外文翻譯--輔助性膠凝材料對混凝土水化熱的改善作用

1、<p><b>　　外文原文：</b></p><p>　　The effects of supplementary cementing materials</p><p>　　in modifying the heat of hydration of concrete</p><p>　　Yunus Ballim Peter C.

2、Graham</p><p>　　Received: 23 February 2008 / Accepted: 17 September 2008 / Published online: 23 September 2008</p><p><b>　　Abstract</b></p><p>　　This paper is intended t

3、o provide guidanceon the form and extent to which supplementary cementing materials, in combination with Portland cement, modifies the rate of heat evolution during the early stages of hydration in concrete. In this inve

4、stigation, concretes were prepared with fly ash,condensed silica fume and ground granulated blastfurnace slag, blended with Portland cement in proportions ranging from 5% to 80%. These concretes were subjected to heat of

5、 hydration tests under</p><p>　　adiabatic conditions and the results were used to assess and quantify the effects of the supplementary cementing materials in altering the heat rate profiles of concrete. The

6、paper also proposes a simplified mathematical form of the heat rate curve for blended cement binders in concrete to allow a design stage assessment of the likely early-age time–temperature profiles in large concrete stru

7、ctures. Such an assessment would be essential in the case of concrete structures where the potential for </p><p>　　Keywords: Heat of hydration _ Fly ash _ Silica fume _ Slag _ Concrete</p><p>　　

8、1 Introduction</p><p>　　Supplementary cementing materials, such as ground granulated blastfurnace slag (GGBS), fly ash (FA) and condensed silica fume (CSF), are now routinely used in structural concrete. Use

9、d judiciously, these materials are able to provide improvements in the economy, microstructure of cement paste as well as the engineering properties and durability of concrete. They also alter the rate of hydration and c

10、an influence the time–temperature profile in large concrete elements.</p><p>　　This paper is aimed at an improved understanding of the way in which the early-age heat of hydration characteristics of concrete

11、 are altered by the addition of supplementary cementing materials (SCM), in combination with Portland cement, as a part of the binder. Importantly, in the design and construction of large concrete elements, where the ext

12、ent of temperature rise is of concern, our ability to reliably predict the early-age temperature differentials in the concrete requires a careful unders</p><p>　　In the investigation reported here, concrete

13、samples containing combinations of Portland cement with GGBS, FA or CSF were tested in an adiabatic calorimeter in order to determine their heat of hydration characteristics. The test programme was limited to binary blen

14、ds of the materials, i.e., each test was limited to a combination of Portland cement and one supplementary material and all concretes were prepared at the same water:binder (w/b) ratio. For each type of supplementary mat

15、erial, concrete</p><p>　　were prepared with supplementary material replacing between 5% and 80% of the Portland cement, depending on the type of SCM.</p><p>　　Concrete samples with a volume of a

16、pproximately 1 l were tested in the adiabatic calorimeter. The adiabatic calorimeter that was used in the test programme is based on the principle of surrounding a concrete sample with an environment in which the tempera

17、ture is controlled to match the temperature of the hydrating concrete itself, thus ensuring that no heat is transferred to or from the sample and the rise in temperature measured is solely due to the heat Mevolved by the

18、 hydration process. This </p><p>　　Since the rate of evolution of heat during theMhydration of cementitious materials is influenced by Mthe temperature at which the reaction takes place, there is no unique a

19、diabatic heat rate curve for a particular cement or combination of cementitious materials. Comparisons of the heat rate performances of materials must, therefore, be made on the basis of the degree of hydration or maturi

20、ty. In this paper, the results are expressed in terms of maturity or t20 h, which refers to the equivalent t</p><p>　　2 Concrete materials and mixtures</p><p>　　Concrete materials which are comm

21、only used and readily available in South Africa were used in these tests. The Portland cement complied with SABS EN197-1, type CEM I class 42.5 [5] and the GGBS, fly ash and silica fume complied with SABS 1491 Parts 1, 2

22、 and 3 [6–8], respectively. The oxide contents of the binder materials were determined by XRF analysis and the results are shown in Table 1. The range of replacement levels by each of the three supplementary materials us

23、ed, together with the concr</p><p>　　The concrete mixture proportions were kept the same throughout, except that the composition and relative proportion of the binder was changed as required. All the concret

24、es therefore had a w/b ratio of approximately 0.67 and the water content was sufficient to compact the concrete by manually stamping the sample holder. All the mixture components, including the water, were stored in the

25、same room as the calorimeter at least 24 h before mixing. This allowed the temperature of the materials to equ</p><p>　　The silica sand used in the concretes was obtained in three size fractions and these we

26、re recombined as needed for the mixing operation to ensure a uniform sand grading for each concrete. The stone used in the concrete was a washed silica, largely single-sized and 9.5 mm in nominal dimension. </p>&

27、lt;p>　　3 Conclusions</p><p>　　The intention of the project reported in this paper was Nto quantify the effects of supplementary cementing materials on the rate of heat evolution in Portland cement concret

28、es. In particular, the focus was on providing information on the rate of heat evolution in a way that would allow improved prediction of the internal concrete temperature profiles during construction of large or high-str

29、ength concrete elements. In this regard and given the parameters of the concretes used, the study has show</p><p>　　evolution. </p><p>　　Up to a replacement level of 15%, the addition of CSF

30、in Portland cement binders does not significantly alter the heat-rate profile of concrete. The most significant effect noted was an approximately 9% increase in the peak rate of hydration when 15% of the Portland cement

31、was replaced by CSF. However, the addition of 10% and 15% CSF had a marked effect in reducing the time to reach the peak rate of hydration.</p><p>　　The presence of the SCM’s assessed in this investigation h

32、ave the effect of stimulating the hydration of the CEM I in the blended binder This stimulated hydration results from the consumption of calcium hydroxide, the dilution effect</p><p>　　and hydration nucleati

33、on site effect. This stimulation of hydration is strongest with the addition of CSF, moderate in the case of GGBS and weak in the case of FA.</p><p>　　In the absence of a more reliable heat-rate curve for co

34、ncrete containing supplementary cementitious materials, the model proposed in Eqs. 6–8 can be used to provide a first-estimate of the temperature profiles at the design stage of a temperature-sensitive concrete structure

35、.</p><p>　　References</p><p>　　1. Ballim Y, Graham PC (2003) A maturity approach to the rate of heat evolution in concrete. Mag Concr Res 55(3). doi:10.1680/macr.55.3.249.37571</p><p&

36、gt;　　2. Koenders EAB, van Breugel K (1994) Numerical and experimental adiabatic hydration curve determination. In: Springenschmid R (ed) Thermal cracking in concrete at early ages. E&FN Spon, London</p><p&

37、gt;　　3. Maekawa K, Chaube R, Kishi T (1999) Modelling of concrete performance. Spon Press, London</p><p>　　4. Gibbon GJ, Ballim Y, Grieve GRH (1997) A low cost, computer-controlled adiabatic calorimeter for

38、determining the heat of hydration of concrete. ASTM J Test Eval 25(2):261–266</p><p><b>　　中文翻譯：</b></p><p>　　輔助性膠凝材料對混凝土水化熱的改善作用</p><p>　　尤努斯巴林/王澤長格雷厄姆</p><p&

39、gt;　　收稿日期：2008年2月23日/接受日期：08年9月17日/發(fā)表日期：2008年9月23日</p><p>　　摘要：這篇文章在形式和程度上，對結(jié)合波特蘭水泥的輔助性凝膠材料，在混凝土水化作用早期階段熱演化速率的改善進行了指導(dǎo)。在這次調(diào)查中，混凝土由粉煤灰，硅灰和地面濃縮?；郀t礦渣，兌入5％至80％比例的波特蘭水泥來制備。這些混凝土在高溫條件下進行絕熱水化試驗，試驗結(jié)果被用來評估和量化輔助性膠凝材料對

40、混凝土水化放熱速率改變的作用。該文件還提出了混凝土混合水泥粘合劑熱率曲線的簡化數(shù)學(xué)公式，使大型建筑早期時間的溫度近似分布可以進行評估。這種評估在混凝土結(jié)構(gòu)具因熱而至開裂的情況是必不可少的。</p><p>　　關(guān)鍵詞：水化熱、粉煤灰、硅粉爐渣的混凝土</p><p><b>　　1、介紹</b></p><p>　　輔助膠凝材料，如GGBS（地

41、面?；郀t礦渣），F(xiàn)A（粉煤灰）和CSF（濃縮硅粉）的，這些都是現(xiàn)在常規(guī)使用的材料。用得好的，這些材料能夠在經(jīng)濟，微觀結(jié)構(gòu)以及水泥漿體的工程性質(zhì)及混凝土的耐久性上提供改善。他們還改變了水化的速度，可以影響到大型混凝土構(gòu)件上隨時間變化的溫度分布。</p><p>　　本文的目的是為更好地理解SCM（輔助性膠凝材料）作為粘結(jié)劑，并與波特蘭水泥的組合而成的添加劑如何來改變混凝土早期水化放熱特性的。重要的是，在設(shè)計和建造

42、的大型混凝土構(gòu)件，那里的溫度上升幅度令人關(guān)注，我們有能力可靠地預(yù)測混凝土的早期溫差，但需要對水化放熱的速度進行仔細(xì)了解。從本質(zhì)上說，本文的目的是為提供含輔助性凝膠材料的混凝土放熱效率函數(shù)。這是在設(shè)計和建設(shè)大型建筑或高強度結(jié)構(gòu)時必須的基本信息，由于熱應(yīng)變有可能導(dǎo)致有害的開裂和/或耐久性損失。</p><p>　　在這份調(diào)查報告里，由SCM（輔助性膠凝材料）GGBS（地面?；郀t礦渣），F(xiàn)A（粉煤灰）和CSF（濃縮硅

43、粉）混合組成的混凝土樣本在絕熱的量熱儀鐘進行試驗，來確定它們的水化放熱的特性。測試方案受限于材料，即二元共混體系，每個測試僅限于波特蘭水泥和一項補充材料組合，所有混凝土是在同一水配制：水與粘結(jié)劑的比值。對于每個類型的輔助材料，混凝土制備了輔助材料取代波特蘭水泥5％至80％，取決于輔助性凝膠材料的類型。在絕熱量熱儀用有大約1升體積的混凝土樣品進行檢測。在測試程序中使用的絕熱量熱儀是根據(jù)，使樣品混凝土周圍的溫度能夠控制的與混凝土水化時的溫度

44、一致，來確保沒有任何熱量轉(zhuǎn)移至樣品或是沒有任何熱量從混凝土轉(zhuǎn)移至周圍環(huán)境，測得提升的問題完全是來自于混凝土水化作用的放熱過程。吉本等人已經(jīng)詳細(xì)描述了這量熱儀。由于膠凝材料水化時放熱速率受溫度變化的影響，所以沒有唯一的絕熱熱率曲線和凝膠材料的組合。對材料放熱速度性能的比較必須建立在水化程度的基礎(chǔ)之上。在這個文件中，結(jié)果表示在條件成熟或時間20小時時，其中提到的水化等效時間在20℃。巴林和格雷厄姆以這樣方式描述了熱率函數(shù)和使用它的理由。 &

45、lt;/p><p>　　2、混凝土材料及混合物</p><p>　　在南非混凝土作為常用的和現(xiàn)成的材料使用于這些測試。粘合劑材料的氧化物含量的由XRF測定分析，結(jié)果如表1所示。在更替水平范圍內(nèi)的三個輔助性材料混凝土的配合比。</p><p>　　具體混凝土混合比例整個保持不變，除了粘結(jié)劑組成和相對比例需要更改。因此，所有的混凝土w/ b(水與粘合劑)比值約為0.67，水

46、含量都足通過手動沖壓樣品以壓縮混凝土。所有的混合物組成部分，包括水，被存放在同一個房間作為量熱儀，過至少24小時后混合。這使得該材料在溫度達到19±1℃的平衡室溫下。每個1.2升的混凝土樣品通過手工攪拌制作與一個鋼的容器中，然后在絕熱測試開始后15分鐘內(nèi)加水的混合物。所有的測試都是開始于溫度18℃到20攝氏度之間，并且量熱儀要持續(xù)測量大約4天的時間。二氧化硅在混凝土用砂，得到3個大小不同組分，這些都是作為重組混合操作的必需步驟

47、，以確保統(tǒng)一每個等級砂混凝土。混凝土中的石子是被洗過的硅，主要是大量單一大小的和9.5毫米的。</p><p><b>　　3、結(jié)論</b></p><p>　　本文中該項目的目的是為了報道輔助性凝膠材料對混凝土水化熱的改善作用。特別是，尤其是提供了發(fā)熱速率信息，將允許人們改進預(yù)測大型或高強度混凝土構(gòu)件結(jié)構(gòu)的內(nèi)部溫度分布。通過利用這些混凝土做的試驗，而提供的這方面的參

48、數(shù)，該項研究表明：</p><p>　　含地面?；郀t礦渣和粉煤灰的波蘭特水泥的熱反應(yīng)速率的峰值隨著兩者含量的增加而減小。</p><p>　　添加劑：地面?；郀t礦渣和粉煤灰。</p><p>　　除粉煤灰替代品含量高達80％以外，其熱反應(yīng)速率達到峰值的時間隨著混凝土中地面?；郀t礦渣和粉煤灰含量的增加而減少。如果粉煤灰含量達80％，熱反應(yīng)速率達到峰值的時間會明顯

49、的增加。達到15％的更替水平時，混凝土中濃縮硅粉含量的改變不會顯著改變混凝土熱反應(yīng)速率。最顯著的影響是混凝土水花速率峰值有9％的增長，當(dāng)濃縮硅粉替代了15％波蘭特水泥時。然而，10％和15％含量濃縮硅粉的對減少混凝土達到水化縫制的時間，起到了顯著的效果。</p><p>　　在這次研究中表明輔助性凝膠材料在結(jié)合劑中對水化作用有著明顯的催化作用。</p><p>　　氫氧化鈣的消耗和稀釋效果

50、等促進了水化作用。這種對水化作用的促進，在加入濃縮硅粉時表現(xiàn)的最強烈，在加入面粒化高爐礦渣時表現(xiàn)一般，在加入粉煤灰是表現(xiàn)的比較弱。</p><p>　　在缺少一個更可靠的熱率曲線來描述含輔助膠凝材料的混凝土?xí)r，人們提出了模型方程。</p><p><b>　　參考文獻：</b></p><p>　　1. Ballim Y, Graham PC

51、(2003) A maturity approach to therate of heat evolution in concrete. Mag Concr Res 55(3).doi:10.1680/macr.55.3.249.37571</p><p>　　2. Koenders EAB, van Breugel K (1994) Numerical andexperimental adiabatic hyd

52、ration curve determination. In:Springenschmid R (ed) Thermal cracking in concrete atearly ages. E&FN Spon, London</p><p>　　3. Maekawa K, Chaube R, Kishi T (1999) Modelling of concrete performance. Spon P

53、ress, London</p><p>　　4. Gibbon GJ, Ballim Y, Grieve GRH (1997) A low cost,computer-controlled adiabatic calorimeter for determining the heat of hydration of concrete. ASTM J Test Eval 25(2):261–266</p>