Assessment of activity moduli and acidic resistance of slag-based geopolymer concrete incorporating pozzolan

The environmental impact of Portland cement production and utilization in the construction sector has led to the global call for the use of eco-friendly construction materials for the production of cleaner and sustainable products. Therefore, this study explored agro-industrial wastes, slag and corncob ash, for the production of geopolymer concrete (GPC). Corncob was dehydroxylated at 600 �C for 3 h and partially used as a replacement for slag at 0%, 20 %, 40 %, 60 %, 80 %, and 100 %. A 12 M, 14 M, and 16 M of both sodium silicate (SS) and sodium hydroxide (SH) were used as activators. The chemical moduli of each and mixed binder were quantified and evaluated based on the major reactive oxides, hence leading to the evaluation of reactivity indexes (RIs). Moreover, the RIs and mix design properties (MDPs) of concrete were used for the prediction of flexural strength while the chemical resistance of each concrete sample was investigated. Compared with the experimental results, the predictive flexural strengths based on the RIs and the MDPs yielded a high precision with R2 ranging from 88–92 % at 7–90 days, respectively. Moreover, the GPC, unlike Portland cement concrete (PCC), resisted the more acidic attack. Therefore, the use of GGBFS�CCA blended concrete would be more advantageous in a highly acidic environment than PCC. Ultimately, the models proposed by this study can be useful in the concrete mix design procedure for the flexural strength development of GPC incorporating agro-industrial provided the oxide compositions of each and mixed material were obtained

Awareness, benefits and drawbacks of net zero energy building practices: construction industry professional’s perceptions

In a bid to overcome climate change and global warming, the adoption of net zero energy building (nZEB) practices in construction projects has become a viable measure of reducing energy consumption and CO2 emissions in buildings. nZEB is a facility with a significantly lowered energy needs such that the rest of the energy requirements can be supplied by on-site or off-site renewable technologies. The present study therefore investigated the awareness, benefits and challenges confronting the actualization of nZEB in Nigeria construction industry. A cross sectional survey design was adopted wherein a close ended questionnaire was purposively administered online to construction industry professionals who have understanding of nZEB initiatives. Descriptive statistical tests were conducted, with the results showing about 9% and 25% of the selected professionals been not aware of nZEB concepts and have not been involved in the concept in their professional career. Further details revealed that reduction in the land use effect, reduction in vulnerability of power infrastructures to vandalism and economic competitiveness were dominant benefits of nZEB practices. However, low return on investment, conflict with public policy regulation and policy clarity, lack of evaluation and valuation processes were perceived as the top hindering factors to nZEB practices. The implication for practice is for construction stakeholders to participate and develop effective implementation strategies towards nZEB for could be ecological and economical friendly

Mining for viral fragments in methylation enriched sequencing data

Most next generation sequencing experiments generate more data than is required for the experimental set up. For example, methyl-CpG binding domain (MBD) affinity purification based sequencing is often used for DNA-methylation profiling, but up to 30% of the sequenced fragments cannot be mapped uniquely to the reference genome. Here we present and evaluate a methodology for the identification of viruses in these otherwise unused paired-end MBD-seq data. Viral detection is accomplished by mapping non-reference alignable reads to a comprehensive set of viral genomes. As viruses play an important role in epigenetics and cancer development, 92 (pre)malignant and benign samples, originating from two different collections of cervical samples and related cell lines, were used in this study. These samples include primary carcinomas (n=22), low- & high-grade cervical intrapeithelial neoplasia (CIN1 & CIN2/3 - n=2/n=30) and normal tissue (n=20), as well as control samples (n=17). Viruses that were detected include phages, adenoviruses, herpesviridae and HPV. HPV, which causes virtually all cervical cancers, was identified in 95% of the carcinomas, 100% of the CIN2/3 samples, both CIN1 samples and in 55% of the normal samples. Comparing the amount of mapped fragments on HPV for each HPV-infected sample yielded a significant difference between normal samples and carcinomas or CIN2/3 samples (adjusted p-values resp. < 10^-5, < 10^-5), reflecting different viral loads and/or methylation degrees in non-normal samples. Fragments originating from different HPV types could be distinguished and were independently validated by PCR-based assays with a specificity of 98% and a sensitivitity of 66%. In conclusion, although limited by the a priori knowledge of viral reference genome sequences, the proposed methodology can provide a first but substantial insight into the presence, concentration and types of methylated viral sequences in MBD-seq data without additional costs

Appraisal of Municipal Solid Waste Management, Its Effect and Resource Potential in A Semi-Urban City: a Case Study

Managing municipal solid wastes (MSW) is progressively becoming a major challenge in many cities of developing nations because of rapid urbanization and rise in population. This can be described by ineffective collection methods, inadequate coverage of the collection, processing system and inappropriate disposal. This paper presents the current state of solid waste management in a semi-urban city, its associated challenges and prospects that are within. A field work that involves the characterization and types of the waste generated, and frequency of collection was carried out within the study area. Four locations where the major waste bins are located within the city were considered. A representative sample of 280 kg was used for the waste characterization, and the results show that about 64% of the wastes are recyclable with lots of organic waste that can be used as compost. The only dump site in the city was visited in order to obtain useful information concerning the present state of solid waste management. The study revealed that there is presently no investment made to the existing development plan to introduce a modern waste management system. The study suggests new approach that could be used by institutions and government agencies for MSW management to realize a sustainable and efficient sanitation, and possible resources generation potentials that could be harnessed from the waste stream

Effect of Substitution of Crushed Waste Glass as Partial Replacement for Natural Fine and Coarse Aggregate in Concrete.

Reusing of waste glass in concrete production is among the attractive option of achieving waste reduction and preserving the natural resources from further depletion thereby protecting the environment and achieving sustainability. This present study examines the possible reuse of waste glass crushed into fine and coarse aggregate sizes as partial substitute for natural fine and coarse aggregate in concrete. The variables in this study is both the fine and coarse aggregate while the cement and water-cement ratio were held constant. The crushed glass was varied from 0 – 100% in steps of 25% by weight to replace the both the natural fine and coarse aggregate in the same concrete mix. Concrete mixes were prepared using a mix proportion of 1:2:4 (cement: fine aggregate: coarse aggregate) at water-cement ratio of 0.5 targeting a design strength of 20 MPa. Tests were carried out on total number of 90 concrete cube specimens of size 150 x 150 x150 mm and 90 concrete cylinder specimens of dimension 100 mm diameter by 200 mm height after 3, 7, 14, 28, 42 and 90 days of curing. Test results indicated that the compressive and split tensile strength of the hardened concrete decreases with increasing waste glass content compared with the control. However, concrete mix made with 25% waste glass content compared significantly well with the control and can be suitably adopted for production of light weight concrete

An exploration of the collaborative processes of making theatre inspired by science

This research examined the collaborative processes of making theatre inspired by science through the analysis of 16 semi-structured interviews with individual collaborators (eight theatre practitioners and eight scientists). Interviews explored experiences, including their motivations, working processes, challenges, learning and understanding. Roles of scientists in the collaboration ranged from expert advisor to equal creative collaborator. Factors affecting partnerships included curiosity for each other's practice, social interaction and mutual respect. The research suggests that scientists could be motivated to undertake 'Sci-Art' collaborations through personal interest, as well as previously identified motives such as encouragement from their department. The project also identified benefits to researchers from such collaborations, including developing new perspectives on their own practice. © The Author(s) 2011

Geopolymer concrete incorporating agro-industrial wastes: Effects on mechanical properties, microstructural behaviour and mineralogical phases

The increasing effects of environmental degradation and global warming owing to the production of Portland cement for uses in the construction industry premise the need for sustainable construction materials. This study, therefore, harnessed corncob ash (CCA) and ground granulated blast furnace slag (GGBFS) for the production of geopolymer concrete (GPC) at ambient curing conditions. Corncob was dehydroxylated at 600 °C and partially used as replacement for GGBFS at 0%, 20%, 40%, 60%, 80%, and 100%. The activators used were sodium silicate (SS) and sodium hydroxide (SH), while the molar concentrations of SH were varied at 12 M, 14 M, and 16 M. Moreover, mechanical properties, microstructural behaviour and mineralogical phases of the selected samples were examined. The results revealed that up to 40% CCA replacement level exhibited higher strengths than Portland cement concrete (PCC). Besides, a good relationship exists between the experimental results and the proposed model equations. These proposed models can be beneficial in the development of the strength design of GPC and PCC incorporating agro-industrial wastes. Furthermore, the study shows the possibility of incorporating CCA with GGBFS for production of GPC and the tenability of curing GPC at ambient conditions for the structural application was also attained

The Study of Periwinkle Shells as Fine and Coarse Aggregate in Concrete Works

For a country like Nigeria and indeed the third world countries at large, to be able to achieve a sustainable infrastructural development particularly in the area of housing in the nearest future, low cost building materials especially those readily available within each geo political areas must be exploited and used to make housing affordable for all and sundry. The inflationary trend in the Nigeria economy escalated the cost of building materials to the extent that many of the conventional building materials are no longer affordable for the construction of low cost housing. This research presents the study of the suitability of periwinkle shells as fine and coarse aggregate in construction works. Experimental and statistical approach was adopted in this project. Physical and mechanical properties of periwinkle shells and crushed granite were determined and compared. A total of sixty (60) concrete cubes of size 150 x 150 x 150 mm with different percentages by weight of crushed granite to periwinkle shells as fine and coarse aggregate in order of 0%, 10%, 30%, 50% and 100% inclusion of periwinkle shells were cast, tested and their physical and mechanical properties were determined. Compressive strength test showed that 30% replacement of granite by periwinkle shells and 30% replacement of sharp sand by periwinkle fine aggregate were satisfactory without compromise in compressive strength requirement for a mix ratio 1:2:4. Also, the cost analysis shows a 24% savings in cost when periwinkle shells are used holistically (100%) as coarse aggregate and 6.8% savings in cost when 30% are used to replace granite as coarse aggregate

Mechanical properties of high strength eco-concrete containing crushed waste clay brick aggregates as replacement for sand

Utilization of clay brick wastes for production of high strength eco-concrete enables the combat of raw resources depletion due to excessive mining as well as mitigating environmental pollution caused by demolition of old brick structures in an effort to achieve environmental sustainability in line with the sustainable development goals (SDGs). This study investigates the beneficial usage of crushed clay brick as partial replacement for natural sand in producing high strength eco-friendly concrete. The replacement percentages of the crushed clay brick in respect to sand are 0, 10, 20, 30, 40 and 50% by weight using a mix proportion ratio of 1:1:2 at a constant water-cement ratio of 0.25, aiming at the 28 days compressive strength of about 40 MPa. The chemical characterization of the crushed clay brick and cement was conducted via X-ray fluorescence (XRF). The mechanical properties tests were performed on about 80 specimens using 100 x 100 x 100 mm for cubes, 100 x 100 x 500 mm for beams and 100 x 200 mm diameter for cylinders after 7, 14 and 28 days of curing in water. Results showed that concrete containing crushed clay brick as partial replacement for sand compare favourably well with the control. Consequently, it is suggested that generated clay brick wastes can be crushed and used as replacement for natural sand for the production of eco-friendly high strength concrete

Decades of water resources research works in Nigeria: What has changed?

Several studies have been conducted to understand the quantity and quality of water resources in Nigeria. These studies, spanning several decades, conducted in different locations in Nigeria looked at various potable water sources and the effects of anthropogenic activities on the water quality. Despite the findings of these research works, millions of people in Nigeria still lack access to clean water. Reflecting on this has resulted in many questions. What have we learned from the previous studies related to the provision of potable water in Nigeria and how has that influenced our current understanding, policies, decisions and use of available water sources? Has there been any change and what is the hope for securing adequate potable water sources? What steps are being taken to ensure equal distribution of good quality water? We examined the findings of some previous studies: Sustainable groundwater exploitation in Nigeria (2013), Nigeria’s legal instruments for land and water use: implications for national development (2015); Public feedback on state of domestic water supply in Lagos: implications for public health (2016); A wake up call: Nigeria water supply, sanitation, and hygiene poverty diagnostic (2017) and Water, Sanitation and Hygiene: National Outcome Routine Mapping (WASH NORM, 2019). Scrutinizing these five previous studies and other recent ongoing studies will bring to fore how far Nigeria has gone towards achieving the United Nations’ sustainable development goal of clean water by 2030