DEVELOPMENT OF HIGH-PERFORMANCE CONCRETE FROM METASTABLE CALCINED CLAY AND RICE HUSK ASH WITH SUPERABSORBENT POLYMERS

Nduka, David (2022) DEVELOPMENT OF HIGH-PERFORMANCE CONCRETE FROM METASTABLE CALCINED CLAY AND RICE HUSK ASH WITH SUPERABSORBENT POLYMERS. Masters thesis, Covenant University Ota..

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Abstract

The research was conducted to determine the potential use of metastable calcined clay (MCC) as a supplementary cementitious material (SCM) in a binary binder for high-performance concrete (HPC) production. The attractive properties of calcined clay based on literature have influenced an SCM choice in concrete production. Therefore, to improve the performance of the structural elements regarding increasing height, span length, and load, a thermally activated MCC of Nigerian origin gave a point of view to more investigation and compared with rice husk ash (RHA). Different HPC mixtures at 5-30% with MCC or RHA content of cement replacements of five steps intervals were produced with superabsorbent polymers (SAP) introduced as an internal curing agent. The water-binder ratio (W/B) of all the mixes was kept constant at 0.3 while Masterglenium Sky 504, a polycarboxylate ether-based superplasticiser (PCE), was used to improve the HPCs workability. To obtain the properties of the cementitious materials, the chemical composition, mineral phases, morphology, calcination efficiency, and physical properties were quantitatively analysed using the advanced techniques of X-ray fluorescence (XRF), scanning electron microscopy/energy dispersive x-ray (SEM/EDX), X-ray diffraction (XRD), Fourier transform infrared/Attenuated total reflection (FTIR/ATR), Thermogravimetric analysis (TGA), laser particle sizing and Brunauer–Emmett–Teller (BET) nitrogen absorption method. The MCC's effect on the workability, early-age degree of hydration, early-age compressive strength, hardened mechanical properties (compressive, splitting tensile and flexural strengths), durability (water absorption, sorptivity, and chemical attack), and microstructure (morphology and crystalline phases) of hardened MCC based HPCs samples were determined. The determined early-age compressive strength of HPC mortar was further curve-fitted into Powers' model to assess the relationship between compressive strength and gel/space ratio. All the properties of HPCs containing MCC were compared to those of PC mixes. The XRF result shows that the chemical oxide composition of MCC confirmed the pozzolanic material requirements with recorded high useful oxides content. At the same time, the SEM image presents particles of broad, solid masses with a wider surface area of irregular shape. The XRD results show that the MCC was a major illite-based clay mineral calcined at a maximum temperature of 650 ℃, as revealed by the TGA. The MCC addition increases the slump flow of HPCs at certain cement replacement with a comparative early-age compressive strength with the control. The MCC incorporation at 10% cement replacement best improved the porosity of HPCs at a later age resulting in increased mechanical, durability, and microstructural properties of tested samples. A simulation of MCC and RHA contents into the Powers' model signalled compatibility for predicting strength development trends in the HPC with SAP. The study has shown that MCC and RHA, which are locally sourced, can be used to produce Class I (50 – 75 MPa) HPC with enhanced mechanical, durability and microstructural properties. Therefore, it is recommended that MCC addition within 10% binder content be adopted for low W/B Class I HPC at no deleterious results on mechanical and microstructural properties of the concrete.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	High-performance concrete, metastable calcined clay, rice husk ash, superabsorbent polymers, supplementary cementitious materials, Sustainable Development Goals 9,12 and 13
Subjects:	T Technology > TD Environmental technology. Sanitary engineering T Technology > TH Building construction
Divisions:	Faculty of Engineering, Science and Mathematics > School of Civil Engineering and the Environment
Depositing User:	Mrs Patricia Nwokealisi
Date Deposited:	28 Mar 2022 12:30
Last Modified:	28 Mar 2022 12:30
URI:	http://eprints.covenantuniversity.edu.ng/id/eprint/15764

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