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.

Self-cured concrete is a type of concrete with a special ability to reduce autogenous shrinkage responsible for early-stage cracking. It is useful generally for the construction of high rise buildings and bridges. The application and use of this technique of curing concrete, however, depends on the level of awareness among stakeholders regarding the application of the technique and its benefits among other factors. This study, therefore, sets out to investigate the level of awareness of selected construction professionals regarding the self-curing concrete technique in addition to the benefits. A cross-sectional survey design method was embraced by giving out 115 questionnaires to builders and engineers in Lagos who were purposely selected. The data was subjected to descriptive statistics. The results indicate that about 21% of selected builders and civil engineers practicing in Lagos are not aware and familiar with the concept of self-curing technology while about 43.1% of the professionals who have the knowledge of SCT have never used it in their professional practice. In addition, lower permeability, reduced coefficients of thermal expansion, and improved microstructures of cementitious paste were perceived as the dominant benefits of the self-curing concrete method. The implication of this study to construction professionals in Nigeria is in developing capacities on innovation practices in high-strength concrete technologies that will make them strike a balance with international counterparts.

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.

An improved indoor environmental quality (IEQ) is a major determinant of human comfort in an occupied space. The current cross-sectional study investigates the link between indoor environmental quality (IEQ) and sick building syndrome symptoms (SBS) emergence with a case study of selected students’ hostels in a Nigerian private university. A quantitative research design method was adopted where 376 (n = 376) copies of the questionnaire were purposely administered to the student’s occupants. A mini environmental quality meter was also objectively used to measure the indoor air temperature, relative humidity, air velocity, and lighting levels in the selected hostel rooms in February and March 2019. The data obtained were subjected to descriptive and analysis of variance (ANOVA) inferential statistics using the Statistical Package for Social Sciences (SPSS) 25.0 version. The research findings revealed that students show SBS symptoms like tiredness, sensitivity to odor, sneezing, and blocked nose during their hostels’ occupancy. Meanwhile, the objective measurement results showed an average indoor temperature of 29.93 °C, 31.64 °C, and 30.71 °C. Simultaneously, average relative humidity values of 79.00%, 72.06%, and 81.01% were obtained in the monitored rooms for the morning, afternoon, and evening. The ANOVA result established a positive relationship between poor IEQ condition and the SBS symptoms of odor, stuffy nose, and nausea. Therefore, it is recommended that the hostel facilities’ SBS be mitigated through acceptable IEQ parameters of air temperature and relative humidity, increasing students’ wellbeing, academic performance, and reputation.

Secondary aluminum dross (SAD) is a hazardous by-product of the aluminum smelting industry. Among various recycling options of this waste, construction and building materials applications is one of the value-added options to end dumping. The present study, thereby, investigates the influence of SAD on the mechanical and durability properties of sandcrete blocks (SBs). Five partial replacements 0%, 10%, 20%, 30% and 40% of river sand with SAD were experimented at constant water–cement ratio of 0.45. Sixty-three SB samples of size 150 mm × 225 mm × 450 mm were molded and cured at different ages of 7, 14 and 28 days before the hardened blocks were subjected to water absorption and compressive crushing tests. The study results revealed that the water absorption of SAD-blended samples was found to rise with increasing percentage replacement with SAD. Also, the study revealed that beyond 10% replacement with SAD, the investigated properties fall below the required limits as stated in relevant standards. SBs blended with SAD up to 10% of weight of sand could be beneficial for construction economy, healthy living, ecological and sustainable built environment.