Computational Seismic Analysis of Dry-Stack Block Masonry Wall

In this research the computational modeling of Dry-Stack Block Masonry (DSM) walls subjected to cyclic monotonic loading testing is done. The analytical results were compared with experimental test results of the unreinforced and unconfined DSM cantilever walls subjected to lateral loading along with a constant axial load. ABAQUS has been used for Finite Element Modeling and analysis of the wall. Various material properties are defined for the wall in the software and modeled as a homogeneous material. The proposed numerical models had a good correlation with the experimental data. The test results discussion includes failure moods, load displacement curves, and stress/strain profile. Doi: 10.28991/cej-2021-03091668 Full Text: PD

Impact of Length and Percent Dosage of Recycled Steel Fibers on the Mechanical Properties of Concrete

The global rapid increase in waste tyres accumulation, as well as the looming social and environmental concerns, have become major threats in recent times. The use of Recycled Steel Fiber (RSF) extracted from waste tyres in fiber reinforced concrete can be of great profitable engineering applications however the choice of suitable length and volume fractions of RSF is presently the key challenge that requires research exploration. The present experimental work aims at investigating the influence of varying lengths (7.62 and 10.16 cm) and dosages (1, 1.5, 2, 2.5, 3, 3.5, and 4%) of RSF on the various mechanical properties and durability of concrete. Test results revealed that the varying lengths and dosages of RSF significantly affect the mechanical properties of concrete. The improvements in the compressive strength, splitting tensile strength, and Modulus of Rupture (MOR) of RSF reinforced concrete observed were about 26, 70, and 63%, respectively. Moreover, the RSF reinforced concrete showed an increase of about 20 and 15% in the yield load and ultimate load-carrying capacity, respectively. The durability test results showed a greater loss in compressive strength and modulus of elasticity and a smaller loss in concrete mass of SFRC. Based on the experimental findings of this study, the optimum dosages of RSF as 2.5 and 2% for the lengths 7.62 and 10.16 cm lengths, respectively are recommended for production of structural concrete. Doi: 10.28991/cej-2021-03091750 Full Text: PD

Utilization of Marble Wastes in Clay Bricks: A Step towards Lightweight Energy Efficient Construction Materials

Marble dust is one of the hazardous byproducts of marble-processing factories and requires planned disposal. Its beneficial use as a construction material will add to the sustainability, and most importantly, might overcome the burden of marble waste disposal. However, the use of marble dust in concrete has a negative impact. Therefore, this research examines various properties related to the utilization of such material in ceramic clay, and therefore its effects on the use of clay bricks are investigated. The research activity covers the categorization of marble dust powder from three different sources: Ziarat in Mohmand Agency, Buneer, and Mullagori (Pakistan). Its utilization in different proportions preparation of bricks is also addressed. Through the partial replacement of clay with marble dust from 0 to 30% by weight with amplification of 5%, seven mix designs are examined. The test result includes Bulk density, water absorption, porosity, thermal insulation, and strength. The partial replacement of clay with marble dust reduced its weight, strength and increased its porosity, water absorption, and thermal insulation. Furthermore, the utilization of marble powder in bricks minimizes soil erosion and reduces pollution to the environment. Doi: 10.28991/cej-2021-03091738 Full Text: PD

Experimental Study on the Structural Behavior of Cast in-situ Hollow Core Concrete Slabs

An experimental work has been carried out to study the flexural behavior of cast in-situ hollow core reinforced concrete (HCRC) slabs constructed by using easy, cost effective and implementable techniques in field. The precast elements made of different easily available affordable material i.e. concrete, polyvinyl chloride (PVC) and plaster of paris having voided cross- sections of circular, rectangular and triangular shapes were incorporated in one direction during pouring of concrete with minimum flexural reinforcement to construct HCRC slabs. A total of 14 slab specimens including 02 specimens per specification were tested with third point loading for the assessment of flexural behavior as per ASTM standards C78/C78M. The flexural behavior of HCRC slabs with polyvinyl and plaster of paris elements having hollow cross-sections was comparable with the control solid slabs, however, HCRC slab with concrete pipes showed 7 to 8 percent reduction in flexural strength with 19 to 20 percent reduction in self-weight. All the tested specimens performed well in shear as no shear failure was observed. This study reveals that HCRC slabs with locally available material having hollow cross section elements can be used for the construction of cast in-situ monolithic construction of one-way slabs with ordinary construction techniques. Doi: 10.28991/cej-2020-03091597 Full Text: PD

Numerical Modeling for Engineering Analysis and Designing of Optimum Support Systems for Headrace Tunnel

The empirical and numerical design approaches are considered very important in the viable and efficient design of support systems, stability analysis for tunnel, and underground excavations. In the present research work, the rock mass rating (RMR) and tunneling quality index (Q-system) were used as empirical methods for characterization of rock mass based on real-time geological and site geotechnical data and physical and strength properties of rock samples collected from the alignment of tunnel. The rock mass along the tunnel axis was classified into three geotechnical units (GU-1, GU-2, and GU-3). The support systems for each geotechnical unit were designed. The 2D elastoplastic finite-element method (FEM) was used for the analysis of rock mass behavior, in situ and redistribution stresses, plastic thickness around the tunnel, and performance of the design supports for the selection of optimum support system among RMR and Q supports for each geotechnical unit of tunnel. Based on results, Q support systems were found more effective for GU-1 and GU-2 as compared to RMR support systems and RMR support systems for GU-3 as compared to Q support systems

Synthesis and antimicrobial evaluation of some new 3-alkyl-, 3-(2-naphthyl)isocoumarins and their (dl)-3,4 dihydroderivatives

1322-13273-(Substituted)isocoumarins 3a-c are synthesized by the condensation of homophthalic acid 1 with acid chlorides 2a-c, which on alkaline hydrolysis give keto-acids 4a-c. (dl)-3-(Substituted)-3,4-dihydroisocoumarins 7a-c are obtained by the reduction of keto-acids 4a-c to racemic hydroxy-acids 6a-c followed by cyclodehydration using acetic anhydride. The compounds 3a-c, 4a-c, 5c and 7a-c are assayed for antifungal activity against T. longifusus, C. albicans, A. flavus, M. canis, F. solani and C. glaberata. Structure activity relationship reveals that the antifungal activity of naphthyl substituted isocoumarin is better than that of alkyl substituted isocomarins. Same compounds are also evaluated for in vitro antibacterial activity against different strains of gram-negative and gram-positive bacteria. Antifungal activities of 3c, 5c and 7c are found to be quite higher than the standard drugs against T. longifusus and A. flavus

Seismic performance evaluation of plastered cellular lightweight concrete (CLC) block masonry walls

Abstract The current research presents a novel and sustainable load-bearing system utilizing cellular lightweight concrete block masonry walls. These blocks, known for their eco-friendly properties and increasing popularity in the construction industry, have been studied extensively for their physical and mechanical characteristics. However, this study aims to expand upon previous research by examining the seismic performance of these walls in a seismically active region, where cellular lightweight concrete block usage is emerging. The study includes the construction and testing of multiple masonry prisms, wallets, and full-scale walls using a quasi-static reverse cyclic loading protocol. The behavior of the walls is analyzed and compared in terms of various parameters such as force–deformation curve, energy dissipation, stiffness degradation, deformation ductility factor, response modification factor, and seismic performance levels, as well as rocking, in-plane sliding, and out-of-plane movement. The results indicate that the use of confining elements significantly improves the lateral load capacity, elastic stiffness, and displacement ductility factor of the confined masonry wall in comparison to an unreinforced masonry wall by 102%, 66.67%, and 5.3%, respectively. Overall, the study concludes that the inclusion of confining elements enhances the seismic performance of the confined masonry wall under lateral loading

Evaluation of mechanical properties of cored interlocking blocks – A step toward affordable masonry material

This research study is about the evaluation of mechanical properties of locally prepared Cored 6” self-interlocking blocks. Currently, all the construction practices, whether brick masonry, block masonry, or reinforced concrete, are time consuming, relatively energy inefficient, not eco-friendly, and non-sustainable. Another issue in masonry construction is that the strength and behavior of bricks or blocks masonry depend upon the properties of the binding material (mortar) used in masonry wall joints. Considering these issues, Eco Blocks are newly introduced interlocking blocks with different sizes and shapes. Construction with interlocking blocks is faster, economical, and easier, as they do not require binding material. The aim of this study was to obtain the mechanical properties such as the compressive strength (individual block and prism), diagonal tensile strength, shear parameters, modulus of elasticity, shear modulus, and flexural strength of Cored 6′′ Eco Blocks through comprehensive experimental investigation. These showed encouraging results as compared with typical interlocking compressed earth blocks and also satisfied the threshold set forth by the international standards regulating earth construction. The compressive and flexural strengths of the blocks have been obtained as 6.03 MPa and 1.66 MPa, respectively. Based on the results outcomes, Cored 6” Eco Blocks can be utilized in load bearing walls

Complexes of 2-Amino-3-methylpyridine and 2-Amino-4-methylbenzothiazole with Ag(I) and Cu(II): Structure and Biological Applications

Coordination complexes (1–4) of 2-amino-4-methylbenzothiazole and 2-amino-3-methylpyridine with Cu(CH3COO)2 and AgNO3 were prepared and characterized by UV/Vis and FT-IR spectroscopy. The molecular structure for single crystals of silver complexes (2 and 4) were determined by X-ray diffraction. The coordination complex (2) is monoclinic with space group P21/c, wherein two ligands are coordinated to a metal ion, affording distorted trigonal geometry around the central Ag metal ion. The efficient nucleophilic center, i.e., the endocyclic nitrogen of the organic ligand, binds to the silver metal. Ligands are coordinated to adopt cis arrangement, predominantly due to steric reasons. The O(2) and O(3) atoms of the NO3− group further play an important role in such type of ligand arrangement by hydrogen bonding with the NH2 group of ligands. Complex (4) is orthorhombic, P212121, comprising two molecules of 2-amino-3-methylpyridine as ligand coordinated with the metal ion, affording a polymeric structure. The coordination behavior of the ligand is identical to that in complex 2, wherein ring nitrogen is coordinated to the metal center and bridged to another metal ion through an NH2 group. The resulting product is polymeric in nature with the Ag metal in the backbone and ligand as the bridge. Compounds (2–4) were found to be luminescent, while 1 did not show such activity. All compounds were screened for their preliminary biological activities such as antibacterial, antioxidant and enzyme inhibition. Compounds exhibited moderate activity in these tests

Polynuclear Cu(I) and Ag(I) Complexes of 1,3-Diisobutyl Thiourea, Synthesis, Crystal Structure and Antioxidant Potentials

Reaction of the 1,3-diisobutyl thiourea (L) with MX [M = Cu, Ag and X = Cl, NO3] provide polynuclear heteroleptic complexes [Cu3L3Cl3] (1), [Ag2L6](NO3)2 (2) and [Ag6L8Cl4] (3). All complexes were characterized by single crystal X-ray diffraction. The solid-state crystal of these complexes (1–3) were determined by single crystal XRD. Which shows that complex (1) is tri-nuclear with trigonal planer arrangement, complex (2) is binuclear with four membered metalacyclic ring and complex (3) is hexa-nuclear. Complexes (1–3) are tested for their free radical scavenging activity by using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) showing moderate potential