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Affordable housing issue : experimental investigation on properties of eco-friendly lightweight concrete produced from incorporating periwinkle and palm kernel shells

Effect of a Synthetically Modified Natural Zeolite Additive on Properties and Durability of Cement Mortars

Effect of mix parameters on strength of geopolymer mortars - experimental study

  • Authors: Naghizadeh, A. , Ekolu, S. O.
  • Date: 2018
  • Subjects: Fly ash , Geopolymer , Compressive strength
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/279861 , uj:30062 , Citation: Naghizadeh, A. & Ekolu, S.O. 2018. Effect of mix parameters on strength of geopolymer mortars - experimental study.
  • Description: Abstract: In this article, an investigation is reported on development of strength in South African fly ash (FA) – based geopolymer mixtures. Locally available Class F, FA from one of the coal power stations was used in the investigation. The alkali-activator used consisted of sodium silicate (SS) and sodium hydroxide (SH) mixed in varied ratios of 1.0, 1.5, 2.0, 2.5 and 3.0 SS to SH. The SS of silicate modulus = 2.5 was used but the SH concentration in the activator was varied to 10, 12, 14M NaOH. Mortars of 2.25 aggregate/binder ratio were used to prepare 50 mm cubes. In preparing mortar mixtures, the liquid to solids (L/S) ratios were varied to L/S = 0.3, 0.4, 0.5 and 0.6. Mortar cubes were cast and cured at 80oC for 7 days then tested for compressive strength. It was found that all three parameters consisting of SS/SH ratio of the activator, concentration of NaOH used in the activator and the L/S ratio, showed significant influence upon compressive strength development. The optimum strength of the geopolymer mortar mixtures was obtained at SS/SH = 2.0, 12M NaOH concentration ad L/S = 0.5.
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Indicative tests on the effect of fly ash - β cyclodextrin composite on concrete workability and strength.

  • Authors: Ikotun, Bolanle D. , Fanourakis, George C. , Mishra, Shivani
  • Date: 2014
  • Subjects: β cyclodextrin , Compressive strength , Fly ash , Split tensile strength
  • Type: Article
  • Identifier: uj:4934 , http://hdl.handle.net/10210/13034
  • Description: Fly ash – βcyclodextrin interaction has shown to have formed a composite that might be useful in concrete technology [1]. Since the effect of this composite on concrete properties has not been documented in an open literature, there is a need to run indicative tests that will give guidance for on-going research. This paper presents the results of the indicative tests on the effect of fly ash-β cyclodextrincomposite on concrete workability and strength (compression and split tensile). All the mixtures included 30 % fly ash (FA) by mass. The βcyclodextrin (β-CD) was mixed with the FA, in separate mixtures, in proportions of 0.1 %, 0.2 % and 0.5 %. Two sample preparation procedures were followed for FA-β-CD composites mixtures; firstly, physical mixtures of a pre-weighed amount of β-CD and FA were adopted for the dry mixtures and secondly, 0.0103M, 0.0206M and 0.0516Mβ-CD solutions were added to the concrete at the mixing stage for solution mixtures.The results obtained showed that an increased content (0.5%) of β-CD in concrete both for dry and solution mixtures had a detrimental effect on both workability and strength. However, lower percentages (0.1% and 0.2%) of β-CD improved both workability and the strength of the concrete.
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Properties of mortars made with waste glass as fine aggregate – a South African study

  • Authors: Mokoni, Palesa P , Ekolu, Stephen O , Quainoo, Harry
  • Date: 2019
  • Subjects: Waste glass , Compressive strength , Expansion
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/407014 , uj:34243 , Citation: Mokoni, P.P., Ekolu, S.O., Quainoo, H. 2019 : Properties of mortars made with waste glass as fine aggregate – a South African study.
  • Description: Abstract : An investigation was conducted on the potential use of waste glass (WG) as fine aggregates in mortars. It is estimated that 7.2 % of the waste stream in South Africa consists of glass. Much of this WG is disposed to landfills. In the present study, mortar mixtures of 3.0 aggregate/cement ratio and water/cement ratio of 0.6 were used. WG was incorporated as partial replacement of granite fine aggregate in proportions of 0, 20, 30, 50 and 70%WG. Mortar cubes of 50 mm size and prisms of size 25 x 25 x 285 mm, were prepared. The tests conducted include density and workability, compressive strength and expansion due to alkali-silica reaction (ASR) as per ASTM C 1260. It was found that workability increased with increase in the proportion of WG incorporated into the mixtures, while density and compressive strength correspondingly decreased. Strength loss not exceeding 11% was obtained for proportions of 20 to 30% WG fine aggregate. Also, 20% WG mixture gave ASR expansion of less than 0.10% at 16 days which satisfies the requirement for non-expansive cementitious systems.
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Properties of pervious concrete for hydrologic applications

  • Authors: Ekolu, Stephen O. , Diop, Souleymane , Azene, Firehiwot
  • Date: 2016
  • Subjects: Pervious concrete , Compressive strength , Porosity
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/214004 , uj:21224 , Citation: Ekolu, S.O., Diop, S & Azene, F. 2016. Properties of pervious concrete for hydrologic applications.
  • Description: Abstract: This paper presents an experimental investigation that was conducted to examine those properties of interest with regard to the passage of water through pervious concrete. A total of 30 mixtures of pervious concrete were prepared at water-cementitious ratios (w/cm) varied from 0.25 to 0.40. Three aggregate types and sizes were used consisting of 13.2, 9.5 and 6.7 mm granite stone; 6.7 mm shale and 9.5 mm dolomite. Pozzolans were incorporated into mixtures in proportions of 20, 30 and 50% fly ash (FA) or 30% and 50% ground granulated blast furnace slag (GGBS). Compressive strength development in the mixtures was monitored at 7, 14, and 60 days. It was found that strength gain after 14 days generally occurred only in mixtures containing pozzolans. A unique behavior in property relations of pervious concrete was found with compressive strength increasing and porosity decreasing with increase in w/cm, contrary to established knowledge of conventional concrete properties. It was found that mixtures made with 6.7 or 9.5 mm granite stone gave porosity and permeability characteristics that were most suitable for hydrologic applications. Similarly, incorporation of 20% FA, 30% or 50% GGBS in the mixtures gave the most appropriate mechanical and transport properties.
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Strength and durability effect of modified zeolite additive on concrete properties

  • Authors: Ikotun B.D , Ekolu S
  • Date: 2010
  • Subjects: Modified zeolite additive , Compressive strength , Fly ash
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/62121 , uj:16889 , Ikotun B. and Ekolu, S., 2010, Strength and durability effect of modified zeolite additive on concrete properties, Construction and Building Materials, 24 (2010) 749-757.
  • Description: Abstract:This paper presents an investigation into the effect of a modified zeolite additive (PWC) on strength and durability behaviour of concrete. The additive, a blend of selected alkaloids and zeolite, is commercially available and effectively used in soil stabilization for road construction. However, its influence on behaviour and performance for use in concrete has not been explored. In this research, concrete samples were prepared by incorporating PWC and/or 30% fly ash in the mixes. PWC was used in proportions of 0.6 %, 0.8%, and 1.0 % of the weight of cement. Concretes or mortars of 0.5 water/cementitious ratio were subjected to split tensile strength, compressive strength, oxygen permeability, sorptivity, and porosity tests. Hydration behaviour of the cementitious systems and the pozzolanic effect of PWC additive were studied using differential thermal analysis and thermogravimetric analysis. Results show that PWC is effective in improving concrete strength when used at optimum proportions found to be between 0.6 % and 1.0 %. Sorptivity property of concrete was improved with use of PWC regardless of its proportion in the mix, while permeability of concrete improved only in the presence of 30 % fly ash.
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Studies of Ugandan Volcanic Ash and Tuff

The effect of fly ash, β-cyclodextrin and fly ash-β-cyclodextrin composites on concrete workability and strength

  • Authors: Ikotun, B. D. , Fanourakis, George C. , Mishra, Bhardwaj S.
  • Date: 2017
  • Subjects: Composite , Compressive strength , Cyclodextrin
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/241655 , uj:24908 , Citation: Ikotun, B.D., Fanourakis, G.C. & Mishra, B.S. 2017. The effect of fly ash, β-cyclodextrin and fly ash-β-cyclodextrin composites on concrete workability and strength.
  • Description: Abstract: To increase the use of fly ash (FA) as a pozzolanic material in concrete, a composite was formed with an interaction of FA with β-cyclodextrin (β-CD). Further research was carried out in this article to study the effects of replacing cement with FA (30% and 50% by mass), β-CD (0.025%, 0.05% and 0.1%) and FA-β-CD composite on the workability and strength of concrete. Workability was assessed by means of the slump test and strengths were assessed using the compressive and split tensile strength tests. Higher combined contents of FA and β- CD resulted in increased workability of concrete of up to approximately 550 %. Furthermore, the inclusion of β-CD generally increased both the compressive and tensile strengths of the concretes not containing FA by up to 10 %. When combined with FA, the β-CD resulted in increased compressive strengths of up to 63 % and tensile strengths of up to 28 %, compared to the relevant pozzolanic concretes which did not include β-CD. The study contributed to the knowledge of FA performance using cyclodextrin and promoted the continued inclusion of FA in concrete, which in turn should reduce the environmental pollution resulting from FA.
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Thermal behaviour of high volume fly ash concrete and its temperature simulation

  • Authors: Gaunt, Peter G. , Versfeld, Mathew K.R. , Ferreira, André , Ekolu, Stephen O.
  • Date: 2017
  • Subjects: High volume fly ash concrete , Compressive strength , Durability
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/248106 , uj:25783 , Citation: Gaunt, P.G. 2017. Thermal behaviour of high volume fly ash concrete and its temperature simulation.
  • Description: Abstract: In this paper, it is shown that Class F fly ash (FA) can be effectively used in high volumes as a supplementary cementitious material (SCM). High volume use of FA is of interest in promoting the development and application of green materials. In South Africa, there is little or no literature on high volume incorporation of locally available FA in concrete. In this investigation, six different concrete mixes of water/cementitious ratios (w/cm’s) = 0.3 and 0.45, were used. The mixtures consisted of 0, 30, 50 and 70% FA. Tests carried out were workability, bleeding, compressive strength and heat of hydration. Large 300 mm cubes were 2 used to study hydration heat development in fresh concrete. As expected, concrete strength decreased as FA content increased owing to the slower rate of strength development in FA mixtures. It was found that heat of hydration generated in HVFA mixes gave lower peak temperatures compared to mixes without FA, producing reductions of 27% to 43.5% in peak temperatures for mixtures containing 50% and 70% FA respectively. Temperature simulation using ConcreteWorks gave predictions correctly depicting the measured temperature profiles but with slight under-estimation of peak temperatures.
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