Effect of a Synthetically Modified Natural Zeolite Additive on Properties and Durability of Cement Mortars
- Authors: Ikotun, B., Ekolu, S.O. and De Freitas, V.
- Date: 2008
- Subjects: Durabilit , Zeolite , Additive , Cement mortar , Compressive strength
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/61905 , uj:16863 , Citation: Ikotun, B., Ekolu, S.O. and De Freitas, V. (2008), Effect of modified zeolite additive on properties of cement mortars, Proc. 2nd International Civil Engineering Conference on Civil Engineering and Sustainable Development, 23-25 Sept., 2008, Mombasa, Kenya, p.187-196.
- Description: Abstract: Durability characteristics of cement mortars and concrete are of interest to various researchers and practitioners in the field of construction materials engineering. This study evaluated the potential use of a semi-synthetic zeolite additive for improvement of cement mortar properties. The product, a blend of selected alkaloids and zeolite is commercially available and effectively used in soil stabilization for road construction. However, its influence and effectiveness on properties of cementitious systems has not been explored. Emphasis of this study was on durability of cement mortars. This was assessed using the durability index approach being advanced in South Africa. The additive was added to standard mortars of 0.5 water-cement ratio, prepared according to EN 196, in proportions of 0%, 0.4%, 0.6%, 0.8%, 1.0%, and 2.5%. Tests carried out include compressive strength, oxygen permeability, sorptivity and resistance to sulphate attack. It was found that the additive significantly improves durability characteristics while increasing strength and workability when used at optimum proportions. Its use in proportions between 0.4 to 0.6% additive gave optimum results in most tests. Further increase in the additive proportion tends to be counter effective, especially at above 1% additive. The low optimum proportions found also favour economic considerations.
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Sludge to energy recovery dosed with selected trace metals additives in anaerobic digestion processes
- Authors: Matheri, Anthony Njuguna , Ntuli, Freeman , Ngila, Jane Catherine
- Date: 2020
- Subjects: Additive , Anaerobic digestion , Biomethane
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/460010 , uj:40920 , Citation: Matheri, A.N., Ntuli, F. & Ngila, J.C. 2020. Sludge to energy recovery dosed with selected trace metals additives in anaerobic digestion processes.
- Description: Abstract: The energy demand is ever rising with population increase and technology evolution. Coal consumption in South Africa is estimated to be 86% of the total energy demand. It has a high magnitude of environmental pollution and contributes to climate change. This calls for cleaner, reliable, sustainable, decarbonized, decentralized, affordable, digitized with the diversification of energy mix. The study aimed at investigating the impact of dosing selected trace metals (Ni, Co, Cu) as an additive to the substrate in the sludge to energy recovery using anaerobic processes. Sewage sludge and cellulose were used as a substrate. The biomethane potential study was carried from a 500 ml batch automated bio-digester at a mesophilic temperature of 37oC and a substratum-to-inoculum ratio (2:1) of the organic load rate. The dosed micro-nutrients acted as microbial-agents responsible for the anaerobic digestion of the feedstock. Cellulose and sludge at 0.25 mg/L (Ni) recorded the highest production of the biomethane. Cellulose inoculated with cobalt had better biomethane production at 0.02 mg/L until 0.05 mg/L. High production of biomethane was observed at the substrate with a copper concentration of 4.5 mg/L. Adding trace metals to microbial cell surroundings stimulated microbial activity and prevented the accumulation of the fatty acids. However, high concentrations beyond threshold resulted in inhibition, toxicity to the microbial-growth, which was reflected in the reduction of the production of biomethane.
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