稻壳灰在5%~30%的掺量下对混凝土的强度和早期自收缩的影响.结果表明,混凝土的28d抗压强度与保证混凝土抗压强度比不小于100%的最大掺量均随稻壳灰的特征粒径D50的减小而增大;稻壳灰孔结构的吸水性可对混凝土的强度发展和早期自收缩产生影响,且D50越大影响越明显;D50在2.96~21.06μm时,稻壳灰可不同程度地抑制混凝土的早期自收缩,且其抑制程度随D50和掺量的增大而增大.

The effect of four kinds of fineness of rice-husk ash（RHA）with mixing amount of from 5%to30% on the compressive strength and autogenous shrinkage of the concrete was studied.The result showed that the compressive strength of concrete aged for 28 days and the maximum mixing amount which ensures the ratio of compressive strength is not less than 100%,would increase with the decrease of the characteristic particle size D50 of the RHA.The strength progression and early-age autogenous shrinkage of the concrete could be influenced due to the water absorption of the porous structure of the RHA,and the larger the D50 was,the more obvious the influences would be.The early-age autogenous shrinkage of the concrete could be restrained to some extent when the range of D50 was between 2.96 and 21.06μm,and as the D50 and mixing amount of RHA increased,the degree of restraint would increase as well.