摘(zhai) 要(yao)

纖維(wei)素纖維(wei)廣泛應用在SMA、OGFC等(deng)開(kai)級(ji)配、間斷級(ji)配型瀝(li)青混合料中。本(ben)文(wen)主要論述絮狀和粒狀兩種纖維素纖維的(de)組成(cheng)成(cheng)分、作(zuo)用(yong)機理、類型來(lai)源及加工工藝(yi)等(deng)方面(mian)內(nei)容。介紹了(le)纖維素纖維耐熱(re)性(xing)(xing)、松方密度等(deng)性(xing)(xing)能(neng)參數對纖維性(xing)(xing)能(neng)的(de)影(ying)響(xiang)及試驗方法。研究(jiu)成(cheng)果可為國內(nei)公路工程實際應用(yong)提供參考意見。

關鍵詞(ci)

       絮(xu)狀纖維素纖維 | 粒狀纖維素(su)纖維 | 耐熱性 ;| 來源(yuan)識別(bie) | 性能(neng)參(can)數(shu)

通常將長徑比(bi)大且有一定(ding)柔韌(ren)性(xing)和強(qiang)(qiang)度的纖(xian)(xian)(xian)細(xi)物(wu)(wu)質稱為纖(xian)(xian)(xian)維(wei)(wei)(wei)，其(qi)具有彈性(xing)模(mo)量大，塑(su)性(xing)變形(xing)小，強(qiang)(qiang)度高等特點。纖(xian)(xian)(xian)維(wei)(wei)(wei)根據其(qi)生產條件可(ke)以分為天(tian)然(ran)(ran)(ran)纖(xian)(xian)(xian)維(wei)(wei)(wei)和化學纖(xian)(xian)(xian)維(wei)(wei)(wei)。天(tian)然(ran)(ran)(ran)纖(xian)(xian)(xian)維(wei)(wei)(wei)根據纖(xian)(xian)(xian)維(wei)(wei)(wei)來源(yuan)可(ke)分為植(zhi)物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)、動物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)及(ji)礦(kuang)物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)。化學纖(xian)(xian)(xian)維(wei)(wei)(wei)可(ke)分為人(ren)造纖(xian)(xian)(xian)維(wei)(wei)(wei)、合(he)成纖(xian)(xian)(xian)維(wei)(wei)(wei)和無(wu)機纖(xian)(xian)(xian)維(wei)(wei)(wei)。目前我國公(gong)路工(gong)程常用植(zhi)物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)，如針葉(xie)木纖(xian)(xian)(xian)維(wei)(wei)(wei)。動物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)和天(tian)然(ran)(ran)(ran)礦(kuang)物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)很少應用。其(qi)中天(tian)然(ran)(ran)(ran)礦(kuang)物(wu)(wu)纖(xian)(xian)(xian)維(wei)(wei)(wei)，主要是石(shi)棉纖(xian)(xian)(xian)維(wei)(wei)(wei)會損害施工(gong)人(ren)員的身體健(jian)康并造成環境污染，已(yi)靜止應用到(dao)公(gong)路工(gong)程當(dang)中。

纖維素纖維成(cheng)分及作用機理

《公(gong)路瀝青路面(mian)施工(gong)技(ji)術規范》(JTGF40-2004)、《公路瀝青碼(ma)蹄脂(zhi)碎石(shi)路面技術指(zhi)南》(SHCF40-01-2002)、《瀝青路面用木(mu)質素纖(xian)(xian)維(wei)》(JT/T533-2004)將(jiang)纖(xian)(xian)維(wei)定義為(wei)(wei)木(mu)質素纖(xian)(xian)維(wei)(plantfiber)，屬于(yu)有(you)機(ji)纖(xian)(xian)維(wei)，特指(zhi)針葉木(mu)材纖(xian)(xian)維(wei)(coniferoustreefiber或coniferfiber)。在(zai)歐(ou)美、澳大利(li)亞等國家稱為(wei)(wei)纖(xian)(xian)維(wei)素纖(xian)(xian)維(wei)(cellulosefi-bers)，屬于(yu)植物纖(xian)(xian)維(wei)。根據《中(zhong)(zhong)國土木(mu)工(gong)程(cheng)建筑百(bai)科辭典》(工(gong)程(cheng)材料(liao)(liao)上)中(zhong)(zhong):纖(xian)(xian)維(wei)素纖(xian)(xian)維(wei)為(wei)(wei)某些植物的桿與韌皮經加工(gong)后制得(de)的纖(xian)(xian)維(wei)，通(tong)常以針葉樹(shu)、闊葉樹(shu)作(zuo)原料(liao)(liao)，直徑(jing)為(wei)(wei)20~120μm，長度(du)為(wei)(wei)0.5~5mm，抗拉強度(du)為(wei)(wei)300~800MPa，彈性模量為(wei)(wei)10~30GPa。

植(zhi)物(wu)纖(xian)(xian)維(wei)(wei)是由纖(xian)(xian)維(wei)(wei)素(su)(su)、半纖(xian)(xian)維(wei)(wei)素(su)(su)、木質素(su)(su)和其(qi)他少量(liang)雜質組(zu)成(cheng)，由于植(zhi)物(wu)纖(xian)(xian)維(wei)(wei)的主(zhu)要化(hua)學成(cheng)分是纖(xian)(xian)維(wei)(wei)素(su)(su)，故植(zhi)物(wu)纖(xian)(xian)維(wei)(wei)可稱為纖(xian)(xian)維(wei)(wei)素(su)(su)纖(xian)(xian)維(wei)(wei)。一(yi)般木材纖(xian)(xian)維(wei)(wei)中，纖(xian)(xian)維(wei)(wei)素(su)(su)占40%~50%，還(huan)有10%~30%的(de)半(ban)纖(xian)維(wei)素和20%~30%的(de)木(mu)質(zhi)素。纖(xian)維(wei)素纖(xian)維(wei)原(yuan)材料豐富，價格低廉，是現(xian)階(jie)段纖(xian)維(wei)穩定劑的(de)主(zhu)流方向，應(ying)用較(jiao)為廣(guang)泛。

纖維(wei)(wei)素纖維(wei)(wei)的類型(xing)和來源

纖維素纖維分類

根(gen)據造紙行業植物纖(xian)維分類(lei)，可(ke)將纖(xian)維素纖(xian)維分為(wei)以下6類(lei):(1)針葉(xie)樹木(mu)材:如(ru)(ru)(ru)落葉(xie)松(song)、紅(hong)松(song)、馬尾松(song)、云南(nan)松(song)、樟子松(song)等(deng);(2)闊葉(xie)樹木(mu)材，如(ru)(ru)(ru)楊木(mu)、樺(hua)木(mu)、桉(an)木(mu)等(deng);(3)草(cao)類(lei)植物:如(ru)(ru)(ru)蘆葦、竹子、芒稈、麥草(cao)、稻草(cao)、龍須(xu)草(cao)、高(gao)粱桿(gan)、蔗渣等(deng);(4)韌皮(pi)纖維(wei)類(lei):如(ru)(ru)(ru)亞(ya)麻(ma)、黃麻(ma)、洋(yang)麻(ma)、檀(tan)樹皮(pi)、桑皮(pi)、棉稈皮(pi)等(deng);(5)種毛纖維(wei)類(lei):如(ru)(ru)(ru)棉花(hua)、棉短絨、棉破(po)布;(6)廢紙(zhi)纖維(wei)類(lei):破(po)殘紙(zhi)、舊紙(zhi)板(ban)等(deng)。

根據我(wo)國瀝青混合(he)料的應用來看，可將纖維素纖維分(fen)為絮(xu)狀和粒狀兩類見圖1。粒(li)狀(zhuang)纖(xian)(xian)(xian)維(wei)(wei)(wei)素纖(xian)(xian)(xian)維(wei)(wei)(wei)是(shi)采(cai)用瀝(li)青(qing)(qing)或蠟做為造(zao)粒(li)劑，由(you)純絮狀(zhuang)纖(xian)(xian)(xian)維(wei)(wei)(wei)經物(wu)理(li)作用制(zhi)成(cheng)的(de)(de)(de)高質(zhi)(zhi)量(liang)(liang)(liang)高純度的(de)(de)(de)纖(xian)(xian)(xian)維(wei)(wei)(wei)。在(zai)瀝(li)青(qing)(qing)混(hun)合(he)料(liao)拌和過程中纖(xian)(xian)(xian)維(wei)(wei)(wei)表面的(de)(de)(de)瀝(li)青(qing)(qing)涂層受熱易于融化，其中的(de)(de)(de)纖(xian)(xian)(xian)維(wei)(wei)(wei)素纖(xian)(xian)(xian)維(wei)(wei)(wei)可以(yi)迅速分散在(zai)混(hun)合(he)料(liao)中并吸(xi)附瀝(li)青(qing)(qing)，達到穩定瀝(li)青(qing)(qing)混(hun)合(he)料(liao)的(de)(de)(de)效果(guo)。主要應(ying)用在(zai)SMA、OGFC等(deng)開級(ji)配、間斷(duan)級(ji)配型(xing)瀝(li)青(qing)(qing)混(hun)合(he)料(liao)中，能起到持油、減少析漏(lou)等(deng)作用。我(wo)們通常(chang)將其稱為纖(xian)(xian)(xian)維(wei)(wei)(wei)穩定劑(fiberstabilizer)。其推薦最(zui)佳(jia)用量(liang)(liang)(liang)是(shi)瀝(li)青(qing)(qing)混(hun)合(he)料(liao)質(zhi)(zhi)量(liang)(liang)(liang)的(de)(de)(de)0.3%~0.4%。但工(gong)程中的(de)(de)(de)實際用量(liang)(liang)(liang)應(ying)考(kao)慮其它材料(liao)的(de)(de)(de)選用、用量(liang)(liang)(liang)、施工(gong)工(gong)藝(yi)及(ji)天氣(qi)環(huan)境等(deng)因素，根(gen)據試驗結果(guo)再另行確定。

纖維(wei)素纖維(wei)來源

美(mei)國(guo)、加拿(na)大、德國(guo)及法國(guo)等國(guo)家使用(yong)的纖(xian)(xian)維(wei)素(su)(su)纖(xian)(xian)維(wei)最常見來(lai)(lai)源(yuan)于木材植(zhi)物，也有一些來(lai)(lai)源(yuan)于回收的報紙(zhi)。在歐美(mei)國(guo)家特別是北美(mei)針(zhen)葉木材資源(yuan)非常豐富。而我(wo)國(guo)瀝(li)青路(lu)面用(yong)纖(xian)(xian)維(wei)素(su)(su)纖(xian)(xian)維(wei)來(lai)(lai)源(yuan)較為(wei)復(fu)雜，生產工藝也不盡相同。我(wo)國(guo)部分(fen)(fen)纖(xian)(xian)維(wei)素(su)(su)纖(xian)(xian)維(wei)來(lai)(lai)源(yuan)為(wei)針(zhen)葉木等木材，部分(fen)(fen)來(lai)(lai)源(yuan)于廢報紙(zhi)，部分(fen)(fen)甚至來(lai)(lai)源(yuan)于破棉布，因此我(wo)國(guo)纖(xian)(xian)維(wei)素(su)(su)纖(xian)(xian)維(wei)質量(liang)差(cha)異較大。

針葉(xie)木漿纖(xian)維，原纖(xian)維長度為2.56~4.08mm，寬度為(wei)(wei)40.9~54.9μm，組(zu)織結(jie)構(gou)(gou)嚴密且雜細(xi)(xi)胞含(han)量(liang)少(shao)。化學漿(jiang)料中的(de)雜細(xi)(xi)胞多在洗滌(di)時流失(shi)，纖(xian)維(wei)質(zhi)量(liang)好(hao)，木(mu)素(su)含(han)量(liang)達到(dao)25%-35%，多戊糖(tang)含(han)量(liang)低(di)，纖(xian)維(wei)不(bu)易吸水潤漲(zhang)。闊(kuo)葉(xie)(xie)木(mu)纖(xian)維(wei)的(de)長度約(yue)為(wei)(wei)1mm，寬度為(wei)(wei)8~16μm，組(zu)織結(jie)構(gou)(gou)更加(jia)緊密，雜細(xi)(xi)胞較(jiao)多，木(mu)素(su)含(han)量(liang)較(jiao)針(zhen)葉(xie)(xie)木(mu)低(di)，一般為(wei)(wei)20%~24%，多戊糖(tang)含(han)量(liang)為(wei)(wei)21%-24%，易吸水潤漲(zhang)。木(mu)材纖(xian)維(wei)的(de)強度高、耐熱性好(hao)，其(qi)應(ying)用性能最佳，特別是針(zhen)葉(xie)(xie)木(mu)材纖(xian)維(wei)被(bei)廣(guang)泛的(de)應(ying)用到(dao)公路工程當(dang)中。而(er)棉花(hua)等(deng)破布纖(xian)維(wei)，秸稈纖(xian)維(wei)等(deng)耐熱性較(jiao)差，不(bu)宜應(ying)用到(dao)瀝(li)青混合料中。但我國的(de)針(zhen)葉(xie)(xie)木(mu)材資源(yuan)不(bu)足(zu)，完全采用原木(mu)材纖(xian)維(wei)不(bu)現實，也(ye)可采用以針(zhen)葉木材(cai)或闊葉木材(cai)為(wei)主(zhu)的回收報紙(zhi)等廢紙(zhi)材(cai)料。

纖維素纖維加(jia)工工藝(yi)

纖(xian)(xian)(xian)(xian)維(wei)(wei)素(su)(su)纖(xian)(xian)(xian)(xian)維(wei)(wei)按(an)照加工工藝可分(fen)為(wei)機(ji)械(xie)纖(xian)(xian)(xian)(xian)維(wei)(wei)和(he)(he)(he)化(hua)學纖(xian)(xian)(xian)(xian)維(wei)(wei)。機(ji)械(xie)纖(xian)(xian)(xian)(xian)維(wei)(wei)，利用(yong)機(ji)械(xie)方(fang)法(fa)(fa)磨解(jie)纖(xian)(xian)(xian)(xian)維(wei)(wei)原(yuan)料所制成的(de)纖(xian)(xian)(xian)(xian)維(wei)(wei)，分(fen)為(wei)白(bai)色(se)(se)磨木纖(xian)(xian)(xian)(xian)維(wei)(wei)和(he)(he)(he)褐色(se)(se)磨木纖(xian)(xian)(xian)(xian)維(wei)(wei)。機(ji)械(xie)纖(xian)(xian)(xian)(xian)維(wei)(wei)具有生產過程較簡單(dan)、成本低、得率高(gao)、污(wu)染小的(de)特(te)點(dian)，但(dan)雜(za)質含(han)量較高(gao)且儲存穩定性差。化(hua)學纖(xian)(xian)(xian)(xian)維(wei)(wei)是以化(hua)學方(fang)法(fa)(fa)離解(jie)植物纖(xian)(xian)(xian)(xian)維(wei)(wei)而得的(de)纖(xian)(xian)(xian)(xian)維(wei)(wei)。根據所用(yong)方(fang)法(fa)(fa)可分(fen)為(wei)堿法(fa)(fa)、硫(liu)酸(suan)鹽(yan)(yan)法(fa)(fa)、亞(ya)硫(liu)酸(suan)鹽(yan)(yan)法(fa)(fa)、中性亞(ya)硫(liu)酸(suan)鹽(yan)(yan)法(fa)(fa)和(he)(he)(he)氯化(hua)法(fa)(fa)等。目(mu)前我國瀝青混(hun)合料用(yong)絮(xu)狀(zhuang)纖(xian)(xian)(xian)(xian)維(wei)(wei)素(su)(su)纖(xian)(xian)(xian)(xian)維(wei)(wei)中同時含(han)有機(ji)械(xie)纖(xian)(xian)(xian)(xian)維(wei)(wei)和(he)(he)(he)化(hua)學纖(xian)(xian)(xian)(xian)維(wei)(wei)。

纖維(wei)(wei)素纖維(wei)(wei)性(xing)能參數及試(shi)驗方法

纖維尺寸

纖(xian)維的(de)(de)(de)(de)長(chang)度和(he)直(zhi)徑是纖(xian)維的(de)(de)(de)(de)重(zhong)要形(xing)態(tai)參數，對瀝青混合(he)料性能(neng)(neng)(neng)影響(xiang)較大。纖(xian)維增(zeng)強效(xiao)(xiao)果(guo)主要取決于單(dan)位質量的(de)(de)(de)(de)有效(xiao)(xiao)纖(xian)維根數，直(zhi)徑越(yue)小(xiao)長(chang)度越(yue)長(chang)的(de)(de)(de)(de)纖(xian)維增(zeng)強效(xiao)(xiao)果(guo)越(yue)明(ming)顯。在(zai)相同的(de)(de)(de)(de)增(zeng)強效(xiao)(xiao)果(guo)下，直(zhi)徑越(yue)小(xiao)，纖(xian)維摻量越(yue)低能(neng)(neng)(neng)很(hen)好的(de)(de)(de)(de)降低工(gong)(gong)程造價。但(dan)是直(zhi)徑過小(xiao)，纖(xian)維容易斷(duan)裂(lie)。纖(xian)維長(chang)度越(yue)長(chang)，瀝青混合(he)料的(de)(de)(de)(de)抗拉、抗裂(lie)、抗折及抗高溫性能(neng)(neng)(neng)越(yue)明(ming)顯，但(dan)長(chang)度過長(chang)會增(zeng)加(jia)纖(xian)維絮聚(ju)的(de)(de)(de)(de)危險，從而降低施工(gong)(gong)拌和(he)的(de)(de)(de)(de)均勻性，影響(xiang)施工(gong)(gong)性能(neng)(neng)(neng);纖(xian)維長度過短(duan)則增粘作用有限，持油吸附能力變差(cha)。

(1)纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)長(chang)(chang)度(du):絮(xu)狀纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)長(chang)(chang)度(du)不均一且纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)難(nan)以分(fen)離，長(chang)(chang)度(du)測(ce)定較為復雜。現有(you)的標準中對纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)素(su)纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)的長(chang)(chang)度(du)測(ce)定方法(fa)規定不明確，本(ben)文通過試驗確定采用(yong)(yong)顯(xian)微(wei)鏡(jing)圖(tu)像(xiang)分(fen)析(xi)法(fa)進行(xing)測(ce)定。將纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)用(yong)(yong)赫茲(zi)伯格(Herzberg)染色(se)劑染色(se)后用(yong)(yong)顯(xian)微(wei)鏡(jing)放大，把纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)圖(tu)像(xiang)信(xin)號轉(zhuan)變為電子數碼信(xin)號輸(shu)送(song)到計(ji)(ji)算(suan)機(ji)(ji)。用(yong)(yong)鼠標在(zai)顯(xian)示屏上(shang)沿纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)走(zou)向將纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)細分(fen)成多(duo)段(duan)直線進行(xing)測(ce)量(liang)如圖(tu)2，計(ji)(ji)算(suan)機(ji)(ji)自動跟蹤所測(ce)纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)，描繪纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)骨架結構(gou)，自動計(ji)(ji)算(suan)纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)實際長(chang)(chang)度(du)。絮(xu)狀纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)中每(mei)根纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)的長(chang)(chang)度(du)不同，須統計(ji)(ji)多(duo)條纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)的長(chang)(chang)度(du)計(ji)(ji)算(suan)其平均值。絮(xu)狀纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)素(su)纖(xian)(xian)(xian)(xian)維(wei)(wei)(wei)(wei)最大長(chang)(chang)度(du)不大于6mm。

(2)纖(xian)維(wei)直(zhi)(zhi)徑纖(xian)維(wei)直(zhi)(zhi)徑為(wei)μm級，絮狀纖(xian)維(wei)需用(yong)圖(tu)像(xiang)分(fen)(fen)析法測量(liang)纖(xian)維(wei)直(zhi)(zhi)徑。將橫(heng)向切斷后的纖(xian)維(wei)用(yong)樹(shu)脂(zhi)包裹后垂直(zhi)(zhi)放在載玻片上，放大400倍拍攝靜態圖(tu)片，用(yong)鼠標在顯示(shi)屏(ping)上點(dian)擊單根纖(xian)維(wei)縱側(ce)面兩個邊(bian)緣(yuan)點(dian)，計算(suan)機顯示(shi)距(ju)離即為(wei)纖(xian)維(wei)直(zhi)(zhi)徑。觀察(cha)足夠數(shu)量(liang)的纖(xian)維(wei)，計算(suan)算(suan)術平均值作(zuo)為(wei)纖(xian)維(wei)的平均直(zhi)(zhi)徑。粒狀纖(xian)維(wei)直(zhi)(zhi)徑一般分(fen)(fen)為(wei)4.5mm及6.5mm兩種規格(ge)。

篩分

通過篩分試驗(yan)確定纖(xian)(xian)維(wei)在(zai)某一(yi)篩孔的(de)通過率來間(jian)接評價纖(xian)(xian)維(wei)尺寸的(de)分布情況。對于公路工程用纖(xian)(xian)維(wei)篩分，參照美國(guo)NAPA、NCAT、AASHTO等標準(zhun)采用(yong)沖氣篩分析(xi)方(fang)法。此方(fang)法簡(jian)便(bian)快捷，可用(yong)于(yu)纖(xian)維質量評(ping)定(ding)，也適用(yong)于(yu)纖(xian)維生(sheng)產(chan)過(guo)程中質量控制。絮狀纖(xian)維可采用(yong)德(de)國Alpine氣分篩200LS-N型，在2500~3500Pa、10min篩分條件(jian)下比較0.15mm通過(guo)率。粒狀纖(xian)維可對原纖(xian)維及(ji)磨損后(hou)纖(xian)維分別測(ce)定(ding)4mm及(ji)2.8mm通過(guo)率。

灰分(fen)含量

纖維制造過程中通過噴涂(tu)耐高(gao)溫(wen)涂(tu)覆(fu)材(cai)料(liao)(liao)(liao)來保(bao)護纖維與(yu)集(ji)料(liao)(liao)(liao)拌和時(shi)不被高(gao)溫(wen)破壞(huai)。涂(tu)覆(fu)材(cai)料(liao)(liao)(liao)一(yi)般為(wei)高(gao)嶺土(tu)、碳酸鈣、硅藻土(tu)、提純的(de)膨脹土(tu)等無機材(cai)料(liao)(liao)(liao)。纖維經高(gao)溫(wen)燃燒后剩下的(de)部分稱為(wei)灰分，即(ji)為(wei)耐高(gao)溫(wen)的(de)涂(tu)覆(fu)材(cai)料(liao)(liao)(liao)。涂(tu)覆(fu)材(cai)料(liao)(liao)(liao)過少，不足以(yi)保(bao)護纖維素(su)纖維;涂覆材料(liao)過(guo)多，會妨礙纖(xian)維的(de)持油效果(guo)。因此(ci)纖(xian)維經高(gao)(gao)溫(wen)燃燒剩下的(de)灰(hui)分(fen)(fen)，必須控(kong)制(zhi)在(18±5)%的(de)范圍內。我(wo)國通(tong)常采(cai)用敞(chang)開(kai)式(shi)高(gao)(gao)溫(wen)爐(lu)進(jin)行(xing)試(shi)驗，人為進(jin)行(xing)溫(wen)度控(kong)制(zhi)，燃燒過(guo)程中不(bu)斷攪拌(ban)使得(de)纖(xian)維充(chong)分(fen)(fen)燃燒。但由于(yu)纖(xian)維中的(de)灰(hui)分(fen)(fen)在高(gao)(gao)溫(wen)條件下與氧(yang)氣(qi)發生(sheng)化學反應(ying)，使得(de)敞(chang)開(kai)式(shi)高(gao)(gao)溫(wen)爐(lu)測得(de)的(de)灰(hui)分(fen)(fen)含量大于(yu)封閉式(shi)灰(hui)分(fen)(fen)測試(shi)結果(guo)。為了確保(bao)試(shi)驗結果(guo)的(de)一致性，同時確保(bao)試(shi)驗安(an)全(quan)，降(jiang)低勞動強度，本文(wen)推薦采(cai)用封閉式(shi)高(gao)(gao)溫(wen)爐(lu)進(jin)行(xing)試(shi)驗。對(dui)于(yu)粒狀纖(xian)維素纖(xian)維，需要(yao)打散之后(hou)進(jin)行(xing)測定(ding)，有利(li)于(yu)纖(xian)維的(de)充(chong)分(fen)(fen)燃燒。

含水率(lv)

纖維(wei)暴露在空(kong)氣中不斷吸水(shui)，隨著水(shui)分(fen)的(de)(de)增加，纖維(wei)容易結(jie)團。含水(shui)率(lv)高的(de)(de)纖維(wei)在混合(he)料(liao)拌合(he)過程中不易分(fen)散，影(ying)響混合(he)料(liao)的(de)(de)均勻性，甚至(zhi)引起瀝青(qing)混合(he)料(liao)析漏。同時還影(ying)響纖維(wei)與瀝青(qing)、集料(liao)的(de)(de)粘附性。根據我國(guo)工程習慣，推薦采用(yong)105℃±5℃條件下烘(hong)干兩小時測定(ding)纖(xian)維(wei)的(de)含水(shui)率。纖(xian)維(wei)含水(shui)率要求不(bu)大于5%。

吸油(you)率

吸(xi)油率可用來評價纖維(wei)吸(xi)收、吸(xi)附(fu)瀝青(qing)的能力，也可間接反(fan)映纖維(wei)的尺寸分布。吸(xi)油率越大，纖維(wei)整體偏(pian)細;反之(zhi)，纖(xian)維(wei)(wei)(wei)整體偏粗。目前我國公路工程中(zhong)主要按(an)照《公路瀝(li)青(qing)路面施工技術(shu)規(gui)范》(JTGF40-2004)進行絮狀纖(xian)維(wei)(wei)(wei)素(su)纖(xian)維(wei)(wei)(wei)吸油率測定。纖(xian)維(wei)(wei)(wei)的(de)吸油率不宜過大，否則會吸收過多的(de)自由(you)瀝(li)青(qing)，不經濟。因此推(tui)薦絮狀纖(xian)維(wei)(wei)(wei)素(su)纖(xian)維(wei)(wei)(wei)吸油率為纖(xian)維(wei)(wei)(wei)質量的(de)5~8倍。

目前我國很多(duo)工程上對(dui)粒狀纖(xian)維也參照絮狀纖(xian)維進行評價，要求打散后吸油率不小(xiao)于5，這是不(bu)合(he)理的(de)(de)。由于(yu)粒(li)狀纖(xian)(xian)維(wei)表面及(ji)內(nei)部已(yi)經吸(xi)附部分瀝青，降低了纖(xian)(xian)維(wei)進一步吸(xi)收煤(mei)油的(de)(de)能力，且粒(li)狀纖(xian)(xian)維(wei)的(de)(de)吸(xi)油率(lv)還受結(jie)合(he)料類型及(ji)摻量的(de)(de)影響，即(ji)使打散(san)后(hou)測定(ding)也并(bing)不(bu)準(zhun)確。故(gu)粒(li)狀纖(xian)(xian)維(wei)素纖(xian)(xian)維(wei)測定(ding)其(qi)(qi)吸(xi)油率(lv)應(ying)對(dui)萃取結(jie)合(he)料之后(hou)的(de)(de)絮(xu)狀纖(xian)(xian)維(wei)進行測定(ding)。一般采用甲苯(ben)等溶劑加熱至220℃高溫萃取，不(bu)得將(jiang)粒(li)狀纖(xian)(xian)維(wei)打散(san)后(hou)萃取。其(qi)(qi)吸(xi)油率(lv)應(ying)按照纖(xian)(xian)維(wei)質量的(de)(de)4-7倍進行控制。粒(li)狀纖(xian)(xian)維(wei)由于(yu)其(qi)(qi)穩(wen)定(ding)的(de)(de)吸(xi)油率(lv)，攤鋪碾壓成型后(hou)的(de)(de)路面基本(ben)上(shang)呈黑亮色(se)，而且整個過程路面顏色(se)保持一致。

耐熱性

耐(nai)熱(re)性用來(lai)評價(jia)纖(xian)維在拌(ban)和時受集料(liao)(liao)高溫影響而物理性能(neng)降低的情(qing)況。纖(xian)維在拌(ban)合過(guo)程中受集料(liao)(liao)的切(qie)割變短，在高溫下燃(ran)燒脆(cui)斷，大(da)大(da)降低了纖(xian)維的效果。耐(nai)熱(re)性試驗前應先(xian)將試樣干燥(zao)處理(否則(ze)加(jia)熱(re)過程中水分(fen)的(de)(de)揮發(fa)也一并計入質(zhi)量(liang)損(sun)失，結果計算不(bu)合(he)理)，在210℃的(de)(de)條件下加(jia)熱(re)兩小(xiao)時，測試(shi)其質(zhi)量(liang)損(sun)失[5]。通過測試(shi)大(da)量(liang)典型纖(xian)維(wei)發(fa)現，幾(ji)乎所有(you)的(de)(de)纖(xian)維(wei)加(jia)熱(re)前后都有(you)明顯的(de)(de)顏色變化，體積變化肉眼很難觀察。因此，可不(bu)將顏色、體積做為評價(jia)指標。纖(xian)維(wei)的(de)(de)耐熱(re)性應不(bu)大(da)于6%。

纖(xian)維來源(yuan)識別

目前國(guo)內市場(chang)纖維(wei)(wei)(wei)來源混亂，產品參差不齊，部分纖維(wei)(wei)(wei)素纖維(wei)(wei)(wei)中摻加破布(bu)纖維(wei)(wei)(wei)，耐熱性較(jiao)差，施工過程中容易燃燒。可通過顯微鏡法參考(kao)《紡織纖維(wei)(wei)(wei)鑒別試驗方法第(di)3部分顯(xian)微鏡法》(FZT01057.3-2007)進(jin)行纖(xian)維來源識(shi)別見(jian)圖(tu)3。

針葉木纖(xian)維和闊(kuo)葉木纖(xian)維的含(han)量推薦值為大于80%，木(mu)材纖維的強度高(gao)，耐熱(re)性(xing)好，應用性(xing)能最(zui)佳。

松方(fang)密度

松方密(mi)度是纖(xian)(xian)維(wei)在蓬松狀態下單位(wei)體積的質量。松方密(mi)度是纖(xian)(xian)維(wei)形態的重要參(can)數。對于(yu)絮狀纖(xian)(xian)維(wei)素(su)纖(xian)(xian)維(wei)，可間接表征纖(xian)(xian)維(wei)的尺寸;對于粒(li)狀纖(xian)維(wei)(wei)素纖(xian)維(wei)(wei)，可(ke)表(biao)征纖(xian)維(wei)(wei)的制作工藝。松方密度(du)可(ke)采用松方密度(du)測定儀進行測定。絮(xu)狀纖(xian)維(wei)(wei)松方密度(du)應為(20-40)g/L;粒(li)狀纖(xian)維(wei)(wei)松方密度(du)應為(400-600)g/L。

結語

纖(xian)維素纖(xian)維廣泛(fan)用于瀝青路(lu)面、混凝(ning)土、砂漿(jiang)等領域(yu)，對(dui)防(fang)止(zhi)開裂、提(ti)高保(bao)水性(xing)、提(ti)高生產的穩定性(xing)和施工(gong)的合(he)宜性(xing)等有良好的效果(guo)。

絮狀纖(xian)(xian)維(wei)(wei)(wei)較粒狀纖(xian)(xian)維(wei)(wei)(wei)有較好(hao)的(de)高溫(wen)(wen)性(xing)能(neng)、低溫(wen)(wen)性(xing)能(neng)及(ji)對(dui)瀝青的(de)吸附(fu)能(neng)力。粒狀纖(xian)(xian)維(wei)(wei)(wei)素(su)纖(xian)(xian)維(wei)(wei)(wei)表面的(de)涂覆結構能(neng)保持(chi)較低的(de)含水(shui)量，很(hen)好(hao)地(di)克服了絮狀纖(xian)(xian)維(wei)(wei)(wei)素(su)纖(xian)(xian)維(wei)(wei)(wei)易(yi)吸水(shui)腐爛的(de)缺(que)點，制備工(gong)藝簡單(dan)可行。粒狀纖(xian)(xian)維(wei)(wei)(wei)密度(du)均(jun)勻，添加(jia)投料精(jing)準(zhun)，拌(ban)和分散更加(jia)均(jun)勻，具有較好(hao)的(de)推廣應用(yong)前景。實(shi)際(ji)工(gong)程應用(yong)可根據本文列舉的(de)性(xing)能(neng)參(can)數選(xuan)擇纖(xian)(xian)維(wei)(wei)(wei)素(su)纖(xian)(xian)維(wei)(wei)(wei)穩定(ding)劑并進行試驗，為(wei)相關(guan)工(gong)程提供參(can)考依據。