外文翻譯---廢棄混凝土再生新技術(shù)探索

1、<p>　　廢棄混凝土再生新技術(shù)探索</p><p>　　馬新偉1,　張東青2,　尹煒鋒2,　李　寧2</p><p>　　(1·哈爾濱工業(yè)大學(xué)(威海)土木工程系,　山東　威?！?64209;　2·哈爾濱工業(yè)大學(xué)材料科學(xué)與工程學(xué)院,　哈爾濱　150001)</p><p>　　【摘　要】　本文對目前廢棄混凝土再生技術(shù)的研究做了論述,并指

2、出了其中存在的一些問題。結(jié)合混凝土各組成部分的結(jié)構(gòu)特點,提出了通過低溫煅燒對廢棄混凝土綜合利用的新方法。在750℃溫度條件下煅燒1h,可以實現(xiàn)水泥漿與骨料的分離。脫水后的水泥漿可以重新獲得水化活性。得到的混凝土骨料可以滿足使用要求。</p><p>　　【關(guān)鍵詞】　廢棄混凝土;再生技術(shù);煅燒;水化活性;壓碎指標(biāo)</p><p>　　【中圖分類號】　TU352·8　　　　　【文獻(xiàn)標(biāo)

3、識碼】　A【文章編號】　1001-6864(2009)09-0004-02</p><p>　　國家“十五計劃”綱要指出:“堅持資源開發(fā)與節(jié)約并舉,把節(jié)約放在首位,法保護(hù)和合理使用資源,提高資源利用率,實現(xiàn)永續(xù)利用。推進(jìn)資源綜合利用技術(shù)研究開發(fā),加強廢舊物資回收利用,加快廢棄物處理的產(chǎn)業(yè)化,促進(jìn)廢棄物轉(zhuǎn)化為可用資源?！北Ｗo(hù)環(huán)境、節(jié)約能源、減少廢料、以持續(xù)的方式使用可再生資源是可持續(xù)發(fā)展戰(zhàn)略的重要內(nèi)容。建材工業(yè)是典

4、型的基礎(chǔ)原料工業(yè),在國民經(jīng)濟(jì)發(fā)展中具有重要作用。建材工業(yè)又是典型的資源、能源消耗型工業(yè),在其快速發(fā)展的同時,面臨著資源、能源的過度消耗和環(huán)境的嚴(yán)重污染。建筑和建材行業(yè)的根本出路就是走可持續(xù)發(fā)展的道路[1]。起初,我國對混凝土的利用僅是簡單的破碎充當(dāng)再生粗骨料,這種生產(chǎn)的再生骨料性能與天然粗骨料的性能存在一定差異,主要表現(xiàn)在密度低、吸水率高、壓碎指標(biāo)大,表明再生骨料的空隙率高,強度低,這主要是由于其表面附著有大量水泥砂漿及在破碎過程中引入

5、一定量的微裂紋的緣故[2],生成的混凝土性能低,耐久性、抗凍融、抗腐蝕能力差。研究者根據(jù)再生骨料再利用過程中存在的問題,對再生骨料進(jìn)行了物理、化學(xué)改性以及整形改性。如朱崇績等通過整形除去再生骨料表面的砂漿,使顆粒變得光滑,需水量降低,使所配</p><p>　　1．廢棄混凝土裂解溫度確定</p><p>　　混凝土是由水泥、粗細(xì)集料、礦物摻合料等加水拌合,經(jīng)水化硬化而形成的一種微觀不均勻,

6、宏觀均勻的人造石。廢棄混凝土在低溫煅燒時的溫度由水泥脫水溫度與石灰石分解溫度共同決定。</p><p>　　1·1　水泥水化產(chǎn)物脫水溫度</p><p>　　文獻(xiàn)認(rèn)為,含水礦物中普通吸附水的脫水溫度一般為100~110℃,存在于層狀硅酸鹽結(jié)構(gòu)中的層間水或膠體礦物中的膠體水多數(shù)要在200~300℃以內(nèi)脫水,個別要在400℃以內(nèi)脫水;架狀結(jié)構(gòu)的硅酸鹽結(jié)構(gòu)水則要在400℃左右才大量脫出

7、。結(jié)晶水在不同結(jié)構(gòu)中的礦物中結(jié)合程度不同,其脫水溫度也不同。結(jié)構(gòu)水是礦物中結(jié)合最牢的水,脫水溫度較高,一般要在450℃以上才脫水[5]。為了確定廢棄混凝土的低溫煅燒溫度,保證在該溫度條件下骨料和水泥漿能夠充分分離,水泥石完全脫水,本課題對水泥漿進(jìn)行了熱重分析(TGA),熱失重曲線及(TG)及差熱曲線(DTG)如圖1所示。</p><p>　　從圖1可以看出,水泥漿在100℃前后分別有一個明顯的失重過程,理論上應(yīng)當(dāng)

8、是失去自由水和弱吸附水所形成的過程。在500℃以前又有一個明顯的失重過程,該失重過程溫度范圍較窄,但失重速度較快,從水泥石的組成看應(yīng)當(dāng)是Ca(OH)2失水形成的。另一個水泥石脫水過程發(fā)生在682~775℃之間,脫水的峰值速率發(fā)生在740℃。這一過程脫水過程劇烈,持續(xù)時間較長,這一失水過程使C-S-H凝膠分解,重新生成為具有潛在水化活性的膠凝材料。溫度繼續(xù)升高,直至1000℃再無明顯的吸熱峰出現(xiàn)。另外,溫度再渡升高可能影響混凝土骨料的結(jié)構(gòu)

9、。因此,混凝土分解溫度確定為750℃。經(jīng)過高溫處理的水泥漿因脫水而重新獲得水化活性,這一性能已在實驗中得到證實。</p><p>　　1·2　碎石分解溫度</p><p>　　粗骨料(碎石)的成分主要由CaCO3和在少量的MgCO3組成,其中MgCO3的分解溫度較低,600℃就開始劇烈反應(yīng),CaCO3劇烈分解溫度則更高達(dá)到900℃左右,但其開始分解溫度較低,在650℃就開始分解。

10、所以在550~900℃范圍內(nèi)煅燒混凝土?xí)r,隨著溫度的升高,骨料發(fā)生分解的量增大,使骨料的強度降低。過渡區(qū)是混凝土的薄弱環(huán)節(jié),一方面攪拌時在骨料表面被水膜覆蓋,妨礙了水泥粒子與骨料表面接觸,骨料周邊水灰比變大,另一方面,水化反應(yīng)溶出的遷移性大的Ca2+、Al3+、SO4-3離子為使?jié)舛绕胶庀蚬橇媳砻鏀U散。在骨料表面附近,六角板狀結(jié)晶的氫氧化鈣和針狀結(jié)晶的鈣釩石的析出比較顯著,形成大且連續(xù)的空隙構(gòu)造[8]。使過渡區(qū)的水分也幾乎以層間水及自由

11、水的形式存在,所以在較低的煅燒溫度就可實現(xiàn)骨料與水泥砂漿的分離,理論上在300℃以上即可實現(xiàn)分離。為了探究煅燒溫度對骨料強度的影響,本試驗分別對600、700、800℃煅燒溫度時所得到的粗骨料壓碎值進(jìn)行了研究,并與天然碎石和直接破碎的混凝土進(jìn)行了比較,實驗結(jié)果如圖所示。</p><p>　　從圖2可知在燃燒溫度600℃時,碎石的壓碎指標(biāo)略高于天然碎石,而隨燃燒溫度的提高,壓碎指標(biāo)明顯增大,標(biāo)志著骨料強度降低。但在

12、800℃所得到的骨料強度仍高于混凝土直接破碎得到的骨料強度,所以在混凝土煅燒溫度不超過800℃時是可行的。</p><p><b>　　2　結(jié)語</b></p><p>　　根據(jù)混凝土各組分的結(jié)構(gòu)特點,采取煅燒的方法把骨料和水泥漿分離是可行的。經(jīng)分解后的粗骨料可以在新拌混凝土中應(yīng)用,其強度高于混凝土直接破碎得到的再生骨料。經(jīng)分離得到的水泥漿重新獲得了再次水化的活性。為

13、廢棄混凝土的回收以及骨料和水泥漿的再生和利用開辟了一條新的途徑。</p><p><b>　　參考文獻(xiàn)</b></p><p>　　[1]　水中和,曹蓓蓓,萬惠文.廢棄混凝土再生利用技術(shù)及其發(fā)展前景[J]·資源節(jié)約與綜合利用,2006,(3):8-11·</p><p>　　[2]　王耀新.混合應(yīng)用天然與再生骨料混凝土的基本

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16、究方法[M].北京:科學(xué)出版社,2005,236-249·</p><p>　　[8]　徐新生,徐衛(wèi)生.混凝土過渡區(qū)對混凝土物質(zhì)滲透性影響[J]·山東建材,1999,(3):10-13·</p><p>　　EXPLORATION ON RECYCLING TECHNOLOGY OF WASTE CONCRETE</p><p>　　M

17、A Xin-wei1,　ZHANG Dong-qing2,　YINWei-feng2,　LI Ning2</p><p>　　(1·Department of Civil Engineering, Harbin Institute ofTechnology at Weihai, Shandong Weihai 264209, China;2·School ofMaterials Science

18、 and Engineering, Harbin Institute ofTechnology, Harbin 150001, China)</p><p>　　Abstract:The current research situation on the recycling technology ofwaste concrete and existing problems in applicationwas su

19、mmarized·Consideringthe structural characteristics of cement paste and aggregate, a new recycling technology through calcination is presented·The cement paste and aggregates could be separated</p><p&

20、gt;　　at 750℃for one hour·The dehydrated cement paste can have reactivity again, and the aggregates can meet the requirement of application·</p><p>　　Key words:waste concrete;recyclyingte;chnology;c

21、alcination;reactivity;crushing index</p><p>　　National "tenth five-year plan" outline pointed out: "insists resource development and save the save itself, in the first place, protect and ratio

22、nally use method of resources, and improve the resource utilization rate, to achieve sustainable use. Push technology research and development resources comprehensive utilization of waste materials, strengthen recycling,

23、 accelerate the industrialization, promote waste disposal of waste into usable resources." Protect the environment and save energy, re</p><p>　　At first, the use of concrete in the crushing only a simpl

24、e as recycled coarse aggregate, the production of natural regeneration aggregate performance and the performance of coarse aggregate, main show there is some difference in density low, bibulous rate is high, crush index

25、is big, show the gap regeneration aggregate rate high, low intensity, and it is mainly because the surface adhesion has large cement mortar and crushing process in certain micro cracks of introducing the sake [2] and gen

26、er</p><p>　　1. Determine the decomposition temperature of waste concrete</p><p>　　Concrete is made of cement, thick aggregate, such as mineral admixture, the water hydration sclerosis regarding

27、mix-proportion formed a microscopic uneven, macro uniform man-made stone. Abandoned the concrete in low temperature calcination temperature by cement dehydration temperature decomposition temperatures decided together wi

28、th limestone.</p><p>　　1 · 1 cement hydration products dehydration temperature</p><p>　　Literature in minerals that water cut the dehydration temperature ordinary adsorption water for 100 ~

29、 110 ℃ commonly, exists in layer silicate structure between layers of the colloid water or colloid mineral water in 200 ~ 300 much ℃ in within dehydration, individual ℃ 400 within dehydration; Frame shape structure of si

30、licate structure in 400 ℃ water is only around large emerge. The minerals in different structure gesso combination of different degree, the dehydration temperature is different. S</p><p>　　Temperature（℃）<

31、/p><p>　　Slurry thermogravimetric analysis curves</p><p>　　From figure 1 in 100 ℃, water slurry before an obvious weightlessness, respectively, in theory should be losing process of free water and

32、weak adsorption water by the formation of the process. In 500 ℃ ago and have an obvious of weightlessness process, this weightlessness process temperature range is narrower, but weightlessness faster, the composition of

33、the cement paste.the watch from shall be the Ca (OH) 2 water loss formation. Another cement stone anhydration process occurs in 682 ~ 775 ℃ be</p><p>　　1 · 2 gravel decomposition temperature</p>

34、<p>　　The coarse aggregate (gravel) mainly by the ingredients in a small amount of CaCO3 and MgCO3 composition, which MgCO3 decomposition temperature is lower, 600 ℃ began to react vigorously CaCO3 decomposition tem

35、peratures, severe ℃ is high reached 900 around, but its start decomposing temperature is lower, at 650 ℃ began to decompose. So in 550 ~ 900 ℃ scope when calcined concrete, with the rise of temperature, aggregate ratio i

36、ncreases occurred decomposition, aggregate strength decreased. Transiti</p><p>　　600 700 800 Natural aggregate broken concrete</p><p>　　From graph 2 600 ℃ in combustion temperature that when

37、 the crush index, gravel, and slightly higher than the natural macadam with combustion temperature rise, crush index increased, marked the aggregate strength decreased. But in 800 ℃ obtained aggregate strength is still h

38、igher than the aggregate concrete crushing get directly in the concrete intensity, so no more than 800 ℃ calcination temperature is feasible.</p><p>　　2 .Epilogue</p><p>　　According to the struc

39、ture characteristics of various components of the concrete methods of, take the aggregate and pellets slurry separation is feasible. After the decomposition of coarse aggregate in concrete in new mix, its strength of con

40、crete application of crushing get directly than renewable aggregate. The slurry isolated from getting the hydration activity again. For the collection and aggregate concrete waste water and mud regeneration and use open

41、a new way.</p><p>　　References</p><p>　　[1] water and CaoBeiBei, WanHuiWen. Abandoned, recycled technology and its development of concrete [J] prospect, conservation of resources and comprehensi

42、ve utilization, 2006, (3) : 8-11 ·</p><p>　　[2] WangYaoXin. Mix with application of natural regeneration aggregate concrete, basic properties of concrete [J], 2005, (8) : 49-53 ·</p><p&g

43、t;　　[3] ZhuChong performance LiQiuYi, LiYunXia. Particles, of recycled aggregate concrete durability plastic [J], the influence of cement and concrete, 2007, (3) : 6-10 ·</p><p>　　[4] SunRongGuang, YuRu

44、i, XuanDongXing, the water and the mud. Old water high temperature treatment rehydration gelling properties research [J]. Journal of wuhan university of technology, 2007, (9) : 115-118 ·</p><p>　　[5] Yu

45、Rui, the water and the mud. XuanDongXing renewable water, modified study [J] DE 2009, (4) : 104-107 ·</p><p>　　[6] SidneyMindess · concrete (original second edition) [M]. WuKeRu, etc, Beijing: chem

46、ical industry translation press, 2005 · 1 ·</p><p>　　[7] WangPeiMing, research methods XuQian comfort. Materials [M]. Beijing: science press, 2005,236-249 ·</p><p>　　[8] XuXinShen