外文翻譯--新mx外加劑對混凝土耐久性的影響(英文）

1、Vol. 20 No. 1 Journal of Wuhan University of Technology - Mater. ~i. Ed. Mar. 2005 Influences of a New Admixture MX on Concrete Durability * MA Baoguo DONG Rongzhen ZHU Hongbo ZHANG Li ZHONG Kaihong HE Xingyang LI

2、 Zongjin (Key Laboratory of Silicate Materials Science and Engineering,Ministry of Education, Wuhan University of Tedmotogy,Wuhan 430070, China) Abstract: The peoCommnce of concrete, with a new admixture MX was studie

3、d by using the freeze- thaw cy- cle, permeability and chemical attack test. The experimental results show that MX inzprovas the durability of con- crete. Within the optimum proportion ranges fiom O. 1% to 1%, the com

4、pressive strength of concrete after freeze, thaw is increased t 9“ 20%- 50% , and Young' s modulus can be increased by 3.76- 5.64 times. The, strength and weight/o,gs of concrete with O. 4% MX are respectively de

5、creused by 28% and 60% after hydroch/or/c ac/d attack. The strength and weight lo,gs of concrete with O. 4% MX are decreased t 9“ 5%- 20% qfter sulfuric acid and sodium sulfate attack. The permeability of concrete w

6、hh 1% MX at 28 days can be decreased by more than 30% . The im~e, stigation of the negative temperature property of MX and analysis on concrete composition and microstructure by MIP re~eal that the heat conductum is re

7、sisted and the freezing procedure of solution in concrete pore is retarded due to the adding of MX. More~wer , the pore structure of concrete, with MX is improved, thus impr(wing the dura- bility. 13a~ed on this stud)&

8、#39;, a resistantv nuMel of MX to block the heat and ma~ transference was proposed, and the mechanism of durability improtement of concrete with MX u~ explained. Key words: MX durability admixture; ratio of strength/o

9、ss; negative, temperature property 1 Introduction Now people pay more attention to the study on the durability of concrete in severe environment. A lot of new admixtur~ with different functions, meeting the require-

10、ment for durability in different environment, have been de- veloped successfully ~'2~ . But these new admixtures only aimed at some special durability of concrete. So their ap- plications in engineering are limited.

11、 It is significant to develop a new chemical admixture with lower cost and high performance (improving the comprehensive durability of concrete ), especially for Western development and Qinghai - Xizang railway construct

12、ion of China ~ 3 1. Studies on the ancient buildings and structures such as Nanjing and Hezhou ancient wall, Dalian ancient bat- tery, Fujian ancient red soil fortified villages, show that tung oil, polished glutinous r

13、ice fluid and carambola vine liquid added to lime sand mortar can increase the durabil- ity of ancient buildings and structures :41 . According to the successful experience in ancient natural plant application and prese

14、nt theoretical knowledge on resin concrete and organic-inorganic cement based composite ~ 5 1, repeated shifting on various natural plant resin was carried out and a new kind of admixture MX for concrete durability was p

15、repared by means of alkali resolution method and hydro- thermal synthesis '6~ . MX is a kind of soluble resin. It is a sticky yellow liquid. Its density is 1.07, surface tension is 6 x 10 -4 N/c~. It is a non-air en

16、training admixture ( lleceive~l: Apr. 20,2004; Accepted: Oct. 23,2004) MA Baoguo( ./-4j./~ ~ ) : Prof. : E-mail: mbgjob@ 163. corn * FuMed by the National “973“ Project(20OlCB610704-3) with water reduction (wat

17、er reduction: 6%-7%). The characteristics of durability enhancer MX were studied in this paper by using freeze-thaw resistance, impermeabili- ty, chemical attack resistance, XRD and MIP. 2 Experimental Raw materi',:

18、ds for experiment is listed as follows: Cement: ASTM type 1 from Hong Kong and from Hua Xin Cement Co. Its physical properties are listed as follows: relative density: 3.15, 3.10; specific surface: 385m 2/kg, 350m 2/kg

19、. Fine aggregate: crushed limestone; max particle size: lOmm; crushing value: 9%; relative density: 2.57. Water: tap water. In order to show the obvious influence of MX on con- crete durability, essential cement/water ra

20、tio of 0.6 is used. In order to make salt crystallization easily form- crystallizing stress inside concrete, cement/water ratio of O. 4 is used for chemical attack experiment. The mixed ratio of concrete is shown in Tabl

21、e 1. 3 Results 3.1 Freeze resistance The freeze resistance of concrete was studied accord- ing to ASTMC666. Freeze-thaw cycle system is: 4 hours at - 20~ 2.5 hours in water at 20~C. Experiment methods: concrete specim

22、ens were made and cured in saturated lime water for 28 days. Three of them were placed into an intelligent freeze-thaw cycle ma- chine for freeze-thaw experiment. The other three of them were placed in air for comparison

23、 experiment. The corn- Vol. 20 No. 1 MA Baoguo et al : Influences of a New Admixture MX on Concrete Durability .... 119 Table 3 Water permeability of specimens with/without MX Reduction rate No Depth of per

24、meability/ram Average/ram if~ depth/% D1 28 30 30 29 - 134 21 19 20 20 30 Experiment results are shown in Table 3. It can be seen from Table 3 that the permeability of concrete is re- duced by 30% and the imp

25、ermeability is obviously im- proved due to the addition of 0.5 % MX. So MX can im- prove the impermeability of concrete. It is hard for water solution with various attack ions to enter the concrete with MX and hardly for

26、 chemical attack to occur. 4 Discussion 4.1 Negative temperature property The freeze-thaw damage to concrete is mainly caused by the solution expansion inside concrete cavity and per- meability pressure of over-cold wa

27、ter transference in ce- mentitious gel pore. The freezing point and temperature reduction property of solution inside concrete cavity have a significant influence on the freezing resistance of con- crete. MX can improve

28、the freezing resistance. The freez- Thermometer “ ~, ~ ~- Thermomet 25 “~ MX5 Flask(46mL)Cover~~ . ~ ~ J ~ 20 l ~ i:i ~:: ~:2~ ~ i ~ 15 Sample solution : Icc+acetonc+sal - : r“Pr~ ~ Mixture ~-C~:-.).

29、I- Cupa : /aOOOmL' / : : ! -lOi Fig.3 Schematic diagram of the test setup ing point of MX solution and the temperature reduction property of MX solution at low temperature are investigat- ed in this paper. The

30、device is shown in Fig. 3. In order to keep the temperature constant, ice, acetone and sodi- tun chloride mixture are used as negative temperature me- dium solution. The freezing point temperature of this solu- tion is -

31、 11.4~ When the ice exists, the negative tem- perature of - 11.4~C can be kept constant. So during the procedure of test, the ice should be kept enough to make the temperature constant. The sample solution is sealed int

32、o the test tube and the initial temperature is recorded. Then the test tube is put in the negative temperature en- vironment. A precise thermometer and a stopwatch are used to monitor the variation of temperature with ti

33、me. The other thermometer is used to monitor whether the tem- perature of negative temperature medium is constant or not. The freezing point and temperature reduction property of 5 % MX solution, 2 % MX solution, 0.5 % M

34、X solution, 5 % NaC1 solution and distilled water are tested in the ex- periment, respectively. The experiment results are shown in Fig. 4 and Fig. 5. 5% Distilled water NaC1 solution 5% 0 300 600 900 Time/s Fig.4

35、The two test results for each of the three groups of specimen solution 25 20 15 lO ~ 5 -5 -10 0 ~%MX 5% Note: The encompassing lee-Acetone-Brine \~ ~ mixture is kept at a temperature of-11.4“12 ~.,.~Distilled wa

36、ter \ ~ epoint for distilled water NaCI s 0 1 u l i o ~ ] 5 ~ ~ 300 600 900 Time/s Fig.5 Temperature depression curves of the solution It is known from Fig. 4 that the temperature reduc- tion property can really

37、reflect the actual property of solu- tion at negative temperature. It is shown from Fig. 5 that the temperature of MX solution reduces more slowly than that of 5% NaC1 solution and distilled water. With the increase of c

38、oncentration of solution, the effect of temper- ature reduction-resistance is more evident. At the one hundred fiftieth second, the temperature of 5 % MX solu- tion is 14~C, and the temperature of NaC1 solution is re- du

39、ced to - 2.1 ~ and the temperature of distilled water is 2%. In view of this, MX can resist heat conduction, prolong the procedure of temperature reduction, and delay the freezing time of solution. It is good for soluti

40、on in concrete cavity transferring to the unfilled space inside concrete, thus lowering the damage to concrete due to freezing of solution in cavity. 4.2 Composition and microstructure analysis The property of materials

41、 depends on the material structure. For cement products, the porosity and pore-size distribution are the main structure characteristics and in- fluence the physical property of concrete greatly. If the quantity of pores

42、over 100ram is reduced, the durability of concrete can be improved greatly iT“sj . In order to analyze the durability mechanism of concrete with MX, pore structures of concrete DI and D4 were tested. The results are sho

43、wn in Fig. 6 and Fig. 7. It can be seen that the pore structure of concrete with 1% MX is obviously differ- ent from that of concrete without MX. For concrete with MX, pores with pore size between 0. lt~m and 10t~m are o

44、bviously reduced, while pores with pore size between lO0l~m and 400I~m have no any change. Analytical results indicate that MX can improve pore size distribution of concrete, reduce the quantity of cavity. The reaction f