Review of the progress in thin bed technology for masonry construction

Thin bed technology for clay/ concrete masonry is gaining popularity in many parts of the developed economy in recent times through active engagement of the industry with the academia. One of the main drivers for the development of thin bed technology is the progressive contraction of the professional brick and block laying workforce as the younger generation is not attracted towards this profession due to the general perception of the society towards manual work as being outdated in the modern digital economy. This situation has led to soaring cost of skilled labour associated with the general delay in completion of construction activities in recent times. In parallel, the advent of manufacturing technologies in producing bricks and blocks with adherence to specified dimensions and shapes and several rapid setting binders are other factors that have contributed to the development of thin bed technology. Although this technology is still emerging, especially for applications to earthquake prone regions, field applications are reported in Germany for over a few decades and in Italy since early 2000. The Australian concrete masonry industry has recently taken keen interest in pursuing research with a view to developing this technology. This paper presents the background information including review of literature and pilot studies that have been carried out to enable planning of the development of thin bed technology. The paper concludes with recommendations for future research.

Thin bed masonry system: review and future prospects

Masonry is one of the most ancient construction materials in the World. When compared to other civil engineering practices, masonry construction is highly labour intensive, which can affect the quality and productivity adversely. With a view to improving quality and in light of the limited skilled labour in the recent times several innovative masonry construction methods such as the dry stack and the thin bed masonry have been developed. This paper focuses on the thin bed masonry system, which is used in many parts of Europe. Thin bed masonry system utilises thin layer of polymer modified mortars connecting the accurately dimensioned and/or interlockable units. This assembly process has the potential for automated panelised construction system in the industry setting or being adopted in the site using less skilled labour, without sacrificing the quality. This is because unlike the conventional masonry construction, the thin bed technology uses thinner mortar (or glue) layer which can be controlled easily through some novel methods described in this paper. Structurally, reduction in the thickness of the mortar joint has beneficial effects; for example it increases the compressive strength of masonry; in addition polymer added glue mortar enhances lateral load capacity relative to conventional masonry. This paper reviews the details of the recent research outcomes on the structural characteristics and construction practices of thin bed masonry. Finally the suitability of thin bed masonry in developing countries where masonry remains as the most common material for residential building construction is discussed.

Effects of wearing a pressure redistribution belt while lying in a hospital bed

Bedsores (ulcers) are caused by multiple factors which include, but are not limited to; pressure, shear force, friction, temperature, age and medication. Specialised support services, such as specialised mattresses, sheepskin coverings etc., are thought to decrease or relieve pressure, resulting in a lowering of pressure ulcer incidence [3]. The primary aim of this study was to compare the upper/central body pressure distribution between normal lying in a hospital bed versus the use of a pressure redistribution belt. The study involved 16 healthy voluntary subjects lying on a hospital bed with and without wearing the belt. Results showed that the use of a pressure redistribution belt results in reduced pressure peaks and prevents the pressure from increasing over time.

Effectiveness of powered hospital bed movers for reducing physiological strain and back muscle activation

Battery powered bed movers are becoming increasingly common within the hospital setting. The use of powered bed movers is believed to result in reduced physical efforts required by health care workers, which may be associated with a decreased risk of occupation related injuries. However, little work has been conducted assessing how powered bed movers impact on levels of physiological strain and muscle activation for the user. The muscular efforts associated with moving hospital beds using three different methods; manual pushing, StaminaLift Bed Mover (SBM) and Gzunda Bed Mover (GBM)were measured on six male subjects. Fourteen muscles were assessed moving a weighted hospital bed along a standardized route in an Australian hospital environment. Trunk inclination and upper spine acceleration were also quantified. Powered bed movers exhibited significantly lower muscle activation levels than manual pushing for the majority of muscles. When using the SBM, users adopted a more upright posture which was maintained while performing different tasks (e.g. turning a corner, entering a lift), while trunk inclination varied considerably for manual pushing and the GBM. The reduction in lower back muscular activation levels and the load reducing effect of a more upright posture may result in lower incidence of lower back injury.

Assessing ease of use of the Staminalift bed mover

Battery powered bed movers are increasingly being used within the hospital setting. These energy augmenting devices facilitate the safe movement of beds and patients by healthcare workers. The use of powered bed movers is believed to result in reduced physical efforts on the behalf of staff members, which may be associated with a decreased risk of occupational related injuries. A provisional study was performed in a hospital environment to assess the muscular efforts associated with moving hospital beds both manually and with the aid of a bed mover. The results enable the effects of using bed movers to be quantified.

Characterisation of flexural bond strength in thin bed concrete masonry

This paper presents an experimental investigation of the flexural bond strength of thin bed concrete masonry. Flexural bond strength of masonry depends upon the mortar type, the techniques of dispersion of mortar and the surface texture (roughness) of concrete blocks. There exists an abundance of literature on the conventional masonry bond containing 10mm thick mortar; however, the 2mm polymer flue mortar bond is not yet well researched. This paper reports a study on the examination of the effect of mortar compositions, dispersion methods and unit surface textures to the flexural bond strength of thin bed concrete masonry. Three types of polymer modified glue mortars, three surface textures and four techniques of mortar dispersion have been used in preparing 108 four point flexural test specimens. All mortar joints have been carefully prepared to ensure achievement of 2mm layer polymer mortar thickness on average. The results exhibit the flexural bond strength of thin bed concrete masonry much is higher than that of the conventional masonry; moreover the unit surface texture and the mortar dispersion methods are found to have significant influence on the flexural bond strength.

Fixed bed pyrolysis of date seed waste for liquid oil production

The conversion of biomass waste in the form of date seed into pyrolysis oil by fixed bed pyrolysis reactor has been taken into consideration in this study. A fixed bed pyrolysis has been designed and fabricated for obtaining liquid fuel from these date seeds. The major component of the system are fixed bed pyrolysis reactor, liquid condenser and liquid collector. The date seed in particle form is pyrolysed in an externally heated 7.6 cm diameter and 46 cm high fixed bed reactor with nitrogen as the carrier gas. The reactor is heated by means of a biomass source cylindrical heater from 4000C to 6000C. The products are oil, char and gas. The reactor bed temperature, running time and feed particle size are considered as process parameters. The parameters are found to influence the product yield significantly. A maximum liquid yield of 50 wt.% is obtained at a reactor bed temperature of 5000 C for a feed size volume of 0.11- 0.20 cm3 with a running time of 120 minutes. The pyrolysis oil obtained at this optimum process conditions are analyzed for some fuel properties and compared with some other biomass derived pyrolysis oils and also with conventional fuels. The oil is found to possess favorable flash point and reasonable density and viscosity. The higher calorific value is found to be 28.636 MJ/kg which is significantly higher than other biomass derived pyrolysis oils.

Design and construction of fixed bed pyrolysis system and plum seed pyrolysis for bio-oil production

This work investigated the production of bio oil from plum seed (Zyziphus jujuba) by fixed bed pyrolysis technology. A fixed bed pyrolysis system has been designed and fabricated for production of bio oil. The major components of the system are: fixed bed reactor, liquid condenser and liquid collector. Nitrogen gas was used to maintain the inert atmosphere in the reactor where the pyrolysis reaction takes place. The feedstock considered in this study is plum seed as it is available waste material in Bangladesh. The reactor is heated by means of a cylindrical biomass external heater. Rice husk was used as the energy source. The products are oil, char and gas. The parameters varied are reactor bed temperature, running time and feed particle size. The parameters are found to influence the product yields significantly. The maximum liquid yield of 39 wt% at 5200C for a feed particle size of 2.36-4.75 mm and a gas flow rate of 8 liter/min with a running time of 120 minute. The pyrolysis oil obtained at these optimum process conditions are analyzed for some of their properties as an alternative fuel. The density of the liquid was closer with diesel. The viscosity of the plum seed liquid was lower than that of the conventional fuels. The calorific value of the pyrolysis oil is one half of the diesel fuel.

Fixed bed pyrolysis of pulm seed waste for liquid oil production

Among various thermo-chemical conversion processes, pyrolysis is considered as an emerging technology for liquid oil production. The conversion of biomass waste in the form of plum seed into pyrolysis oil by fixed bed pyrolysis reactor has been taken into consideration in this study. A fixed bed pyrolysis has been designed and fabricated for obtaining liquid fuel from this plum seeds. The major component of the system are fixed bed pyrolysis reactor, liquid condenser and liquid collectors. The plum seed in particle form is pyrolysed in an externally heated 7.6 cm diameter and 46 cm high fixed bed reactor with nitrogen as the carrier gas. The reactor is heated by means of a biomass source cylindrical heater from 4000C to 6000C. The products are oil, char and gas. The reactor bed temperature, running time and feed particle size are considered as process parameters. The parameters are found to influence the product yield significantly. A maximum liquid yield of 39 wt% of biomass feed is obtained with particle size of 2.36-4.75 mm at a reactor bed temperature of 520oC with a running time of 120 minutes. The pyrolysis oil obtained at this optimum process conditions are analyzed for some fuel properties and compared with some other biomass derived pyrolysis oils and conventional fuels. The oil is found to possess favorable flash point and reasonable density and viscosity. The higher calorific value is found to be 22.39 MJ/kg which is higher than other biomass derived pyrolysis oils.

‘I always look under the bed for a man’. Needs and barriers to the expression of sexuality in residential aged care: the views of residents with and without dementia

Objectives: This qualitative study canvassed residents' perceptions of the needs and barriers to the expression of sexuality in long-term care. Methods: Sixteen residents, including five with dementia, from six aged care facilities in two Australian states were interviewed. Data were analysed using a constant comparative method. Results: Four categories describe residents' views about sexuality, their needs and barriers to its expression: ‘It still matters’; ‘Reminiscence and resignation’, ‘It's personal’, and ‘It's an unconducive environment’. Discussion: Residents, including those with dementia, saw themselves as sexual beings and with a continuing need and desire to express their sexuality. The manner in which it was expressed varied. Many barriers to sexual expression were noted, including negative attitudes of staff, lack of privacy and limited opportunities for the establishment of new relationships or the continuation of old ones. Interviewees agreed that how a resident expressed their sexuality was their business and no one else's.

Effect of reactive bed mineralogy on arsenic retention and permeability of synthetic arsenic-containing acid mine drainage

Successive alkalinity producing systems (SAPSs) are widely used for treating acid mine drainage (AMD) and alleviating clogging commonly occurring in limestone systems due to an amorphous ferric precipitate. In this study, iron dust, bone char, micrite and their admixtures were used to treat arseniccontaining AMD. A particular interest was devoted to arsenic removal performance, mineralogical constraints on arsenic retention ability and permeability variation during column experiment for 140 days. The results showed that the sequence of the arsenic removal capacity was as follows: bone char > micrite > iron dust. The combination of 20% v/v iron dust and 80% v/v bone char/micrite columns can achieve better hydraulic conductivity and phosphorus-retention capacity than single micrite and bone char columns. The addition of iron dust created reductive environment and resulted in the transformation of coating material from colloidal phase to secondary mineral phase, such as green rust and phosphoerrite, which obviously ameliorates hydraulic conductivity of systems. The sequential extraction experiments indicated that the stable fractions of arsenic in columns were enhanced with help of iron dust compared to single bone char and micrite columns. A combination of iron dust and micrite/bone char represented a potential SAPS for treating As-containing AMD.

Lesions in the bed nucleus of the stria terminalis disrupt corticosterone and freezing responses elicited by a contextual but not by a specific cue-conditioned fear stimulus

The bed nucleus of the stria terminalis (BNST) is believed to be a critical relay between the central nucleus of the amygdala (CE) and the paraventricular nucleus of the hypothalamus in the control of hypothalamic–pituitary– adrenal (HPA) responses elicited by conditioned fear stimuli. If correct, lesions of CE or BNST should block expression of HPA responses elicited by either a specific conditioned fear cue or a conditioned context. To test this, rats were subjected to cued (tone) or contextual classical fear conditioning. Two days later, electrolytic or sham lesions were placed in CE or BNST. After 5 days, the rats were tested for both behavioral (freezing) and neuroendocrine (corticosterone) responses to tone or contextual cues. CE lesions attenuated conditioned freezing and corticosterone responses to both tone and con- text. In contrast, BNST lesions attenuated these responses to contextual but not tone stimuli. These results suggest CE is indeed an essential output of the amygdala for the expres- sion of conditioned fear responses, including HPA re- sponses, regardless of the nature of the conditioned stimu- lus. However, because lesions of BNST only affected behav- ioral and endocrine responses to contextual stimuli, the results do not support the notion that BNST is critical for HPA responses elicited by conditioned fear stimuli in general. Instead, the BNST may be essential specifically for contex- tual conditioned fear responses, including both behavioral and HPA responses, by virtue of its connections with the hippocampus, a structure essential to contextual condition- ing. The results are also not consistent with the hypothesis that BNST is only involved in unconditioned aspects of fear and anxiety.

State-of-the-art of the Australian thin bed concrete structural masonry

With a view to minimising the spiraling labour costs, the concrete masonry industry is developing thin layer mortar technology (known as thin bed technology) collaboratively with Queensland University of Technology. Similar technologies are practiced in Europe mainly for clay brick masonry; in the UK thin layer mortared concrete masonry has been researched under commercial contract with limited information published. This paper presents numerous experimental data generated over the past three years. It is shown that this form of masonry requires special drymixed mortar containing a minimum of 2% polymer for improved workability and blocks with tighter height tolerance, both of which might increase the cost of these constituent materials. However, through semiskilled labour, tools to dispense and control the thickness of mortar and the associated increase in productivity, reduction to the overall costs of this form of construction can be achieved. Further the polymer mortar provides several advantages: (1) improved sustainability due to dry curing and (2) potential to construct mortar layers of 2mm thickness and (3) ability for mechanisation of mortar application and control of thickness without the need for skilled labour.