الفهرس 
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Abstract
Various mixes are prepared using a mixture of liquid sodium silicate and sodium hydroxide as alkaline activator solution with fixed ratio of 2.5 and the concentration of sodium hydroxide is 10 Molar. The pastes are moulded into 1 inch cubic moulds and left within the moulds at 100% relative humidity for 24 hours, then demoulded and cured under tap water for 3,7,28,56 and 90 days. The hydration characteristics of the different mixes have been tested via determination of the setting time, compressive strength, chemically combined water content, bulk density, total porosity and XRD analysis at different time, in order to study the effect of some artificial pozzolana such as ground granulate blast furnace slag (GGBFS), cement kiln by-pass dust (CKD), fly ash (FA) and calcium hydroxide on metakaolin geopolymer binders. After 28 days of curing under tap water the cubes are divided into 3 parts which used in the following curing modes:
One of the hardened pastes was cured under tap water to continue hydration at the remaining time intervals.
Another specimen was immersed in 5% MgSO4 solution to investigate the resistivity against sulfate attack at 3, 7, 28, 56 and 90 days. The aggressive solution was renewed monthly to maintain constant concentration.
Last set of specimens were subjected to different elevated temperature 200°C, 400°C, 600°C and 800°C in an electrical furnace with a heating rate 10°C/min, a hold time of 1hour, and then were cooled at ambient temperature to determine the residual compressive strength.
The main conclusions could be derived from this investigation are summarized as follows:
1- Alkali Activated MK- CKD:
• All mixes with CKD (MD20, MD30 and MD40) cured in water showed higher compressive strength compared to blank mix (M0).
• The mix contain 20% CKD give the optimum value of compressive strength than other mixes
• Chemically combined water contents of the alkali activated MK-CKD pastes gradually increases up to 90 days.
• The bulk density of all mixes increases up to 90 days.
• The total porosity decrease with curing time and the mix contain 20% CKD give the lower value of total porosity.
• In sulfate mix MD20 retained high values of compressive strength than other mixes as well as the blank mix (M0).
• Chemically combined water contents of all the blended mixes were higher than those of the blank mix
• Chemically combined water contents of all MK-CKD pastes cured in sulfate solution were higher than those cured in water.
• X-ray diffraction analysis showed that the main phases of the hydration products C-S-H and C-A-S-H were formed.
• After subjected to elevated temperature all mixes suffered from reduction in compressive strength from room temperature until 400oC due to expel of water.
• At 800 oC the mix contain 20% CKD gives the higher value of compressive strength due to the viscous sintering process.
2- Alkali Activated MK – GGBFS:
• All mixes with GGBFS (MS20, MS30 and MS40) cured in water showed higher compressive strength compared to blank mix (M0).
• The mix contain 40% GGBFS give the optimum value of compressive strength than other mixes
• Chemically combined water contents of the alkali activated MK- GGBFS pastes gradually increases up to 90 days.
• The bulk density of all mixes increases up to 90 days.
• The total porosity decrease with curing time and the mix contain 40% GGBFS give the lower value of total porosity.
• In sulfate mix MS40 retained high values of compressive strength than other mixes as well as the blank mix (M0).
• Chemically combined water contents of all the blended mixes were higher than those of the blank mix
• Chemically combined water contents of all MK- GGBFS pastes cured in sulfate solution were higher than those cured in water.
• X-ray diffraction analysis showed that the main phases of the hydration products C-S-H and C-A-S-H were formed..
• After subjected to elevated temperature all mixes suffered from reduction in compressive strength from room temperature until 400oC due to expel of water.
• At 800 oC the mix contain 20% GGBFS gives the higher value of compressive strength due to the viscous sintering process.
3- Alkali Activated MK – CH:
• All mixes with CH (MC20, MC30 and MC40) cured in water showed higher compressive strength compared to blank mix (M0).
• The mix contain 20% CH give the optimum value of compressive strength than other mixes
• Chemically combined water contents of the alkali activated MK- CH pastes gradually increases up to 90 days.
• The bulk density of all mixes increases up to 90 days.
• The total porosity decrease with curing time and the mix contain 20% CH give the lower value of total porosity.
• In sulfate all mix show increase in compressive strength up to 28 days followed by significant reduction.
• X-ray diffraction analysis showed that the main phases of the hydration products C-S-H and C-A-S-H were formed and the formation of portlandite.
• After subjected to elevated temperatures all mixes suffered from reduction in compressive strength from room temperature until 400oC due to expel of water.
• At 600 oC all mixes showed gained in strength due to further polymerization of un-reacted particles
4- Alkali Activated MK – FA:
• All mixes with FA (MF20, MF30 and MF40) cured in water showed higher compressive strength compared to blank mix (M0).
• The mix contain 40% FA give the optimum value of compressive strength than other mixes
• Chemically combined water contents of the alkali activated MK- FA pastes gradually increases up to 90 days.
• The bulk density of all mixes increases up to 90 days.
• The total porosity decrease with curing time and the mix contain 40% FA give the lower value of total porosity.
• In sulfate all mix show increase in compressive strength up to 28 days followed by significant reduction.
• X-ray diffraction analysis showed that the main phases of the hydration products C-S-H and C-A-S-H were formed and the formation of mullite.
• After exposure to elevated temperature all mixes suffered from reduction in compressive strength from room temperature until 800oC due to crystallization and formation of nepheline phase.