الفهرس 
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Abstract
The issue of solid waste management of various kinds of hazardous wastes (industrial, agricultural, household, .... etc) is one of the most serious issues facing environmental management in Egypt and the seriousness of this issue derives from the sheer size of this waste and increasing year after year.
The diversity of these residues and the different components and sources and the potential lack of hardware-based management for the full absorption of the waste and the consequent large accumulations become a more serious problem facing localities and devices require huge efforts to get rid of them and reuse them.
In this investigation some solutions to the problem of the accumulation of industrial wastes, including the hazardous solid waste generated from the cement industry, known as cement kilns dust (CKD); since lag about 6% of the total cement production in Egypt, where the production of about 64 million tons annually of cement leads to generation of about 5 million tons annually of cement kiln dust. This study presents other solution to the problem of another industrial waste, including the industrial solid waste resulting from the manufacture of acetylene gas which is
CHAPTER: 5 [SUMMERY AND CONCLUSIONS]
rich in lime residues (LRS) where about 10 factories in Egypt generate behind them 500 tons per year of lime rich sludge (LRS) .
These two solid wastes (LRS and CKD) were utilized as activators for kaolinite sand (KS) produced from the purification of kaolin clay .
The following results are concluded:
A: Physio-chemical and mechanical properties of
KS-LRS pastes
1 - The results showed that the compressive strength values of the hardened paste made of 90% kaolinite sand (KS) - 10% lime blend rich sludge (LRS) are relatively higher than those of the paste made of 80% kaolinite sand (KS) - 20% lime rich sludge (LRS) blend at all ages of hydration.
2 - The amount of free lime contents of the paste made of 80% kaolinite sand (KS) -20% lime rich sludge (LRS) blend are higher than those of the paste made of 90% kaolinite sand (KS) - 10% lime rich sludge (LRS) blend .
3- The amount of chemically combined water of the paste made of 90% KS - 10% LRS blend are lower than those of the paste made of 80% KS - 20% LRS blend .
CHAPTER: 5 [SUMMERY AND CONCLUSIONS]
4- The FTIR and TGA/DTG analyses showed that the amount of calcium silicate hydrates (CSH) and calcium alumino-silicate hydrates (CASH) increase with the increase of curing time. The results showed also that the amounts of CSH and CASH of the paste made of 90% KS-10%LRS are greater than those of the paste made of 80%KS-20% LRS.
B: Physico-chemical and mechanical properties of
KS-CKD pastes
1 – The compressive strength of the pastes made of KS-CKD blends increases with increasing amount of CKD up to 30% at all ages of hydration.
2 – The study proved that there are no residual free lime content of the hardened pastes made of 95% KS – 5% CKD and 90% KS – 10% CKD blend from 1 up to 28 days of curing in tap water. On the other side, the free lime contents of the pastes made of 80 % KS – 20 % CKD and 70 % KS – 30 % CKD are relatively high at the early ages of hydration but totally consumed at the later ages of curing up to 28 days.
The amounts of chemically combined water increase with increasing proportion of CKD from 5% up to 30% in KS-CKD blends .
4 – The results of FTIR and TGA/DTG analyses are in agreement with the results of compressive strength, chemically combined water and free lime contents.
from the previous results, We can recommend the utilization of kaolinite sand, cement kiln dust and lime rich sludge to produce low cost, economic and environmentally friendly blended cements which possess improved physico-chemical and mechanical properties.