Papers

@article{nduka_assessment_2023,

title = {Assessment of Water Transport and Chemical Attack of Meta-Illite Calcined Clay Blended Cement in High-Performance Concrete},

author = {David O. Nduka and Babatunde J. Olawuyi and Blas Cantero-Chaparro and Belén González-Fonteboa},

url = {https://www.mdpi.com/1996-1944/16/22/7149},

doi = {10.3390/ma16227149},

issn = {1996-1944},

year  = {2023},

date = {2023-01-01},

urldate = {2026-08-13},

journal = {Materials},

volume = {16},

number = {22},

pages = {7149},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Rapid urbanisation causes a rise in the need for infrastructure, which in turn fuels the creation of additional concrete and further increases cement supplies. Activation of illite-based clay mineral and usage in concrete production is one of the sustainable ways to address the cement industry anthropogenic issues. This study evaluates the durability properties of water transport (water absorption, and capillary water absorption), and resistance to aggressive environments (5% solutions of hydrochloric acid, HCl; sodium sulphate, Na2SO4; and calcium chloride, CaCl2) of meta-illite calcined clay (MCC)-based high-performance concrete (HPC). For this purpose, concrete was produced with 5, 10, 15, 20, 25 and 30% MCC content in partial substitution of CEM II. Results from the water absorption tests indicate an average percentage value of 3.57%, 3.35% and 2.52% for all the observed mixes at 28, 56 and 90 days, respectively, with MCCC-10 HPC having an average best value of 2.23% across the curing ages. On all observed days, the 5 to 15% cement replacements had very close average water sorptivity value of 0.125 ± 0.001 mm/min0.5 with the control mix (0.113 ± 0.011 mm/min0.5). The aggressive environments exposure findings of the hardened MCC-based HPC specimens of 10 to 20% recorded an approximately 15% compressive strength loss in HCl, Na2SO4 and CaCl2 solutions over the 90 days of curing. In all, the HPC mixes of 5 to 15% MCC content obtained an average durability performance factor of 89%. As a result, these findings imply that MCC can replace cement in up to 15% of HPC production.},

keywords = {durability properties, high-performance concrete, meta-illite calcined clay, superabsorbent polymers},

pubstate = {published},

tppubtype = {article}

}

@article{nduka_mechanical_2022,

title = {Mechanical and microstructural properties of high-performance concrete made with rice husk ash internally cured with superabsorbent polymers},

author = {David O. Nduka and Babatunde J. Olawuyi and Emmanuel O. Fagbenle and Belén González-Fonteboa},

url = {https://www.sciencedirect.com/science/article/pii/S240584402201790X},

doi = {10.1016/j.heliyon.2022.e10502},

issn = {2405-8440},

year  = {2022},

date = {2022-09-01},

urldate = {2026-08-10},

journal = {Heliyon},

volume = {8},

number = {9},

pages = {e10502},

abstract = {An experimental study was carried out to determine the properties of rice husk ash (RHA) and its effect on high-performance concrete's (HPC) mechanical and microstructural properties. RHA content was placed at 0–30% at 5% step intervals and a constant water-binder ratio (W/B) of 0.3. A slump flow test was carried out to measure the workability property of the fresh HPC. In contrast, the influence of RHA contents on compressive, splitting tensile, flexural strengths and microstructural properties were examined for the hardened HPC specimens. The X-ray fluorescence (XRF), scanning electron microscopy-energy dispersive x-ray (SEM-EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy-Attenuate total reflectance (FTIR-ATR), Thermogravimetry analysis (TGA), Brunauer, Emmett and Teller (BET) specific surface area and laser diffraction particle size distribution (PSD) were used to access the feasibility of RHA in HPC. XRD and SEM/EDX techniques were conducted to investigate the hydration products and microstructure in hardened HPCs. The post-test examination showed increased compressive, splitting tensile and flexural strengths of HPC samples for a 10% RHA content mix, recording the highest compressive strength in all curing ages. As the curing ages increase, the microstructure of the samples with RHA becomes denser than the control due to the refinement of the microstructure by the RHA incorporated. The XRD and SEM/EDX confirmed the lower calcium hydroxides from pozzolanic reactivity and later formation of C–S–H. The results suggest that RHA can be used as a cement replacement for up to 10% in HPC to produce sustainable concrete.},

keywords = {high-performance concrete, Internal curing, Microstructure and mechanical properties, Rice husk ash, superabsorbent polymers},

pubstate = {published},

tppubtype = {article}

}

@article{nduka_assessment_2022,

title = {Assessment of the Durability Dynamics of High-Performance Concrete Blended with a Fibrous Rice Husk Ash},

author = {David O. Nduka and Babatunde J. Olawuyi and Olabosipo I. Fagbenle and Belén González-Fonteboa},

url = {https://www.mdpi.com/2073-4352/12/1/75},

doi = {10.3390/cryst12010075},

issn = {2073-4352},

year  = {2022},

date = {2022-01-01},

urldate = {2026-08-10},

journal = {Crystals},

volume = {12},

number = {1},

pages = {75},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {The present study examines the durability properties of Class 1 (50–75 MPa) high-performance concrete (HPC) blended with rice husk ash (RHA) as a partial replacement of CEM II B-L, 42.5 N. Six HPC mixes were prepared with RHA and used as 5%, 10%, 15%, 20%, 25%, and 30% of CEM II alone and properties are compared with control mix having only CEM II. The binders (CEM II and RHA) were investigated for particle size distribution (PSD), specific surface area (SSA), oxide compositions, mineralogical phases, morphology, and functional groups using advanced techniques of laser PSD, Brunauer–Emmett–Teller (BET), X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared/attenuated total reflection (FTIR/ATR), respectively, to understand their import on HPC. Durability properties, including water absorption, sorptivity, and chemical attack of the HPC samples, were investigated to realise the effect of RHA on the HPC matrix. The findings revealed that the durability properties of RHA-based HPCs exhibited an acceptable range of values consistent with relevant standards. The findings established that self-produced RHA would be beneficial as a cement replacement in HPC. As the RHA is a cost-effective agro-waste, a scalable product of RHA would be a resource for sustainable technology.},

keywords = {durability properties, high-performance concrete, Rice husk ash, superabsorbent polymers, Sustainability},

pubstate = {published},

tppubtype = {article}

}

@article{nduka_effect_2021,

title = {Effect of KyAl4(Si8-y) O20(OH)4 Calcined Based-Clay on the Microstructure and Mechanical Performances of High-Performance Concrete},

author = {David O. Nduka and Babatunde J. Olawuyi and Olabosipo I. Fagbenle and Belén González-Fonteboa},

url = {https://www.mdpi.com/2073-4352/11/10/1152},

doi = {10.3390/cryst11101152},

issn = {2073-4352},

year  = {2021},

date = {2021-10-01},

urldate = {2026-08-06},

journal = {Crystals},

volume = {11},

number = {10},

pages = {1152},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {The work described in this paper has been performed to determine the potential use of meta-illite (KyAl4(Si8-y) O20(OH)4) calcined clay (MCC) as a supplementary cementitious material (SCM) in a binary Portland cement (PC) for high-performance concrete (HPC) production. 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 and mechanical properties (compressive, splitting tensile and flexural strengths) and microstructure (morphology and crystalline phases) of hardened MCC-based HPCs were determined. The XRF result shows that the 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 majorly an illite-based clay mineral calcined at a maximum temperature of 650 °C, as revealed by the TGA. The MCC addition increases the slump flow of HPCs at 5–15% cement replacement. The MCC incorporation at 10% cement replacement best improved the porosity of HPCs at a later age resulting in increased mechanical and microstructural properties of tested samples. Therefore, it is recommended that MCC addition within 10% cement replacement be adopted for low W/B Class I HPC at no deleterious results on mechanical and microstructural properties of the concrete.},

keywords = {dehydroxylation, high-performance concrete, meta-illite calcined clay, superabsorbent polymers, superplaticiser, Supplementary cementitious materials},

pubstate = {published},

tppubtype = {article}

}