常温与冻融条件下全轻纤维混凝土的性能比较

Performance comparisons on all-lightweight fiber reinforced concrete under ordinary temperatures and freeze-thaw cycles

为了探讨纤维对全轻混凝土分别在常温和冻融条件下的性能影响,采用强度增益比RXS分别表征不同种类及掺量纤维对不同强度的贡献率,以及对冻融指标中的质量损失ΔW和相对动弹模ΔP的影响。结果表明,虽然RXS均≥1,但对不同强度的影响不同,并以纤维混掺较单掺时好,而且对抗压、抗折强度提高幅度较大;轻骨料混凝土以ΔP下降速率较慢而表现为抗冻性能较好,但ΔW的损失速率则较普通要大,从而不能说明轻骨料混凝土的综合抗冻性能好;与不同混凝土的抗冻性能比较发现,混凝土的抗冻性能主要取决于抗压、抗折强度,亦即密实度;但轻骨料混凝土因骨料自身强度较低和多孔性质,从而导致全轻混凝土的密实度和强度较低,因此其抗冻性能并不显著。此外,抗冻性能也可间接反映混凝土的其他耐久性能。

Abstract： In order to study the influences of fibers on all-lightweight concrete （ALWC） under normal temperatures and freeze-thaw cycles, the ratio of gain to strength of anther strength（called RXS, named the ratio of the strength of fiber reinforced concrete from plain concrete correspondingly,X represents compressive strength（CS ）, splitting tensile strength（TS ） and bending strength （BS） respectively） is used to evaluate the contribution to strengths for different kinds of fibers and added amounts, and the mass losses ΔW and the relative dynamic elastic modulus Δp in the indexes of freeze-thaw.The results show the influences of fibers are different with strength different although the RXS ≥ 1, which is better when mixed by hybrid fibers than by single ones, and the contribution to CS and BS is larger.What the freeze-resistance is better usually means the rate of ΔP losses less, but the rate of ΔW losses is larger, so it is not the right saying that the freeze-resistance of LWC is better than normal concrete.It also shows the freeze-resistance of concrete depends on CS and BS, named the degree of density when compared with other kinds of concretes.The freeze-resistance of LWC is less because the strength of aggregate is lower and which is a property of the porous medium, so the strength and the density are lower.Again,the freeze-resistance can also indirectly reflect other durability of concrete.