1、 PDF外文：http:/ The Hydration of Blended Cement at Low W/B Ratio ABSTRACT： The hydration process,hydration product and hydration heat of blended cement paste mixed with mineral admixture and expansive agent at Low/B ratio are studied Byrd,Thermos analysis,and calorimetry instr
2、ument,and they were compared with those impure cement paste.The results show that pure cement and blended cement at Low/B ratio havethe same types hyperproductions,but respective amounts hyperrational products of various blended cements at same ages Anthea variation Olathe amount of same hydration w
3、ith ages are different；The joint effect liquefaction fodgel-deterring due to water absorption and the expansive pressure on millepore adrift caused Sotheby crystallogenetic is the impetus of the volume expansion cementa paste,and Rothermere effect is much greater than the latter one. KEY WORDS
4、: hydration； blended cement； low W/B ratio； expansion mechanism 1Introduction The hydration and hardening processes of ordinary cement have been studied intensively1-3.Partly replacing cement with fly ash,slag,or other active mineral admixture can not commodify the cement strength grade,
5、reduce the hydration heat of cement,but also meliorate the structure of harden cement paste4.Applying expansive agent in ordinary concrete can combine the bearing and waterproof functions of a building,and it can also reduce the shrinkage and prevent the cracking of concrete5,6.However,the hydration
6、 process of cement mixed with fly ash,slag and expansive agent at Low/B ratio under non-saturation water condition need to be studied sufficiently.So we execute the research work in this field. 2Elementarily 2.1Raw materials (1)Cement:Grade 42.5 P O cement produced by Huitai
7、n Cement Company in China was used. (2)Fly ash: Ground fly Ashdown produced by a thermoelectricity plant. (3)Slag:Ground blast furnace slag was produced by Wu Han Steel Company in China whose specific surface is 6000cm2/g. (4)Expansive agent:(a)UEA expansive agent was manufactured by Zhengzhou
8、 Company,The chemical compositions of raw materials are shown in Table 1.(b) Two kinds of expansive grandparental prepared by ourselves；The main components expansive agent ar raw alunite and CaSO42H2O and those expansive agent include autunite,clinker and sulphonate cement CaSO42H2O. 2.2Method
9、 2.2.1 Preparation of cement paste sample under breeching condition The pure cement paste (or cement paste mixed with mineral admixture and expansive agent) was prepared in 202020mmmould.The specimen Demopolis after 24h of standard curing(20 ,RH905%),and then cured without molds under th
10、e same condition to test ages. 2.2.2 Measuring the hydration heat of cement paste A Dardans bland XMD50000 series intellective instrument and a standard Cu-Thermos resistance temperature sensor were used.The temperature measuring range was -50 to 150 .After being mixed evenly,the cement paste.
11、Sample was put into the round vacuum flask,and the temperature sensor was embedded into the cement paste,sealing the mouth of the flask with PVC lamina and olefin and continuously measuring the temperature variation of the cement paste at 20 environment temperature until the temperature of cement pa
12、ste is the wherewithal of environment temperature. 3 Results and Discussion 3.1 Hydration process of blended cement We used 15% fly ash,15% flag and 10% UEA to replace correspondency cement,and studied the hydration products with XRD.The specimens were all molded and cured u
13、nder free,Low/B ratio (0.28) and moist conditions (but not soaked into water).From Fig.1 to Fig.4 we can learn that the types of the hydration products of pure cement and blended cement are the same.All of them are C-S-H,CH,Aft etc.In addition,there hemihydrated C3S and C2Setc.But in the same hydrat
14、ion age,the amount of all kinds of hydration products differs obviously.And this fact is reflected in the differences of the relative integrity of the diffraction peaks (Counterseal-e).We list the relative intensity of the diffraction peaks of the main hydration products and hydrated C3S and C2S at ages of 3d and 28d age in Table 2. Table1 Characteristics of Raw Materials SS:Specific surface；R W D:Ratio of water demand；R28:Compressive strength of 28d Table2 The Relative Intensity of the Diffraction Peaks/Counts
