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

The use of recycled concrete aggregate for concrete production incorporating calcined clay as pozzolanic admixture

Concrete is the most widely used construction material thereby required a lot of raw resources to keep up with its demand. This leads to depletion of raw resources as well as a continuous build-up of demolished concrete wastes (DCW). In most developing nations like Nigeria, the usual way of disposing these DCW is landfilling. However, recycling has become a viable options for conserving the raw resources and reducing greenhouse gases. This study examines the alternative way of reusing concrete wastes for production of fresh structural concrete. The DCW was obtained from the demolition of an existing concrete building and were treated by soaking in water to help reduce the amount of adhered mortar. A mix ratio of 1:1:2 was adopted with a water-cement ratio of 0.25 to attain a relatively high strength concrete and superplasticizer was added to ensure workable mixes. The recycled aggregates (RCA) were used as partial and complete substitute for natural coarse aggregates in percentages of 0, 20, 40, 60, 80 and 100%, while calcined clay was added as pozzolanic admixture into the mixes at 15% and 20% partial replacement for cement. Tests carried out include the physical characterization of the constituent materials and the compressive strength of the hardened concretes were determined after 7, 14 and 28 days of curing in water using cubes of 100 mm × 100 mm × 100 mm. Results showed that the recycled concrete aggregates has high water absorption due to its porous interface. Moreso, results clearly indicate a continual decreasing trend in the compressive strength as the percentages of the RCA increases, however, a significant increase in compressive strength was observed when calcined clay was added as substitute for cement thereby improving the strength development of concrete

Workability, strength, and microstructure of high strength sustainable concrete incorporating recycled clay brick aggregate and calcined clay

This study examines the workability, strength, and microstructure of high strength eco-concrete incorporating recycled clay brick aggregate and calcined clay. The study adopted a design mixes proportioning of 1:1:2 by weight at a constant water/binder ratio of 0.25. The waste bricks were crushed, then used to partially substitute sand at levels of 0, 10, 20, 30, 40, and 50%, while calcined clay was used as a pozzolanic supplement was blended with cement at a constant replacement dosage of 10%. The workability was determined using the slump apparatus. The compressive, split tensile and flexural strengths of the hardened samples were evaluated using cubes, cylinders and beams of dimension 100 mm3, 100 x 200 mm and 100 x 100 x 550 mm, respectively. Scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDX) was conducted on selected samples. Results from the tests indicated a decreasing trend in the workability as the recycled clay brick content increases. Results on the mechanical properties show some levels of improvement in the strength performance and microstructure of the hardened samples containing recycled clay brick aggregate, not beyond 30% at constant calcined clay content. Concrete mix with 10% recycled clay brick aggregate and 10% calcined clay achieved a higher strength compared to the control. This implies that recycled clay brick aggregate can be utilize in the production of structural concrete

Effect of Biochar on Macronutrients Release and Plant Growth on Degraded Soil of Lafia, Nasarawa State, Nigeria

This study consisted of laboratory incubation and pot experimentation. Laboratory incubation was conducted at the Chemistry Laboratory, College of Agriculture, Lafia. The pot experimentation was done in the screen house of faculty of Agriculture, Nasarawa State University Lafia campus during the dry season of 2015 to assess weekly macronutrients (NPK) release in soil amended with locally produced sawdust and rice husk biochar and the growth and nutrient uptake of maize grown on the same soil. The experimental design used was complete randomized design (CRD) and the treatments consisted of three levels of rice and sawdust biochar: 0, 60, 120 g factorially combined to form 9 treatments. The result showed that, in the first week of incubation, 120 g of rice husk and sawdust biochar produced the highest levels of pH (6.58 and 6.69), Nitrogen (0.56 gkg-1 and 0.48 gkg-1), available phosphorus (27.61 mgkg-1 and 27.73 mgkg-1) and potassium (0.26 cmolkg-1 and 0.23 cmolkg-1) respectively. However, the second week of incubation recorded a reduction in nitrogen (0.39 gkg-1 and 0.44 gkg-1) released with application rates of 120 g of both rice husk and sawdust biochars respectively. There was increased in available phosphorus (35.00 mgkg-1 and 37.20 mgkg-1) and potassium (0.26 cmolkg-1and 0.23 cmolkg-1) and soil pH (6.73 and 6.88) respectively in the second week. In the third week of incubation, there was a continuous decline in soil N (0.35 gkg-1 and 0.36 gkg-1) but, P. K and soil pH consistently showed an increase. Rice husk and sawdust biochar applied at 120 g was significantly (p<0.05)  higher in a number of leaves (7.00 and 8.00); growth height (50.73 cm and 20.67 cm); fresh weight (102.82 g and 26.18 g); dry weight (15.11 g and 2.69 g) respectively. N P and K uptake by maize plants were also significantly (P<0.05) influenced by rice husk biochar application. 120 g of rice husk biochar produced the highest value of maize uptake of N (2.51 gkg-1); P (62.62 mgkg-1) and K (4.28 cmolkg-1). Then, 120 g of saw dust biochar produced maize that took in the highest values of N (3.70 gkg-1); P (59.40 mgkg-1) and K (4.00 cmolkg-1)

Whole genome sequencing reveals a de novo SHANK3 mutation in familial autism spectrum disorder.

Clinical genomics promise to be especially suitable for the study of etiologically heterogeneous conditions such as Autism Spectrum Disorder (ASD). Here we present three siblings with ASD where we evaluated the usefulness of Whole Genome Sequencing (WGS) for the diagnostic approach to ASD.We identified a family segregating ASD in three siblings with an unidentified cause. We performed WGS in the three probands and used a state-of-the-art comprehensive bioinformatic analysis pipeline and prioritized the identified variants located in genes likely to be related to ASD. We validated the finding by Sanger sequencing in the probands and their parents.Three male siblings presented a syndrome characterized by severe intellectual disability, absence of language, autism spectrum symptoms and epilepsy with negative family history for mental retardation, language disorders, ASD or other psychiatric disorders. We found germline mosaicism for a heterozygous deletion of a cytosine in the exon 21 of the SHANK3 gene, resulting in a missense sequence of 5 codons followed by a premature stop codon (NM_033517:c.3259_3259delC, p.Ser1088Profs*6).We reported an infrequent form of familial ASD where WGS proved useful in the clinic. We identified a mutation in SHANK3 that underscores its relevance in Autism Spectrum Disorder

A SHANK3 point mutation in three siblings with Autism Spectrum Disorder.

<p>A) Family pedigree depicting the three probands (III-1, III-2, III-3), parents, their siblings and grandparents. B) Mutation as evidenced by whole genome sequencing compared to reference sequence (GRCh37) at bottom. Broad lines represent aligned reads. The heterozygous deletion is depicted as black, thin lines that interrupt the reads. Each panel depicts the data from one proband, C) Capillary sequencing chromatograms of the probands and their parents. A red arrow signals the position of the deletion. The change in ORF is evidenced by the presence of double peaks after the deletion site caused by heterozygocity. D) Linear representations of the intact <i>SHANK3</i> protein featuring its major domains and the presumptive protein if translated from the mutated sequence. ANK: ankyrin repeats, SH3: SRC Homology 3 domain, PDZ: PDZ domain, Pro: Proline-rich region, SAM: Sterile alpha motif domain.</p