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Abstract  

This paper reports an investigation of the effect of the particle size of kaolin on its transformation to metakaolinite. Kaolin from the island of Milos was either crushed or ground in order to produce four samples with different degrees of fineness (residue at 500 m: 0–71.8%). The samples were treated thermally under different conditions in order to determine the optimum treatment conditions. The conversion of kaolinite to metakaolinite and the structural changes in the material during treatment were investigated by means of TG and XRD, respectively. Each sample was incorporated into a type I cement, at 20% by mass of cement, and the compressive strengths of the resulting blended cements were measured. It is concluded that the particle size of the raw kaolin does not affect the thermal conversion or the pozzolanic activity of the material. The use of crushed kaolin has many benefits since the furnace load can be increased, while the grinding process is needed only to reduce the size of the metakaolinite particles.

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Abstract  

Sulphate resistance and passivation ability of the mortars made from pozzolan cement of CEM IV/A (P) type according to European Standard EN 197-1 (zeolite blended cement with 60.82 mass% of PC clinker, 35.09 mass% of zeolite and 4.09 mass% of gypsum abbreviated as ZBC) and ordinary Portland cement (abbreviated as PC) are introduced. Resistance tests were performed in water and 5% sodium sulphate solution (both 20°C) for 720 days. The increased sulphate resistance of pozzolan cement relative to that of PC was found. The key quantitative insight into the hydrate phase behaviour is given by thermal analysis. This is due to pozzolanic reaction of zeolite with PC resulting in reduction of the formed Ca(OH)2 opposite to the reference PC. Ability of pozzolan cements with 15 to 50 mass% of zeolite to protect steel against corrosion was verified in 20°C/85% RH-wet air within 180-day cure. Steel was not corroded in the mortars made with pozzolan cement containing up to 35 mass% of zeolite. Pozzolan cement of CEM IV/A (P) type containing 35 mass% of zeolite is a suitable cementitious material for concrete structures exposed to sulphate attack. Steel is protected against corrosion by this pozzolan cement in the same measure as the reference PC.

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Self-compacting concrete has gained a wide range of applications as a result of its unique properties, which can offer high strength and durable type of concrete with the proper selection of the raw materials. The purpose of this study was to show the effect of the use of high dosage of air entraining admixture on the properties of self-compacting concrete. An experimental investigation on the frost-salt scaling resistance of conventional and air entraining selfcompacting concrete incorporating slag-blended cement and supplementary cementitious materials was carried out. Further fresh and hardened properties tests including slump flow, V-funnel, compressive strength, splitting tensile strength, air void characteristics and water absorption tests were performed to obtain an objective evaluation between air and non-air entrained self-compacting concrete mixtures. Air void characteristics were evaluated through the automated image analysis procedure to enrich this investigation. Results indicate the following: the air entraining admixture highly decreased the compressive strength up to 52% and the metakaolin was the governing supplementary cementitious material concerning the scaling resistance and water absorption in comparison with the silica fume.

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degree can be more easily determined and is calculated as the heat released at a certain moment Q ( t ) relative to the maximum heat release Q max [ 14 ]. Pane and Hansen [ 21 ] also affirmed the suitability of the method for blended cements. Moreover

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-5533.0000083 . 4. Tongsheng Z , Qijun Y , Jiangxiong W , Peng G , Pingping Z . Study on optimization of hydration process of blended cement . J Therm Anal Calorim . doi: 10.1007/s10973

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blended cements, impart similar behaviour to that of commercial metakaolin especially with respect to cement strength development, setting times and hydration as well as durability [ 32 ]. The similar kaolins with relatively poor kaolinite content are in

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Journal of Thermal Analysis and Calorimetry
Authors: Carolina Resmini Melo, Elidio Angioletto, Humberto Gracher Riella, Michael Peterson, Márcio Roberto Rocha, Aline Resmini Melo, Luciano Silva, and Susane Strugale

.02.009 . 11. Frías M , Rodrígues O , Vegas I , Vigil R . Properties of calcined clay waste and its influence on Blended cement . J Am Ceram Soc. 2008 . doi: 10.1111/j.1551-2916.2008.02289.x

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granulated blast-furnace slag on some properties of pastes, mortars, and concretes Frohnsdorff , G , eds. Blended cements, ASTM STP 897 . Philadelphia : American Society for Testing and Materials ; 1986 29 – 47 . 10.1520/STP36390S

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, Perraki , T , Tsivilis , S , Kakali , G . Zeolite blended cements: evaluation of their hydration rate by means of thermal analysis . J Therm Anal Calorim . 2009 ; 96 : 993 – 998 . 10.1007/s10973-009-0056-x . 9

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blended cement mortars containing nano-metakaolin at elevated temperatures ,” Construct. Build. Mater. , vol. 35 , 900 – 905 , October 2012 . 10.1016/j.conbuildmat.2012.04.099 [39] R. M. S. Morsy and El-Nouhy A. M. , “ Effect of elevated

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