生態(tài)鋼纖維混凝土彎曲韌性和斷裂性能

鄧宗才+王輝+劉巖

摘要：為掌握生態(tài)鋼纖維混凝土的彎曲韌性和斷裂性能，分別對摻率（體積分?jǐn)?shù)）為1.0%，1.7%，2.4%的2種異形生態(tài)鋼纖維混凝土和摻率為0.7%，1.3%的原生高強(qiáng)鋼纖維增強(qiáng)混凝土進(jìn)行了無切口梁四點(diǎn)彎曲韌性試驗(yàn)和切口梁三點(diǎn)彎曲斷裂試驗(yàn)。研究結(jié)果表明：生態(tài)鋼纖維摻率為1.0%時(shí)，無切口梁四點(diǎn)彎曲荷載-撓度曲線和切口梁三點(diǎn)彎曲荷載-撓度及荷載-切口張開位移曲線在達(dá)到峰值后都出現(xiàn)局部陡降，試件殘余強(qiáng)度較小，斷裂韌度值較低，纖維對改善混凝土彎曲韌性和斷裂性能的作用較??；當(dāng)生態(tài)鋼纖維摻率為1.7%時(shí)，混凝土彎曲韌性和斷裂性能均得到顯著提高，混凝土在變形達(dá)到15δult，p（δult，p為素混凝土峰值荷載對應(yīng)的撓度）或70Dult，p（Dult，p為素混凝土峰值荷載對應(yīng)的切口張開位移）水平時(shí)，依然具有較高的持荷能力和較好的韌性，波浪型生態(tài)鋼纖維混凝土斷裂能和斷裂韌度是素混凝土的27.59倍和8.35倍；生態(tài)鋼纖維摻率為2.4%時(shí)，混凝土彎曲韌性指標(biāo)、斷裂能和斷裂韌度進(jìn)一步增加；摻率為1.7%的生態(tài)鋼纖維混凝土增韌和抗斷裂效果與摻率為0.7%的原生高強(qiáng)鋼纖維混凝土相當(dāng)。

關(guān)鍵詞：生態(tài)鋼纖維混凝土；原生高強(qiáng)鋼纖維混凝土；彎曲韌性；斷裂性能；摻率

中圖分類號(hào)：TU502 文獻(xiàn)標(biāo)志碼：A

文章編號(hào)：1673-2049（2017）02-0111-08

Abstract：In order to grasp the flexural toughness and fracture property of ecological steel fiber reinforced concrete， four-point bending toughness test for beam and three-point bending fracture test for notched beam were carried out with different volume fractions of ecological steel fibers 1.0%， 1.7%，2.4% and different volume fractions of native high strength steel fibers 0.7%， 1.3%. The results show that when the volume fraction of ecological steel fiber is 1.0%， four-point bending load-deflection curves of beam and three-point bending load-deflection curves and load-crack mouth opening displacement curves of notched beam are partial steep drop after the peak point， residual strength and fracture toughness are low.Ecological steel fibers have less improvement on toughness and fracture properties. When the volume fraction of ecological steel fiber is 1.7%， the flexural toughness and fracture property of concrete are greatly improved，concretes still have high toughness when the deformation is 15δult，p（δult，p is deflection corresponding to peak load of plain concrete） and 70Dult，p（Dult，p is peak crack mouth opening displacement corresponding to peak load of plain concrete）， fracture energy and fracture toughness of wavy ecological steel fiber concrete are 27.59 times and 8.35 times to plain concrete. When the volume fraction of ecological steel fiber is 2.4%， flexural toughness index， fracture energy and fracture toughness further increase. The toughening and fracture resistance effects of 1.7% volume fraction of ecological steel fiber are almost close to those of 0.7% native high strength steel fiber.

Key words：ecological steel fiber reinforced concrete； native high strength steel fiber reinforced concrete； flexural toughness； fracture toughness； volume fraction