Effect of Polycarboxylate Superplas

Effect of Polycarboxylate Superplasticizer on Properties of Calcium
2 Aluminate Cement Mortar
3 Neven Ukrainczyk
4 Faculty of Chemical Engineering and Technology, University of Zagreb, Marulicev trg
5 19, 10 000 Zagreb, Croatia (e-mail: [e-mail])
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7 Abstract
8 The effect of polycarboxilate ether (PCE) based superplasticizer onto the fresh and hardened
9 properties of calcium aluminate cement (CAC) based materials was investigated. Cohesion of
10 the fresh mortar was improved by addition of methyl-cellulose, thus avoiding segregation
11 induced by the superplasticiser action. As PCE significantly retarded the setting time, Li2CO3
12 was investigated as an accelerator by calorimetric measurements. Compressive and flexural
13 strengths, porosity and dynamic modulus were tested after 1 day and 9 days cured at 23 °C
14 and after transformation of metastable hydration products to stable ones at 60 °C. The
15 combined usage of PCE with methyl-cellulose and Li2CO3 showed promising
16 superplasticizing properties for CAC that improved properties of the material.
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18 Keywords: Calcium aluminate cement, calorimetry, hydration kinetics, mechanical
19 properties, rheology, setting time, superplasticizer.
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21 1. Introduction
22 Calcium aluminate cement (CAC) is a special cement with many specific applications
23 (Bensted, 2002; Robson, 1962; Fentiman et al., 2008; Scrivener et al., 1998, 1999) mainly
24 attributed to it’s rapid hardening (Ukrainczyk, 2010; Ukrainczyk et al., 2013, 2012; Sipusic et
25 al., 2013; Gosselin et al., 201 0) and excellent resistance to chemical attack, fire, abrasion and
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26 impact (Scrivener et al.,). CACs are favorably used in cryogenic areas, such as the loading
27 docks of liquid-gas plants, because of the excellent thermal shock resistance. Furthermore
28 CAC is an excellent material for encapsulation of toxic wastes (Ukrainczyk et al., 2012;
29 Navarro-Blasco et al., 2013). CAC harden rapidly with high early strengths even under
30 freezing temperatures, if protected from freezing prior to initial set. The hydration process of
31 other types of cements (e.g. Portland cement, PC) is greatly slowed or even stopped at such
32 low temperatures. The rapid hardening characteristic of CAC makes it suitable to put a
33 cement based lining (e.g. floor or highway and bridge deck repair patch (Ukrainczyk and
34 Rogina, 2013; Ukrainczyk et al., 2013; Sipusic et al., 2013; Justnes, 2008)) back in service
35 within a few hours. The ultra-rapid setting CAC based materials, which set within a few
36 minutes, can be readily obtained by a very small addition of Li salts (Ukrainczyk and Rogina,
37 2013; Ukrainczyk et al., 2013; Sipusic et al., 2013; Gosselin et al., 2010). Time for concrete
38 repair and retrofitting may become a critical consideration for a structure where the costs and
39 disruption of its remaining out of service can have a significant impact on the operation.
40 Compared to PC, the general kinetic difference in CAC hydration, is that the hydration
41 products do not form an initial film barrier on the surface of anhydrous cement grains, as in
42 calcium silicate (i.e. PC) hydration, but precipitate in water-filled pores homogenously
43 (Lamour et al, 2001; Ukrainczyk, 2010). This through-solution (homogenised crystallisation)
44 mechanism is responsible for the unhindered hydration process and the resulting rapid
45 hydration evolution after the massive nucleation process. During the hydration of CAC, a
46 large quantity (typically 70–90% (Ukrainczyk, 2010)) of total heat is liberated in a short
47 period (the first 24 h) that could cause a considerable increase in material temperature
48 (Ukrainczyk and Rogina, 2013; Ukrainczyk and Matusinović, 2010).
49 The use of CAC is limited by the high price and adverse effects of concrete properties such as
50 a reduction of strength. The hydration of CAC is highly temperature dependent, yielding
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51 morphologically and structurally different hydration products that continuously alter the
52 material properties (Ukrainczyk and Rogina, 2013; Ukrainczyk and Matusinović, 2010;
53 Gosselin et a., 2010). In contrast, PC hydration has a much less pronounced temperature
54 dependency. Setting and hardening of CAC is primarily due to the hydration of CA (cement
55 notation: C - CaO, A - Al2O3, F - Fe2O3, S - SiO2, H - H2O), but other compounds also
56 participate in the hardening process especially in long-term strength development (Bensted,
57 2002). The hydration of CAC yields CAH10 as main products at temperatures less than 20oC,
58 C2AH8 (Ukrainczyk et al., 2007) and AH3 at about 30oC, and C3AH6 and AH3 at temperatures
59 higher than 55oC. CAH10 and C2AH8 are known to be metastable at ambient temperature and
60 convert to the more stable C3AH6 and AH3 that have higher density thus resulting in increase
61 of material porosity and permeability and a loss of strength (Bensted, 2002; Scrivener and
62 Capmas, 1998; Gares, 1997). The transformation is accelerated by temperature and moisture
63 availability for the dissolution and re-precipitation processes to take place. It has to be taken into
64 account because collapses of CAC concretes in different countries have led to disasters and its
65 use is forbidden for structural applications due to the strength regression and the quick
66 carbonation which leads into premature reinforcement corrosion. The w/c and the amount of
67 the main (active) minerals in CAC are the principal variables governing the porosity and
68 strength development during the transformation reactions (Bensted, 2002). This is because the
69 free water is released by transformation reactions (metastable hydrates contain more water
70 than the stable ones) which contributes to a further hydration of non-hydrated cement that
71 further fills the porosity. Thus, the deleterious effect of the transformation reactions on
72 properties of CAC based materials could be reduced by lowering of the w/c. Earlier
73 construction failures in the history of CAC concrete emphasized that a design must be on the basis
74 of the transformed properties (primarily strength) and the limits on the w/c (

Kết quả (Việt) 1:

Tác dụng của Polycarboxylate Superplasticizer trên các sản phẩm canxi2 aluminat vữa3 Neven Ukrainczyk4 khoa kỹ thuật hóa học và công nghệ, đại học Zagreb, Marulicev trg5 19, 10 000 Zagreb, Croatia (email: [e-mail])67 tóm tắt8 tác dụng của polycarboxilate ête (PCE) dựa superplasticizer lên tươi và cứng9 thuộc tính của canxi aluminat xi măng (CAC) dựa trên vật liệu được điều tra. Gắn kết của10 vữa tươi đã được cải thiện bằng cách thêm methyl-cellulose, như vậy tránh phân biệt11 gây ra bởi các hành động superplasticiser. Như PCE đáng kể chậm thời gian thiết lập, Li2CO312 được điều tra như là một máy gia tốc của calorimetric đo đạc. Nén và flexural13 thế mạnh, độ xốp và mô đun năng động đã được thử nghiệm sau ngày 1 và 9 ngày, chữa khỏi ở 23 ° C14 và sau khi chuyển đổi của sản phẩm hydrat hóa đồng phân với ổn định những người ở 60 ° C. Các15 kết hợp sử dụng của PCE với methyl-cellulose và Li2CO3 đã cho thấy hứa hẹn16 superplasticizing tài sản cho CAC có cải thiện các tính chất của vật liệu.1718 từ khóa: canxi aluminat xi măng, calorimetry, hydrat hóa động học, cơ khí19 thuộc tính, lưu biến, thiết lập thời gian, superplasticizer.2021 1. Giới thiệu22 canxi aluminat xi măng (CAC) là một xi măng đặc biệt với nhiều ứng dụng cụ thể23 (Bensted, 2002; Robson, năm 1962; Fentiman et al., năm 2008; Scrivener et al., 1998, 1999) chủ yếu là24 do nó là nhanh chóng cứng (Ukrainczyk, 2010; Ukrainczyk et al., 2013, năm 2012; Sipusic et25 al., 2013; Gosselin et al., 201 0) và sức đề kháng tuyệt vời để tấn công hóa học, cháy, mài mòn vàVăn bản chínhClick vào đây để tải về các văn bản chính: Ukrainczyk_pce_cac_Revised.doc 1 2 3 4 5 6 7 8 9101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646526 tác động (Scrivener và ctv.,). CACs được sử dụng thuận lợi trong khu vực đông, chẳng hạn như nạp27 bến cảng của nhà máy chất lỏng-khí, vì kháng cự tuyệt vời sốc nhiệt. Hơn nữa28 CAC là một vật liệu tuyệt vời để đóng gói các chất thải độc hại (Ukrainczyk et al., năm 2012;29 Navarro-Blasco et al., 2013). CAC cứng nhanh chóng với thế mạnh đầu cao thậm chí nhỏ hơn30 nhiệt độ, đóng băng nếu bảo vệ từ đóng băng trước khi thiết lập ban đầu. Quá trình hydrat hóa31 các loại xi măng (ví dụ: xi măng Portland, PC) rất chậm lại hoặc thậm chí ngừng như vậy32 nhiệt độ thấp. Đặc tính nhanh chóng cứng của CAC làm cho nó thích hợp để đặt một33 xi măng dựa niêm mạc (ví dụ như sàn hoặc đường cao tốc và cầu sàn tàu sửa chữa vá (Ukrainczyk vàRogina 34, 2013; Ukrainczyk et al., 2013; Sipusic et al., 2013; Justnes, 2008)) trở lại trong dịch vụ35 trong vòng một vài giờ. Các thiết lập cực kỳ nhanh chóng CAC dựa trên vật liệu, thiết lập trong vòng một vài36 minutes, can be readily obtained by a very small addition of Li salts (Ukrainczyk and Rogina,37 2013; Ukrainczyk et al., 2013; Sipusic et al., 2013; Gosselin et al., 2010). Time for concrete38 repair and retrofitting may become a critical consideration for a structure where the costs and39 disruption of its remaining out of service can have a significant impact on the operation.40 Compared to PC, the general kinetic difference in CAC hydration, is that the hydration41 products do not form an initial film barrier on the surface of anhydrous cement grains, as in42 calcium silicate (i.e. PC) hydration, but precipitate in water-filled pores homogenously43 (Lamour et al, 2001; Ukrainczyk, 2010). This through-solution (homogenised crystallisation)44 mechanism is responsible for the unhindered hydration process and the resulting rapid45 hydration evolution after the massive nucleation process. During the hydration of CAC, a46 large quantity (typically 70–90% (Ukrainczyk, 2010)) of total heat is liberated in a short47 period (the first 24 h) that could cause a considerable increase in material temperature48 (Ukrainczyk and Rogina, 2013; Ukrainczyk and Matusinović, 2010).49 The use of CAC is limited by the high price and adverse effects of concrete properties such as50 a reduction of strength. The hydration of CAC is highly temperature dependent, yielding 1 2 3 4 5 6 7 8 9101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646551 morphologically and structurally different hydration products that continuously alter the52 material properties (Ukrainczyk and Rogina, 2013; Ukrainczyk and Matusinović, 2010;53 Gosselin et a., 2010). In contrast, PC hydration has a much less pronounced temperature54 dependency. Setting and hardening of CAC is primarily due to the hydration of CA (cement55 notation: C - CaO, A - Al2O3, F - Fe2O3, S - SiO2, H - H2O), but other compounds also56 participate in the hardening process especially in long-term strength development (Bensted,57 2002). The hydration of CAC yields CAH10 as main products at temperatures less than 20oC,58 C2AH8 (Ukrainczyk et al., 2007) and AH3 at about 30oC, and C3AH6 and AH3 at temperatures59 higher than 55oC. CAH10 and C2AH8 are known to be metastable at ambient temperature and60 convert to the more stable C3AH6 and AH3 that have higher density thus resulting in increase61 of material porosity and permeability and a loss of strength (Bensted, 2002; Scrivener and62 Capmas, 1998; Gares, 1997). The transformation is accelerated by temperature and moisture63 availability for the dissolution and re-precipitation processes to take place. It has to be taken into64 account because collapses of CAC concretes in different countries have led to disasters and its65 use is forbidden for structural applications due to the strength regression and the quick66 carbonation which leads into premature reinforcement corrosion. The w/c and the amount of67 the main (active) minerals in CAC are the principal variables governing the porosity and68 strength development during the transformation reactions (Bensted, 2002). This is because the69 free water is released by transformation reactions (metastable hydrates contain more water70 than the stable ones) which contributes to a further hydration of non-hydrated cement that71 further fills the porosity. Thus, the deleterious effect of the transformation reactions on72 properties of CAC based materials could be reduced by lowering of the w/c. Earlier73 construction failures in the history of CAC concrete emphasized that a design must be on the basis74 of the transformed properties (primarily strength) and the limits on the w/c (