外文翻譯--高溫對(duì)水泥膏體回填強(qiáng)度和微觀性能的影響（節(jié)選）

1、<p>　　3535單詞,18300英文字符，4760漢字</p><p>　　出處：Fall M, Samb S S. Effect of high temperature on strength and microstructural properties of cemented paste backfill[J]. Fire Safety Journal, 2009, 44(4): 642-651

2、.</p><p>　　Effect of high temperature on strength and microstructural properties of cemented paste backfill</p><p>　　Fall M, Samb S S</p><p><b>　　Abstract</b></p>

3、<p>　　The main purpose of this research is to investigate the in?uence of high temperatures on the strength and microstructure (e.g. pore structure, porosity) of cemented paste backfill (CPB) through a series of ex

4、perimental tests. A laboratory experimental setup allowing the simulation of various high-temperature conditions is developed. Different types of CPB specimens are exposed to different high temperatures (100, 200, 400 an

5、d 600 ℃). The strength, porosity, pore size distribution and water absor</p><p>　　Keywords:Cemented paste back?ll;Fire;Temperature;Strength;</p><p>　　Microstructure;Tailings</p><p>

6、　　1 Introduction </p><p>　　During the last decade, cemented paste backfills (CPBs) have become increasingly popular in underground mining operations around the world [1-5]. CPB technology is considered super

7、ior to traditional hydraulic backfill methods in terms of both economic and environmental benefits [1-7]. Its application is very useful in ground support and maximizing the safe and economic recovery of ore. Indeed, in

8、mining operations, when ore bodies are extracted, large voids are created and massive pillars are le</p><p>　　CPBs typically consist of a mixture of dewatered tailings (generally composed of fine silt-size p

9、articles) from the milling or processing perations of the mine, water and hydraulic binders. The binder content is usually 3-7% by weight. The proportion of the solid (tailings+binder) is between 70% and 85% by weight. T

10、hese components are combined and mixed on the surface and transported (by gravity and/or pumping) to the underground mine workings, where the CPB can be used for the roles previously </p><p>　　An important p

11、arameter in judging the quality of the hardened paste backfill is its uniaxial compressive strength (UCS). Indeed, the UCS of the hardened backfill is often used in the practice to evaluate its stability or structural in

12、tegrity [10] since the test is relatively inexpensive and can be incorporated into routine quality control programs at the mine [11]. The function of the CPB has a considerable effect on the required mechanical (strength

13、) response. For example, when the CPB is used </p><p>　　As a result of the increased and intensive use of CPBs in underground mining operations, several studies [1-12,15-23] have been conducted to better und

14、erstand the properties (e.g. strength, microstructure) and determine different factors that can affect the properties. These studies reveal that different factors can affect the properties (strength, microstructure) of a

15、 given CPB [8,10,11,15], such as the characteristics of different CPB compo- nents (tailings, cement, water), geomechanical condi</p><p>　　Hence, considering the facts mentioned above, the main objectives of

16、 this research are to experimentally study: </p><p>　　the effect of high temperatures on the strength of CPBs, </p><p>　　the effect of high temperatures on the microstructure of CPBs </p>

17、<p><b>　　and </b></p><p>　　the development of the performance of CPBs when exposed to </p><p>　　high temperatures. </p><p>　　Following this introduction, the mater

18、ials used, a description of the developed experimental setup and the experimental tests performed are presented. Then the results are presented and discussed. Finally, the main conclusions are provided. </p><p

19、>　　2. Materials and methods </p><p>　　2.1. Materials </p><p>　　2.1.1. Tailings </p><p>　　Considering the fact that sulphidic tailings heated at a high temperature (250 ℃) can rel

20、ease toxic SO 2 [29], for safety reasons, ground silica (Si) was used to simulate tailings for the CPB mixtures. The Si contained 99.8% SiO 2 and showed a grain size distribution close to the average of 9 mine tailings (

21、originating from eastern Canada). The particle size distribution of the ground Si used is shown in Fig. 1. Tables 1 and 2 give the main physical and chemical characteristics of the Si. It can</p><p>　　2.1.2.

22、 Mixing water </p><p>　　Tap water was used to prepare all the sample mixtures. The amount of water was varied to obtain CPB mixtures with the desired consistencies. </p><p>　　2.1.3. Binder reage

23、nts </p><p>　　Portland cement type I (PC I) was used as the reference binding agent.</p><p>　　2.2. Mixing procedures and mix proportions </p><p>　　In order to produce CPB mixtures,

24、the tailings materials, binders and water were mixed and homogenized in a mixer with a double spiral. Table 3 presents the ingredients of the types of CPB prepared. The slump of all mixes was about 16 cm. The CPB mixture

25、s produced were then poured into curing moulds of 5 cm in diameter and 10 cm in height. The prepared moulds were then sealed and cured in an environmental chamber at a constant temperature (25 ℃) for periods of 7, 28 and

26、 50 days. The humidity of </p><p>　　2.3. Developed experimental setup and heating procedures </p><p>　　A schematic representation of the experimental setup deve- loped to simulate different high

27、-temperature conditions is illustrated in Fig. 2. The experimental setup consists mainly of an electronically controlled electric furnace with thermal insula- tion (1). This insulation reduces thermal loss. The heat in t

28、he furnace is produced by a heating system (see Fig. 2 for details). The heat is transferred to the surface of CPB samples by radiation, while heat is conducted into the CPB samples. The te</p><p>　　The heat

29、ing temperatures studied were 100, 200, 400 and 600 ℃. These cover the temperature range from ambient to a high-temperature value, greater than the maximal values of emperature reported [29] that CPB structures can be ex

30、posed through self-heating mechanism. The temperature in the furnace was elevated gradually at a rate of 5-7 ℃/min. The heating period was 2 h at the peak temperature. After heating was completed, the specimens were allo

31、wed to cool down to room temperature in the furnace.</p><p>　　2.4. Testing procedures </p><p>　　2.4.1. Uniaxial compression tests </p><p>　　Uniaxial compression tests were performed

32、 on the CPB speci- mens after different curing times for the different studied high temperatures. The specimens were tested in accordance with standard ASTM C 39 using a omputer-controlled mechanical press (MTS 10/GL). T

33、he press has a normal loading capacity of 50 kN. The compression tests were carried out at a constant deformation rate of 1 mm/min. The axial deformations were automatically recorded by an electronic data acquisition sys

34、tem. </p><p>　　2.4.2. Microstructure analysis </p><p>　　Four different techniques were used to experimentally in- vestigate the microstructure of CPBs. These techniques, described below, are mer

35、cury intrusion porosimetry (MIP), scanning electron microscopy (SEM), capillary absorption test (CP) and thermal analysis (TAn). </p><p>　　MIP: MIP measurements were performed using a Micromere- tics AutoPor

36、e III 9420 mercury porosimeter. Before MIP testing, all samples were first dried at 50 ℃ to constant mass. The MIP tests allowed for an evaluation of pore size distribution in the dried CPB samples. </p><p>

37、　　SEM: SEM observations were done on samples with a Hitachis 3500-N microscope. The samples were first dried at 50 ℃ to constant mass in a vacuum oven to remove the free water. Drying at this temperature did not appear t

38、o cause cracking. After that, the samples were vacuum impregnated with low viscosity epoxy, polished and then observed in backscatter electron mode. </p><p>　　CP: Since the results or parameters (sorptivity,

39、 capillary water absorption) obtained by performing the CP provided an indication of the pore structure inside a porous media, and thus, the ease with which ?uids can enter into and move through this porous material, CPs

40、 according to the method detailed by Hall [31] were performed to evaluate the pore structure of the CPB. Before undertaking CP, the CPB specimens were dried in an oven at 50 ℃ until a constant weight was reached. The pre

41、pared CPB sp</p><p>　　TAn: DTA/DTG thermo-analytical investigations were per- formed on hardened cement pastes of CPB, CPB samples and raw tailings samples. The tests were undertaken using the SDT apparatus

42、from TA Instruments allowing automatic registration of weight loss along thermal treatment of the sample. The tests were done with approximately 30 mg samples in an inert nitrogen atmosphere. The heating rate was 10 ℃/mi

43、n for all of the samples tested. </p><p>　　3. Results and discussions </p><p>　　3.1. Effect of high temperature on strength of CPBs </p><p>　　Figs. 3-6 summarize the main results of

44、 the study of the effect of high temperatures on the strength of CPBs. From these figures, it is obvious that high temperatures significantly affect the strength of CPBs. Fig. 3a shows the effect of heating on the compre

45、ssive strength of CPBs cured at different times (7, 28, 50 days), while Fig. 3b shows the residual compressive strength of the CPB specimens as a function of the heating temperature. The residual compressive strength aft

46、er heating at differe</p><p>　　Fig. 3 also shows that above 200 ℃, the strength of the CPB specimens begins to decrease. The lowest residual strengths are obtained at 600 ℃ (Fig. 3b). This deterioration of t

47、he strength ofCPBs exposed to temperatures higher than 200 ℃ may be attributed to the combined effects of three factors: (i) the thermal decomposition of hydrates and occurrence of dehydration- induced cracks as shown in

48、 Sections 3.2 and 3.3 and (ii) the development of microcracks at the interfaces between tailings and cem</p><p>　　However, the effect of high temperatures on the strength of CPB is dependant on the w/c cemen

49、t ratio (Fig. 4), tailings fineness (Fig. 5) and type (Fig. 6) of the CPB. Fig. 4 shows a typical example of the effect of heating temperatures on the strength of CPB specimens with different w/c ratios. It can be observ

50、ed that the strength of the CPBs with w/c ¼ 7 increases with the heating temperature up to 200 ℃, and afterwards, decreases with the temperature to reach at 600 ℃, a strength approximatel</p><p>　　Fig.

51、5 shows the effect of tailings fineness and heatingtemperature on the strength of CPBs with same w/c ratios (w/c ¼ 7). This figure indicates that CPBs made from coarse tailings are more negatively affected by high t

52、emperatures than CPBs composed of finer tailings. Indeed, it can be noted that from 20 to 200 ℃, the increase of CPB strength with heating temperature is low or non-existent for CPBs made from tailings with 25% or 0% fin

53、e particles, respectively. At 400 ℃, the CPBs composed of co</p><p>　　譯文 高溫對(duì)水泥膏體回填強(qiáng)度和微觀性能的影響</p><p><b>　　摘要</b></p><p>　　本研究的主要目的是探討高溫對(duì)水泥膏體回填強(qiáng)度和微觀組織(如孔隙結(jié)構(gòu)、孔隙度)的影響。一個(gè)實(shí)驗(yàn)室的

54、模擬實(shí)驗(yàn)裝置允許各種高溫條件下的設(shè)計(jì)與開(kāi)發(fā)。不同類型的水泥膏體回填標(biāo)本暴露于不同的高溫(100、200、400和600℃)條件下。分析強(qiáng)度、孔隙率、孔徑分布及水分對(duì)這些水泥膏體回填標(biāo)本的影響,然后進(jìn)行實(shí)驗(yàn)室研究。熱重和差熱分析研究也是高溫條件下的水泥膏體回填熱行為。結(jié)果表明,高溫對(duì)水泥膏體回填的性質(zhì)有很大影響。總的來(lái)說(shuō),在大多數(shù)研究中，逐漸升高的氣溫達(dá)到200℃時(shí)，水泥膏體回填具有更高的強(qiáng)度，并且水泥膏體回填的孔隙率和孔徑分布僅是稍微發(fā)

55、生變化。超過(guò)200℃時(shí),升高的溫度降低了水泥膏體回填s的強(qiáng)度。最明顯的強(qiáng)度降低發(fā)生在暴露的溫度超過(guò)400℃時(shí)。水泥膏體回填強(qiáng)度的降低伴隨有微觀結(jié)構(gòu)的顯著變化(孔隙率、孔徑大小及其分布、礦物相等)。此外,高溫對(duì)強(qiáng)度和水泥膏體回填s微觀組織的影響取決于水灰比和尾礦的類型。</p><p>　　關(guān)鍵字：水泥膏體回填；火；溫度；強(qiáng)度；微觀結(jié)構(gòu)；尾礦</p><p><b>　　1 介紹&

56、lt;/b></p><p>　　采礦作業(yè)時(shí),當(dāng)?shù)V體被采出后,留下了大量的空洞，在原來(lái)的地方僅留有一部分礦柱來(lái)保證穩(wěn)定性。那剩下的礦柱是一種資源的流失,但開(kāi)采礦柱常常會(huì)造成巨大的地表沉陷。地下孔洞回填的穩(wěn)定性,提高了周圍地區(qū)挖掘的安全性和有效性。一個(gè)良好的水泥膏體回填將最大限度地減少礦床損失,并提高上覆巖層的穩(wěn)定性。此外，水泥膏體回填技術(shù)是一種有效的管理尾礦的方法，因?yàn)榈叵滤喔囿w回填的存儲(chǔ)可以減少尾礦的體

57、積，這個(gè)體積達(dá)到60%。它也最大限度地減輕了在地面建立尾礦管理系統(tǒng)的需要，因此,明顯降低了相關(guān)的成本與表面尾礦的管理費(fèi)用。</p><p>　　水泥膏體回填一般是一種脫水的尾礦混合物，這種混合物是由礦石、水、液體粘合劑經(jīng)過(guò)銑削碾磨而成的。粘合劑的含量通常占到3～7%。固體所占比例大約在70%～85%。這些成分在地面混合然后運(yùn)至地下礦床開(kāi)采工作面，水泥膏體回填在工作面擔(dān)負(fù)前面提到的任務(wù)。</p>&l

58、t;p>　　判斷回填硬化質(zhì)量的一個(gè)重要參數(shù)是它的巖石單軸抗壓強(qiáng)度。的確，硬化回填的巖石單軸抗壓強(qiáng)度常在實(shí)踐中用來(lái)評(píng)價(jià)其穩(wěn)定性和結(jié)構(gòu)的完整性，這是由于這種測(cè)試是相對(duì)便宜的并且在礦床開(kāi)采中可以被納入日常質(zhì)量控制程序。水泥膏體回填功能對(duì)機(jī)械（強(qiáng)度）反應(yīng)有很大的影響。例如，當(dāng)水泥膏體回填用在充填空洞或地面處理時(shí)，在前期為了消除液化的危險(xiǎn)，在一些礦上將回填強(qiáng)度的目標(biāo)值規(guī)定在100KPa～300KPa。然而，在切割和回填采礦中，28天內(nèi)必須保

59、持回填穩(wěn)定性，抗壓強(qiáng)度通常是低于1MPa的。當(dāng)回填是用于支撐頂板時(shí)，一般要求強(qiáng)度值高于4MPa。然而,抗壓強(qiáng)度并不是唯一表征水泥膏體回填結(jié)構(gòu)完整性的參數(shù)。水泥膏體回填的微觀結(jié)構(gòu)很大程度上影響著它的強(qiáng)度和流動(dòng)運(yùn)輸能力。事實(shí)上,人們普遍接受了這一點(diǎn)：流動(dòng)運(yùn)輸特性強(qiáng)烈的影響著膠結(jié)材料的使用壽命和完整性。例如,入口處的潛在的有害材料,如硫酸鹽和氧擴(kuò)散和或毛細(xì)管運(yùn)輸退化，會(huì)導(dǎo)致水泥膏體回填膠結(jié)基質(zhì)的降解，同時(shí)，硅酸鹽的侵蝕會(huì)導(dǎo)致強(qiáng)度降低。<

60、/p><p>　　由于在地下采礦作業(yè)中水泥膏體回填的利用不斷增加和集中，已經(jīng)有幾項(xiàng)研究 開(kāi)始分析其性能并確定影響其性能的因素。研究表明，不同的因素會(huì)影響特定水泥膏體回填的特性,如不同水泥膏體回填成分的特性，礦石的地質(zhì)力學(xué)條件、固化條件等。然而，所有的這些針對(duì)水泥膏體回填的性能進(jìn)行的研究卻忽視了火或高溫對(duì)其性能的影響。此外，大部分由這項(xiàng)高溫對(duì)水泥材料性能的影響而得出的結(jié)論應(yīng)用到了普通膠結(jié)材料中。同時(shí)，因?yàn)樗喔囿w回填不

61、同于普通混凝土，這些結(jié)果可能不太正確。這意味人們對(duì)水泥膏體回填的火或高溫阻力不太了解?？紤]到水泥膏體回填有時(shí)暴露于高溫條件下，這種認(rèn)識(shí)上的缺乏需要及時(shí)解決。地下礦山開(kāi)采作業(yè)中的高溫來(lái)源主要是礦井火災(zāi)和與水泥膏體回填結(jié)構(gòu)相近的巖體由于硫化礦物的氧化集中產(chǎn)生的熱效應(yīng)。此外，水泥膏體回填結(jié)構(gòu)的集中崩潰，允許大量的空氣混合到反應(yīng)物質(zhì)，就產(chǎn)生了像在加拿大各種各樣的地下采礦作業(yè)中看到的水泥膏體回填熱效應(yīng)。</p><p>　

62、　因此,考慮到上面提到的事實(shí),本課題的主要目的是研究:</p><p>　　高溫對(duì)水泥膏體回填的強(qiáng)度的影響</p><p>　　高溫對(duì)水泥膏體回填微觀結(jié)構(gòu)的影響</p><p>　　和當(dāng)接觸到過(guò)高溫時(shí)水泥膏體回填的性能變化。</p><p>　　以下這個(gè)說(shuō)明，對(duì)其所使用的材料、功能、實(shí)驗(yàn)裝置和實(shí)驗(yàn)方法進(jìn)行了介紹。隨后對(duì)結(jié)果進(jìn)行了全面的闡述和討

63、論。最后，提供了主要結(jié)論。</p><p><b>　　2 材料和方法</b></p><p><b>　　2.1.材料</b></p><p><b>　　2.1.1尾礦</b></p><p>　　考慮到含硫化物的尾礦在高溫加熱到250℃時(shí)會(huì)釋放出有毒氣體SO2，為了安全起

64、見(jiàn),用研磨好的Si作為水泥膏體回填的混合物來(lái)模擬尾礦。這種Si包含99.8%的SiO2，其粒度分布接近9個(gè)礦山尾礦(源自加拿大東部)晶粒的平均分布值。Si的晶粒尺寸見(jiàn)圖1。表格1和2給出了硅的主要物理和化學(xué)性質(zhì)。從圖中可以看出，Si大約含有45%的精細(xì)顆粒，將Si定為介質(zhì)尾礦。它的分選性很好，均勻性系數(shù)為16.2并且不含硫化物(表2)。上述硅尾礦(介質(zhì)尾礦)摻雜了粗糙的地面硅顆粒，最后的混合尾礦材料比較粗糙(精細(xì)度<30%，表3)

65、。導(dǎo)致含有0～25%的精細(xì)顆粒。另外，為了分析尾礦的熱行為，從不同于一般的礦物學(xué)的觀點(diǎn)出發(fā)，在加拿大東部的金礦采集了另外兩種尾礦(TA，TB)。這兩種尾礦的粒度分布、主要物理化學(xué)性質(zhì)如圖1，在表格1和2中的TA取自一個(gè)高度改變的片巖。這個(gè)片巖主要由石英、綠泥石、莫斯科石(或絹云母)、伊利石、石膏、硫鐵礦組成。TB來(lái)自變質(zhì)的巖漿巖，具有硫化礦物的特點(diǎn)。從表2可以看到TA的硫化物含量(5.4%)相對(duì)較低，TB卻富含大量的硫化物(30.1%)

66、。</p><p><b>　　2.1.2拌制水</b></p><p>　　用自來(lái)水拌制所有樣品的混合物。水的質(zhì)量不同是為了獲得水泥膏體回填混合物的一致性。</p><p>　　2.1.3粘結(jié)劑的試劑</p><p>　　用I型普通硅酸鹽水泥(PC)作為粘結(jié)劑。</p><p>　　2.2混合方

67、法和混合比例</p><p>　　為了產(chǎn)生水泥膏體回填混合物，將尾礦材料、粘結(jié)劑和與水混合，在一個(gè)有雙重螺旋的器皿中攪拌均勻。配料表3給出了精制水泥膏體回填的成分。將拌制好的水泥膏體回填混合物倒入一個(gè)直徑為5cm、高度為10cm的模具內(nèi)。隨后就把模具密封并放在在一個(gè)恒溫室(25℃)里，分別存放7天、28天、50天。濕度保持不變 (大約70%)。不同的實(shí)驗(yàn)標(biāo)本，在不同時(shí)期、不同的溫度下用不同的實(shí)驗(yàn)裝置進(jìn)行加工處理。

68、</p><p>　　2.3 先進(jìn)的實(shí)驗(yàn)裝置和加熱程序</p><p>　　在圖2中概要的說(shuō)明了模擬不同的高溫條件的實(shí)驗(yàn)裝置。主要的實(shí)驗(yàn)裝置是具有保溫功能的電爐。這層屏障可以減少熱損失。熱是由供暖系統(tǒng)產(chǎn)生的。熱量通過(guò)輻射傳到水泥膏體回填樣品的表面，熱量就進(jìn)入了水泥膏體回填樣品。爐子里的溫度是由一個(gè)自動(dòng)控制器調(diào)節(jié)的，調(diào)節(jié)溫度精確到0.5℃。它連接一個(gè)非常敏感的溫度傳感器，能夠感應(yīng)爐子的溫度，

69、然后把數(shù)據(jù)傳輸?shù)娇刂破鳌?lt;/p><p>　　分別在100、200、400和600℃條件下進(jìn)行實(shí)驗(yàn)。溫度變化從周圍環(huán)境溫度到高溫，遠(yuǎn)高于水泥膏體回填結(jié)構(gòu)通過(guò)自行發(fā)熱機(jī)理產(chǎn)生的溫度。爐溫以每分鐘5～7℃逐漸升高。加熱2小時(shí)后達(dá)到峰值溫度。加熱結(jié)束后，讓樣品在爐子里冷卻到室溫。冷卻后,按照下面的方法進(jìn)行力學(xué)性能試驗(yàn)和分析標(biāo)本的微觀結(jié)構(gòu)。</p><p><b>　　2.4 實(shí)驗(yàn)步驟&

70、lt;/b></p><p>　　2.4.1 單軸壓縮試驗(yàn)</p><p>　　在不同的高溫條件下，固化后對(duì)水泥膏體回填樣品進(jìn)行單軸壓縮試驗(yàn)。按照ASTM標(biāo)準(zhǔn)使用電腦控制的機(jī)械壓力機(jī)對(duì)樣品加壓。正常承載能力為50kN。進(jìn)行壓縮試驗(yàn)的變形速率始終控制在1mm/min。電子數(shù)據(jù)采集系統(tǒng)自動(dòng)記錄樣品的軸向變形。</p><p>　　2.4.2 微觀結(jié)構(gòu)分析</

71、p><p>　　用四種不同的技術(shù)分別來(lái)研究水泥膏體回填s的顯微結(jié)構(gòu)。這些技術(shù)是，汞浸入測(cè)試法(MIP)、電子顯微鏡掃描(SEM)、毛細(xì)管吸收實(shí)驗(yàn)(CP)、熱分析(TAn)。</p><p>　　MIP：進(jìn)行測(cè)試之前，將所有樣品在50℃條件下使其干燥。汞浸入測(cè)試法可以實(shí)現(xiàn)對(duì)干燥的水泥膏體回填樣品空隙尺寸分布分析。</p><p>　　SEM：用3500-N型顯微鏡掃描樣品

72、。將樣品放在溫度為50℃條件下加熱以有效的去除游離水。在此溫度下干燥似乎并沒(méi)有引起開(kāi)裂。之后，樣本變?yōu)檎婵詹⒑械驼扯鹊沫h(huán)氧樹(shù)脂，磨光后在背散射電子模式下觀察。</p><p>　　CP：既然從毛細(xì)管實(shí)驗(yàn)可以根據(jù)跡象和空隙結(jié)構(gòu)獲得結(jié)果和相應(yīng)參數(shù)，因此液體可以很自然的進(jìn)入和流過(guò)多孔材料，毛細(xì)管實(shí)驗(yàn)可以分析水泥膏體回填的多孔結(jié)構(gòu)。在進(jìn)行毛細(xì)管實(shí)驗(yàn)前，將水泥膏體回填樣品放在50℃的爐中加熱直到樣品達(dá)到恒定重量。然后將制

73、備好的標(biāo)本放置在水里。將試樣密封，以避免蒸發(fā)。在特定的時(shí)間間隔里，稱出試樣的質(zhì)量。吸收的水的質(zhì)量可以通過(guò)試樣浸入水的體積計(jì)算出來(lái)。</p><p>　　熱分析：在水泥膏體回填硬化水泥漿體、水泥膏體回填樣品、原尾礦試樣中進(jìn)行熱分析樣品和原始尾礦的樣品實(shí)驗(yàn)。實(shí)驗(yàn)使用特殊儀器自動(dòng)檢測(cè)進(jìn)行熱處理試樣的重量變化。實(shí)驗(yàn)需要大約30mg試樣。</p><p><b>　　3 研究結(jié)論及討論&l

74、t;/b></p><p>　　3.1 高溫對(duì)水泥膏體回填s強(qiáng)度的影響</p><p>　　圖3～6概括了高溫對(duì)水泥膏體回填強(qiáng)度的影響。從這些數(shù)據(jù)可以明顯看出，高溫對(duì)水泥膏體回填強(qiáng)度有明顯影響。圖3a表明了加熱在不同時(shí)期(7，28歲，50天)對(duì)水泥膏體回填抗壓強(qiáng)度的影響，而圖3b表明水泥膏體回填樣品的殘余抗壓強(qiáng)度是加熱溫度的函數(shù)，在不同溫度加熱后的殘余抗壓強(qiáng)度可以用UCS/UCS20

75、比率表示。UCS是水泥膏體回填在溫度Ｔ時(shí)的強(qiáng)度，UCS20是水泥膏體回填在20℃時(shí)的初始強(qiáng)度。從圖3可以看出，忽略固化時(shí)間，增加加熱溫度到200℃時(shí)水泥膏體回填強(qiáng)度增加。水泥膏體回填樣品在200℃時(shí)的強(qiáng)度是在室溫下的1.5～2.0倍。溫度由20℃增加到200℃時(shí)增加的水泥膏體回填強(qiáng)度可歸因于自由水流失與部分水分的汽化。的確，眾所周知，在溫度范圍從20℃～200℃，濕度與水泥材料的強(qiáng)度有很大關(guān)系。它假定水軟化水泥膠結(jié)材料表面或衰減凝膠的凝

76、膠粒子之間的力量，因而減少了其強(qiáng)度。因此，在溫度達(dá)到200℃時(shí)觀測(cè)到的水泥膏體回填強(qiáng)度增加的原因可能是一般粘合膠體的固化或是由于吸收水分釋放導(dǎo)致的粒子表面力的增加。在混凝土暴露于高溫條件下程孫俐也得到了同樣的實(shí)驗(yàn)結(jié)果。既然水泥膏體回填中水分的流失比較平緩，類似于在其</p><p>　　圖3還表明，溫度超過(guò)200℃時(shí)，水泥膏體回填樣品的強(qiáng)度開(kāi)始下降。在600℃時(shí)殘余強(qiáng)度最低。溫度超過(guò)200℃強(qiáng)度的退化可歸結(jié)于以下

77、三個(gè)因素的綜合作用：(1)水化合物的熱分解和水化合物誘導(dǎo)裂縫發(fā)生脫水(2)發(fā)展過(guò)程中的界面裂紋由于尾礦集料與水泥硬化漿體熱的不兼容。除了上述因素，對(duì)于溫度高于400℃的情況，第三個(gè)參量或許可以解釋水泥膏體回填強(qiáng)度下降或600℃時(shí)強(qiáng)度最低的原因。這個(gè)參量是水泥膏體回填中大裂縫的發(fā)展。的確，像我們觀察到的，該水泥膏體回填樣品加熱到600℃時(shí)在其表面出現(xiàn)許多裂縫。這些裂縫，不像在低于400℃時(shí)觀察到的，可以得出結(jié)論，由于水泥膏體回填的低滲透性

78、，在溫度高于400℃時(shí)產(chǎn)生了極高的水蒸氣壓力，這種內(nèi)部壓力往往過(guò)高以至于水泥膏體回填無(wú)法抵抗，因?yàn)槠淦骄估瓘?qiáng)度僅有300kPa。除了開(kāi)裂的因素，當(dāng)溫度達(dá)到600℃或是更高時(shí)，粘合劑（水泥膏體回填強(qiáng)度的主要來(lái)源）在很大程度上影響脫水，并會(huì)失去其膠結(jié)能力。這種假設(shè)在第3.3節(jié)中得到了驗(yàn)證。</p><p>　　然而,高溫對(duì)水泥膏體回填強(qiáng)度的影響依賴于其水灰比(圖4)、尾礦細(xì)度(圖5)和類型(圖6)。圖4是一個(gè)在不同

79、的水灰比條件下典型的高溫影響水泥膏體回填強(qiáng)度的例子。可以看出在水灰比為7時(shí)隨著溫度增加到200℃水泥膏體回填的強(qiáng)度在增加，然后，隨著溫度降低到600℃其強(qiáng)度逐漸下降，600℃時(shí)強(qiáng)度近似等于20℃時(shí)的強(qiáng)度。然而，當(dāng)水灰比等于9時(shí)，隨著溫度增加到400℃強(qiáng)度增大。400℃到600℃，強(qiáng)度降低，600℃時(shí)的強(qiáng)度值低于其在400℃時(shí)的強(qiáng)度。600℃時(shí)有著較高水灰比卻較低剩余強(qiáng)度應(yīng)歸因于水灰比的增加和變硬的水泥膏體回填的滲透性。加熱時(shí)由于較高的蒸

80、汽壓力和溫度梯度，增加的含水率對(duì)水泥基體的物理完整性有負(fù)面影響，增加的滲透性會(huì)產(chǎn)生積極的影響。換句話說(shuō),，高溫時(shí)水灰比和相應(yīng)的滲透性之間的競(jìng)爭(zhēng)扮演的角色不是微不足道的。從理論上講，可能對(duì)每種水泥膏體回填都有確定的水灰比。另外一個(gè)來(lái)解釋600℃時(shí)強(qiáng)度較低的原因應(yīng)該是有較高水灰比的水泥膏體回填就有較低的強(qiáng)度，因此對(duì)裂縫的發(fā)展也就有較弱的抵抗性。從圖４中可以看出，在水灰比等于７、溫度為200℃時(shí)強(qiáng)度達(dá)到最大，而水灰比等于９時(shí)其最大強(qiáng)度值在40