Non-load Bearing Research Articles

Investigation on the Application of Plastic Fibres as Reinforcing Materials In Concrete

Reinforcing materials in concrete are employed to enhance the tensile strength because concrete is weak in tension. Existing reinforcing materials have inadequate ductility and inability to reduce concrete cancer (corrosion) which can be addressed by using plastic fibre because of high ductility and inertness. Hence, this research assessed the effect of plastic fibre as reinforcement in concrete. Polyethylene terephthalate materials were obtained from Aradaa Market, Ogbomoso, Nigeria and shredded into fibre size of 65 x 2 mm. The shredded fibre introduced into the concrete mix ratio 1:2:4 using 12 mm aggregate size at 0.5, 1.5 and 2.5% volume fraction of the total mass of the concrete composite. The workability of the concrete produced was assessed in the laboratory through slump test. Plastic fibre reinforced concrete cubes of size 150 x 150 x 150 mm and beams of size 100 x 100 x 500 mm were produced in line with British Standard 882, Part 1 specification. The compressive and flexural strengths of these reinforced concrete composites were examined with the compressive test machine and Universal Testing Machine after 28 days of curing. The crack examination test on plastic fibre reinforced concrete was also done with the use of crack comparator. The slump values varied from 3 – 60 mm height. Compressive strength of the cubes varied from 18.58 to 18.71, 8.18 to 8.22, and 2.22 to 2.27 N/mm for 0.5, 1.5 and 2.5 % volume fraction, respectively. The corresponding flexural strength test values of the beams ranged from 23.95 to 24.01, 12.01 to 12.07 and 4.94 to 5.80 N/mm’, respectively. The crack examination test revealed crack width of 0.05 mm on the plain (0% fibre) concrete cubes while those with fibre reinforcement showed no cracks. Fibres reinforcement at 0.5% volume fraction improved the compressive and flexural strengths and reduced cracks of concrete. Shredded plastic fibres can be successfully used in many construction applications of light weight, non-load bearing and infill panels.

A numerical study on improving the specific properties of staggered composites by incorporating voids

Despite being porous, natural materials such as bone, nacre and tooth enamel possess interesting combinations of stiffness, strength and toughness, an outstanding performance which is hard to achieve in engineering materials. Recent studies show that this performance is rooted in their architectures in which stiff and strong inclusions are arranged in a staggered structure and placed within a softer matrix. These studies however focus on void-free staggered composites. Here, we use finite element analysis and exhaustive exploration of the design space to show that the specific modulus and yield strength of staggered composites can be improved by removing the non-load bearing regions of the matrix material and to show the morphologies emerging from this process. This improvement increases with aspect ratio of the inclusions and with mismatch of properties between the phases and decreases with inclusion content. Particularly, 20–30% increase in the specific modulus and 10–20% increase in specific yield strength can be achieved considering the actual properties of carbon nanotube (or ceramic/mineral platelet) reinforced polymers. The morphologies emerging from our exploration can be used to develop lightweight composites of interest in aerospace, defence, and packaging industries.

Investigating the fire performance of LSF wall systems using finite element analyses

PurposeThis research was aimed at investigating the fire performance of LSF wall systems by using 3-D heat transfer FE models of existing LSF wall system configurations.Design/methodology/approachThis research was focused on investigating the fire performance of LSF wall systems by using 3-D heat transfer finite element models of existing LSF wall system configurations. The analysis results were validated by using the available fire test results of five different LSF wall configurations.FindingsThe validated finite element models were used to conduct a parametric study on a range of non-load bearing and load bearing LSF wall configurations to predict their fire resistance levels (FRLs) for varying load ratios.Originality/valueFire performance of LSF wall systems with different configurations can be understood by performing full-scale fire tests. However, these full-scale fire tests are time consuming, labour intensive and expensive. On the other hand, finite element analysis (FEA) provides a simple method of investigating the fire performance of LSF wall systems to understand their thermal-mechanical behaviour. Recent numerical research studies have focused on investigating the fire performances of LSF wall systems by using finite element (FE) models. Most of these FE models were developed based on 2-D FE platform capable of performing either heat transfer or structural analysis separately. Therefore, this paper presents the details of a 3-D FEA methodology to develop the capabilities to perform fully-coupled thermal-mechanical analyses of LSF walls exposed to fire in future.

Investigation on potential reuse of textile sludge as fertiliser and for preparation of solid blocks

Sludge management practices are more important and becoming global challenge for effective reuse and safe disposal of sludge. Common effluent treatment plant is a cost effective option for treating textile wastewater from various units which is facing problem in sludge management. Reuse of chemical sludge for construction purposes is a suitable alternative for waste disposal. This study examines characterisation of chemical sludge and the suitability of chemical sludge for replacing cement (5%, 10%, 20%, 30%, 40% and 50%) in preparation of solid blocks. The preparation and testing of solid blocks were carried out as per ASTM and BIS standards. It is inferred from the results that the maximum of 30% chemical sludge used in solid blocks meets all requirements specified in ASTM non-load bearing and BIS load bearing standards. Experimental results of bio sludge revealed that the soil with 1% bio sludge addition was more suitable for the plant growth.

Effect of doping (Mg,Mn,Zn) on the microstructure and mechanical properties of spark plasma sintered hydroxyapatites synthesized by mechanical alloying

Although hydroxyapatite based bioceramics exhibit excellent bioactivity, their poor mechanical properties limit their applications to primarily as non-load bearing components and surface coating. The current investigation is aimed to mitigate this problem. In the present study, nanocrystalline undoped and 5mol% Mn, Mg and Zn-doped HAp powders are synthesized by mechanical alloying at room temperature. All as-milled samples are subsequently sintered at 950°C using spark plasma sintering (SPS) process to retain the nanocrystalline grains during sintering. Microstructural characterization in terms of lattice imperfections and relative phase abundances in both as-milled and sintered samples are done by analyzing respective XRD patterns employing Rietveld's structure and microstructure refinement method. For all HAp compounds, ~97% of theoretical density has been achieved after powder compaction into pellets by SPS without significant grain growth. Mechanical properties such as, hardness, elastic modulus, fracture toughness and brittleness index of the sintered and polished pellets are measured using Vickers microhardness tester with varying load up to 1kg. Significant improvements in the mechanical properties of doped HAp pellets are noticed with 220% increase in fracture toughness for Mn doped sample. The experimental results are interpreted by the changes in structure and microstructure parameters of both undoped and doped HAp samples.

Setting kinetics and mechanical properties of flax fibre reinforced glass ionomer restorative materials.

Regardless of the excellent properties of glass ionomer cements, their poor mechanical properties limit their applications to non-load bearing areas. This study aimed to investigate the effect of incorporated short, chopped and randomly distributed flax fibers (0, 0.5, 1, 2.5, 5 and 25 wt%) on setting reaction kinetics, and mechanical and morphological properties of glass ionomer cements. Addition of flax fibers did not significantly affect the setting reaction extent. According to their content, flax fibers increased the compressive (from 148 to 250 MPa) and flexure strength (from 20 to 42 MPa). They also changed the brittle behavior of glass ionomer cements to a plastic one. They significantly reduced the compressive (from 3 to 1.3 GPa) and flexure modulus (from 19 to 14 GPa). Accordingly, flax fiber-modified glass ionomer cements could be potentially used in high-stress bearing areas.

Acidic ammonothermal growth of gallium nitride in a liner-free molybdenum alloy autoclave

This paper discusses promising materials for use as internal, non-load bearing components as well as molybdenum-based alloys for autoclave structural components for an ammonothermal autoclave. An autoclave was constructed from the commercial titanium–zirconium–molybdenum (TZM) alloy and was found to be chemically inert and mechanically stable under acidic ammonothermal conditions. Preliminary seeded growth of GaN was demonstrated with negligible incorporation of transition metals (including molybdenum) into the grown material (<1017cm−3). Molybdenum and TZM were exposed to a basic ammonothermal environment, leading to slight degradation through formation of molybdenum nitride powders on their surface at elevated temperatures (T>560°C). The possibility of a ‘universal’, inexpensive, liner-free ammonothermal autoclave capable of exposure to basic and acidic chemistry is demonstrated.

Axial compressive behavior of FRP-confined lightweight aggregate concrete: An experimental study and stress-strain relation model

Due to its low strength and high brittleness, lightweight aggregate concrete (LWAC) can mainly be used to fabricate non-load bearing structures. Wrapping LWAC with fiber-reinforced polymer (FRP) can effectively improve its mechanical properties, thereby allowing to realize a structural lightweight design. This study therefore aimed to investigate the effect of a FRP confinement on the mechanical properties of LWAC. Three types of coarse aggregate material, i.e., class 600 shale ceramsite, class 800 shale ceramsite and hollow sealed thin-wall steel balls, were selected to design the LWAC and compared in the experiments. After wrapping with three layers of FRP, the strengths of LWACs prepared from the three different materials were improved by a factor of 2.6, 2.1 and 5.4, respectively, whereas their ultimate deformations were improved by a factor of 33.4, 8.5 and 31.2, respectively. Meanwhile, the strength and stress-strain relation for the FRP-confined LWAC were obtained through axial compression tests. Models for the ultimate strength, the ultimate strain and the stress-strain relation of FRP-confined LWAC were successfully established, and a comparative analysis revealed that the predictions made using these models are very accurate. A numerical analysis of these models further showed that, for LWAC and normal concrete with the same strength and FRP confinement, the mechanical behavior was different and found to heavily depend on the FRP confinement aspect properties and the types of the light-weight aggregate.

Compressed Stabilized Earth Block: A Green Alternative for Non-load Bearing Building Block in Developing Countries like Bangladesh

Compressed Stabilized Earth Block: A Green Alternative for Non-load Bearing Building Block in Developing Countries like Bangladesh

A Critical Review on Non-Load Bearing Wall Based on Different Materials

A Critical Review on Non-Load Bearing Wall Based on Different Materials

Surface topography and mechanical properties of flax fibres modified glass ionomer restorative materials

Objectives: Regardless of the excellent adhesive and biological properties of glass ionomer cements (GICs), their poor mechanical properties and abrasion resistance limit their application to non-load bearing areas. This study aimed to investigate the effect of flax fibres incorporation on surface and mechanical properties of GIC filling materials. Methods: Short chopped flax fibres were randomly incorporated into GIC at 0, 0.5, 1, 2.5, 5 and 25 wt%. Surface hardness, distribution of different phases, stiffness map, phase separation and uniformity of the material were investigated. Results: Addition of flax fibres produced no significant change in Vicker hardness number of GIC. Qualitative imaging using atomic force microscopy showed the presence of a single phase in GIC, while biphasic structure was observed for flax fibres modified GICs (FFMGICs). For all tested formulations, the flax fibres, however, were uniformly distributed and well integrated within the GIC matrix without any visible interfacial separation. Incorporation of flax fibres was associated with a significant increase in surface roughness and stiffness. The roughness values obtained for all tested formulations, however, are far below the threshold values for bacterial adhesion and plaque accumulation. Conclusions: Flax fibres modified GICs could be potentially used in high stress bearing areas.

Comparative Studies of Steel, Bamboo and Rattan as Reinforcing Bars in Concrete: Tensile and Flexural Characteristics

This study comparatively evaluated the flexural performance and deformation characteristics of concrete elements reinforced with bamboo (Bambusa vulgaris), rattan (Calamuc deerratus) and the twisted steel rebars. The yield strength (YS), ultimate tensile strength (UTS) and the elongation of 50 specimens of the three materials were determined using a universal testing machine. Three beams of concrete strength 20 N/mm2 at age 28 days were separately reinforced with bamboo, rattan and steel bars of same percentage, while the stirrups were essentially mild steel bars. The beams were subjected to centre-point flexural loading according to BS 1881 to evaluate the flexural behaviour. The YS of bamboo and rattan bars were 13% and 45% of that of steel respectively, while their UTS were 16% and 62% of that of steel in the same order. The elongation of bamboo, rattan and steel were 7.42%, 10% and 14.7% respectively. The natural rebars were less than the 12% minimum requirement of BS 4449. The load-deflection plots of bamboo and steel RC beams were quadratic, while rattan RC beams had curvilinear trend. The stiffness of bamboo RC beams (BB) and rattan RC beams (RB) were 32% and 13.5% of the stiffness of steel RC beams (SB). The post-first crack residual flexural strength was 41% for BB and SB, while RB was 25%. Moreover, the moment capacities of BB and RB corresponded to 51% and 21% respectively of the capacity of steel RC beams. The remarkable gap between the flexural capacities of the natural rebars and that of steel can be traced not only to the tensile strength but also the weak bonding at the bar-concrete interface. It can be concluded that the bamboo bars are suitable rebars for non-load bearing and lightweight RC flexural structures, while more pre-strengthening treatment is required more importantly for rattan for improved interfacial bonding and load-carrying capacity.

Preparation and Characterization of Calcium-Magnesium Phosphate Cements

Calcium phosphate cements (CPCs) have been widely used as bone substitute materials. However, their degradation property is insufficient to stimulate bone healing in large bone defects, besides, the poor initial mechanical strength limits their application to non-load bearing areas. In this study, to overcome the drawbacks of CPCs, magnesium phosphate cements (MPCs) characterized by high initial strength and relatively rapid degradation were combined with CPCs to develop novel calcium-magnesium phosphate cements (CMPCs). The morphology of the CPC sample consisted of needle-like crystals, whereas the interlinked hemispherical globules were observed for the CMPCs. The handling and mechanical characteristics of the samples as well as their degradation behavior under in vitro condition were investigated. Results showed that the CMPCs exhibited shorter setting time and higher compressive strength than the CPC. In addition, CMPCs showed significatnly improved degradability compared to the CPC in Tris-HCl buffer solution.

Fracture analysis of randomized implant-supported fixed dental prostheses

ObjectiveFractures of posterior fixed dental all-ceramic prostheses can be caused by one or more factors including prosthesis design, flaw distribution, direction and magnitude of occlusal loading, nature of supporting infrastructure (tooth root/implant), and presence of adjacent teeth. This clinical study of implant-supported, all-ceramic fixed dental prostheses, determined the effects of (1) presence of a tooth distal to the most distal retainer; (2) prosthesis loading either along the non-load bearing or load bearing areas; (3) presence of excursive contacts or maximum intercuspation contacts in the prosthesis; and (4) magnitude of bite force on the occurrence of veneer ceramic fracture. Methods89 implant-supported FDPs were randomized as either a three-unit posterior metal–ceramic (Au–Pd–Ag alloy and InLine POM, Ivoclar, Vivadent) FDP or a ceramic–ceramic (ZirCAD and ZirPress, Ivoclar, Vivadent) FDP. Two implants (Osseospeed, Dentsply) and custom abutments (Atlantis, Dentsply) supported these FDPs, which were cemented with resin cement (RelyX Universal Cement). Baseline photographs were made with markings of teeth from maximum intercuspation (MI) and excursive function. Patients were recalled at 6 months and 1–3 years. Fractures were observed, their locations recorded, and images compared with baseline photographs of occlusal contacts. ConclusionNo significant relationship existed between the occurrence of fracture and: (1) the magnitude of bite force; (2) a tooth distal to the most distal retainer; and (3) contacts in load-bearing or non-load-bearing areas. However, there was a significantly higher likelihood of fracture in areas with MI contacts only. Clinical significanceBecause of the absence of a periodontal ligament, this clinical study demonstrates that there is a need to evaluate occlusion differently with implant-supported prostheses than with natural tooth supported prostheses. Implant supported prostheses should have minimal occlusion and lighter contacts than those supported by natural dentition. Clinical Trials.gov NoK23 D2007-46.

Research Summary of Vibration Reducing Performance for Infilled Wall

Infilled wall is always regarded as a nonload bearing element, its energy-dissipation capacity and impact for the frame structure under earthquake have not been taken seriously. In this paper the function of infilled wall for frame structure was discussed, energy-dissipation capacity of different measures were analysed and compared from the point of passive control theory. This paper provides the reference for the further research of filler wall.

Structural Glass Fiber Reinforced Concrete for Slabs on Ground

This paper aims to contribute to the classification and specification of glass fiber reinforced concrete (GFRC) and to deal with the question if structural glass fiber reinforced concrete as a special kind of glass fiber reinforced concrete is suited for use in load-bearing members. Despite excellent material properties, the use of glass fibers in a concrete matrix is carried out so far only in non- structural elements or as a modification for the prevention of shrinkage cracks. The aim of re- search at the University of Applied Sciences in Leipzig is the use of alkali-resistant macro glass fibers as concrete reinforcement in structural elements as an alternative to steel fiber reinforcement. Slabs on ground, as an example for structural members, provide a sensible application for the new material because they can be casted as load bearing and non-load bearing and are mostly made of steel fiber reinforced concrete. In the future, structural glass fiber reinforced concrete shall provide a simple and visually appealing alternative to conventional steel bar or steel fiber reinforced concrete. The glass fibers can also be used in combination with conventional reinforcing bars or mat reinforcements. Initial investigations have announced some potential.

Recycled Polymer Materials as Aggregates for Concrete and Blocks

The potential of recycled waste polymeric materials as a substitute for aggregates in concrete has been investigated in the study. Two different types of waste polymer, namely polyurethane formaldehyde (PUF) based packaging waste and high density polyethylene (HDPE) were recycled and used in the experiment. Concrete and masonry poly block specimens were prepared using recycled polymer materials, and test specimens were characterized. The effects of waste polymer materials on the mechanical, physical and morphological properties of concrete and poly blocks have been investigated. The result shows that the inclusion of waste polymer materials decreases density, porosity and water absorption of concrete and poly blocks significantly. Polyurethane formaldehyde (PUF) based block exhibited lower density than that of HDPE-based concrete. Due to exceptionally low density, recycled polymer modified blocks and concrete can be used in non-load bearing structures, floating structures and where light weight materials recommended. DOI: http://dx.doi.org/10.3329/jce.v27i1.15859 Journal of Chemical Engineering, IEB Vol. ChE. 27, No. 1, June 2012: 53-57

Sustainability assessment of an innovative lightweight building technology for partition walls – Comparison with conventional technologies

The growing necessity to save material and energy resources, together with an increasing concern over the environmental issues and uncertainties on the evolution of the economy, have impelled minimalist-approaches to Architecture and Engineering. This created a new necessity for reducing, to the minimum necessary expression, the used building materials and elements. When analysing the overall material inputs of a building, it is possible to conclude that the interior partition walls have the higher contribution to the material inputs, when compared to other non-load bearing construction elements. Other aspect to highlight is that a great portion of building designs are not flexible in use and therefore buildings are not suitably adjustable to the permanent updating of life-styles and variations on the composition of the households. Although there are some lightweight building technologies, in most cases the construction practice all over Europe makes use of heavyweight and static partition walls. This paper will focus the advantages of lightweight partition walls and may contribute for the development of new partition wall technologies. It presents a sustainability assessment of a new lightweight sandwich membrane building technology for indoor partitions developed within a research project. The used methodology comprises the environmental, functional and economic life-cycle analysis. In order to identify the advantages of the building technology under development, each different design approach for the conceptual technology will be compared with two reference technologies: i) the heavyweight conventional partition wall (hollow brick wall); and ii) the lightweight reference gypsum panels wall (plasterboard wall).

Utilization of andesite processing wastewater treatment sludge as admixture in concrete mix

The dried physicochemical sludge from the coagulation–flocculation treatment of an andesite processing plant wastewater was used as concrete admixture in powder form. Various physicochemical sludges obtained with various coagulant/flocculants (alum, FeCl3, and sepiolite) were experienced dry particulate (powder) form of the sludge was replaced at 0.5–1.5% w/w of the cement for 250kg/m3 cement dosage. The admixture doses were complied with local standard. Slump tests were conducted on fresh concrete, and compressive strengths were measured for 7 and 28days hardened concrete samples. Physical properties, namely freeze/thaw resistance, water absorption, capillary suction, void ratio and porosity were determined at the end of 28days for the hardened concrete samples. The concrete consistency (slump) was improved up to 16–18cm from 14.5cm by the admixture. The best compressive strength was achieved with 0.5% w/w for admixtures. The admixture sludges obtained with organic flocculants were worse than the other admixtures. The structural changes after freeze/thaw tests were very close to the reference concrete (concrete without admixture); only the capilary suction had increased. The results confirmed that up to 0.5% of physicochemical sludge can be replaced with cement in concrete for use in certain non-load bearing structures that require medium strength concrete.

T1ρ mapping of pediatric epiphyseal and articular cartilage in the knee

To evaluate the feasibility of measuring T1ρ values in epiphyseal cartilage in children, we have conducted a novel study of spin locking techniques. Adult articular cartilage has been widely studied with spin locking techniques by magnetic resonance imaging. However, no results are available for in vivo T1ρ imaging of developing cartilage. Ten volunteers of age 6 ± 3 years were recruited to have T1ρ mapping performed on the knee at the conclusion of their clinical study. T1ρ maps were generated using a spin-lock cluster followed by a fast spin-echo imaging sequence. Regions of interest (ROIs) were placed in non-load-bearing (NLB), load-bearing (LB), and articular cartilage. Student's t-tests were performed to compare means among the ROIs. Mean T1ρ for epiphyseal and articular cartilage was 49.8 ± 9 and 76.6 ± 7 ms, respectively. LB and NLB T1ρ vales were 47.1 ± 9.5 and 52.5 ± 9 ms, respectively. Significant differences were found in T1ρ values between epiphyseal and articular cartilage layers (P = 0.0001). No difference in T1ρ was observed between NLB and LB layers. A modest trend was also noted for epiphyseal and articular cartilage regions with age. It is feasible to quantify differences in epiphyseal and articular cartilage layers with SL techniques. T1ρ holds promise as a noninvasive method of studying normal and abnormal developmental states of cartilage in children.