الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The need to reduce the consumption of energy and the release of CO2 is recognized in the Portland cement industry and much effort or resources have been expanded in improving the traditional manufacturing processes. So, there are important needs to resolve the ecological and economical problems to solve ordinary Portland cement problems like sulfate, chloride and sea water attack. At recyclization of solid wastes as GBFS, FA, SF and CKD, these wastes exposed to obtain binder materials characterized by resistance to aggressive media, cheaper and more friendly to environment than Portland cement. Different mixes were prepared from GBFS, SF, FA and CKD using SH and SSL as alkaline activator. The mixing of the pastes were carried out in a porcelain mortar for 3 minutes with the required amount of water containing the activator until workability is attained. The pastes were moulded in the 0.5x0.5x0.5 cm moulds and cured in humidifier (100% R.H.) at room temperature for 24 hours then demoulded; and cured in 100% relative humidity up to 90 days. Compressive strength, bulk density and electrical conductivity combined water and combined slag contents as well as total porosity were measured. The hydration products of some selected samples were identified by IR, XRD, DTA/TG and SEM technique. The main conclusions could be derived from this investigation are summarized as follows: 1. Alkali Activation of GBFS: • Electrical conductivity of alkali activated GBFS depends mainly on the binder composition, the activator type and its concentration. Alkali activator contents affected the location and intensities of the conductivity maximum. • Mix S6 shows the higher of compressive strength at all curing times . • The improvement of compressive strength is related to the reorganization in the microstructure of alkali activated GBFS system. 2. Alkali activated GBFS-SF pastes: • GBFS-SF mixes show a sharp decrease in electrical conductivity maxima during hydration periods. The presence of 2 mass% SF shows a slight shift of electrical conductivity maxium peaks to longer hydration time. • The combined water contents of mix SSF2 gives higher values at all curing ages. • The combined slag content increases with SF up to 4 mass%. • Mix SSF1 shows the higher compressive strength at all curing ages. The increase of compressive strength is due to higher pozzolanic activity of SF and its as nucleating agents or as a seeding for formation of C-S-H gel. 3. Physico-chemical and mechanical characteristics of GBFS-FA: • Increase of the amount of substitution of FA up to 30 mass % , increases the electrical conductivity and shows a higher maxima. • Mix SFA1 has a higher values of chemically combined water contents. • Both of combined slag and combined water contents of alkali activated GBFS-FA are lower than those of GBFS pastes. • The mix containing 20 mass% FA have higher compressive strength at all curing ages. • Substitution of GBFS with FA decreases the bulk density. • The total porosity of alkali activated GBFS-FA are higher than that of the alkali activated GBFS. 4. Alkali activation of GBFS-FA-SF: • The conductivity of all mixes containing FA and SF have a lower conductivity values than those of neat GBFS paste. • Mix SFASF1 shows a sharp decrease of the electrical conductivity after 100 min than the other mixes, due to the formation and accumulation of more hydrated products. • The combined water of mix SFASF1 shows higher values, due to the formation a C–(A)–S–H and N–A–S–(H) geopolymer gel. • Mix SFASF1 shows the higher combined slag contents. • The compressive strength of alkali activated GBFS-FA-SF that containing 20 mass% FA and 4 mass% SF have a higher compressive strength. • Increase of FA up to 30-50 mass%, the compressive strength decreases. 5. Substitution of GBFS with cement kiln dust: • CKD affects the location and height of the conductivity peaks, which decreases the height of conductivity maximum, and shifts to a short time. • Mix SCKD4 shows the higher values of combined water, due to the formation of excessive amounts of the C-S-H, sulphoaluminate hydrated products having higher lime and water contents. • 20 mass% CKD in alkaline GBFS-CKD mixes gives higher values of compressive strength. • The compressive strength decreases slightly with CKD content, this is due to high alkalis content in CKD that gives more sulphoaluminate and chloroaluminate hydrate with low strength. • Addition of 20 mass% CKD the bulk density increases, and gives lowest total porosity. 6. Activation of GBFS-CKD-SF binders: • SCKDSF1 paste shows the high conductivity. • SCKDSF4 gives the higher chemically combined water, due to the formation of sulphoaluminate and chloroaluminate hydrates. • Mix SCKDSF1 shows a high combined slag contents, due to that the SF acts as a nucleating agent which activates the hydration of GBFS-CKD-SF. • Mix SCKDSF1 leads to an improvement in strength as compared with that of mixes GBFS-CKD-SF at all ages of hydration. • Mix SCKDSF1 shows a lower total porosity and higher bulk density due to formation of more hydration products. 7. Aggressive chemical attack: • The compressive strength of mix S1 shows higher values, due to a good pozzolanic activity in alkaline activation that exhibits higher resistance to sulphate medium up to 180 days. • Alkali activated GBFS leads to good durability and high resistance to chemical attack.