Terms Of Workability Research Articles

Factors associated with work ability among employees of an Italian university hospital

BackgroundA growing body of evidence clearly documents the benefits of integrated systems approaches to protecting and promoting the safety, health and well-being of workers. The purpose of this study is to provide a holistic view of the work ability of employees of an Italian University Hospital measuring their resources in relation to job demands. In particular, it examines socio-demographics, family and organizational antecedents of health professionals’ work ability.MethodsA survey was conducted to assess the work ability of healthcare professionals, including physicians, nurses and administrative staff, working at the University Hospital of Modena (Italy). The data collection allows us to get a sample of 443 workers, who correspond to 11% of the target population. The data were analyzed using preliminary statistics on the main characteristics of the sample in terms of work ability, socio-demographic variables, family and organizational characteristics. In addition, logit models of the likelihood of having high work ability were estimated using SPSS version 25.ResultsWork ability decreases with increasing age, comorbidity, high body mass index, having at least one child under 5 and/or a dependent adult, having a poor work-life balance, and doing more than 20 h of housework. Specific job resources can significantly promote work ability, including relationship-oriented leadership, autonomy in decision making and individuals’ skill match. The nursing profession is associated with a low work ability. Finally, a significant gender gap has been documented. Women find it more difficult to reconcile life and work, especially when they have children of preschool age and work in professions with greater responsibilities, as in the case of women doctors, who experience lower work capacity.ConclusionsOur results suggest that it is necessary to consider other factors, in addition to age, that are equally relevant in influencing work ability. Consequently, organisational interventions could be implemented to improve the work ability of all workers. In addition, we propose targeted interventions for groups at risk of reduced work capacity, in particular older workers (45 years and over), nurses, women with children of preschool age and in the position of physician.

Work Ability, Anxiety, and Depression among Long-Term Breast Cancer Survivors of Northern Kerala, India; A Historical Cohort Study.

Increasing number of breast cancer cases, and improved survival due to advancements in early detection, and treatment resulted in an increase in women living beyond a cancer diagnosis. Survivors have to face long-term physical effects as well as psychosocial issues post-treatment. This study aims to study survivourship in terms of work ability, anxiety and depression. Retrospective cohort study on female breast cancer survivors from Hospital Based Cancer Registry (HBCR) of a Tertiary Cancer Centre (TCC). Data from 2016 (n=534) were collected from the medical records, and a follow-up survey (n=209) was conducted in 2022 to study their survivorship issues. In 2022, the mean age of the cohort (n=209) was 55.45 ± 9.36. The mean work ability score was 40.7±5.73 (95% CI 39.92 to 41.48). In the multivariate binary logistic regression model, those who were married (OR 7.15, 95%CI 2.61 to 19.55), disease-free (OR 15.27, 95% CI 2.36 to 98.7), employed (OR 9.09, 95%CI 1.12 to 73.5), having no fatigue (OR 2.6, 95% CI 1.05 to 6.48), no pain (OR 3.11, 95% CI 1.16 to 8.35), and no depression (OR 6.58, 95% CI 1.82-23.8) were found to have optimal work ability. Anxiety (OR 4.93, 95% CI 1.76 to 13.76), and sub-optimal work ability (OR 4.22, 95% CI 1.39 to 12.77) were predictors of depression among survivors. Disease status and fatigue were associated with all three dimensions of survivorship in our study. Understanding survivorship will help improve health outcomes in this population. In our study, work ability, anxiety, depression, and their associated factors were found to be interrelated. Interventions in these areas can go a long way in improving breast cancer survivorship.

Use of cellulose nanomaterials in cementitious composites reinforced with basalt/polymer pellets for repair of concrete

Using cellulose nanomaterials (nano-crystalline [NC] and/or nano-fibrillated [NFC] cellulose) with a high content of supplementary cementitious materials and special class of basalt fiber/polymer (BFP) pellets could produce sustainable and resilient composites for a suite of infrastructure applications. Hence, this study investigated the development of cementitious composites comprising high content slag (50% as cement replacement), BFP (4.5% by volume), NFC ranging from 0 to 0.5% (addition to the mass of the binder) and NC (0 to 0.1% addition to the mass of the binder) to prepare multiple formulations without/with nano-silica (reference nanomaterial) for repair/overlay applications of concrete flatwork. An integrated experimental program including constructability, mechanical capacity, and durability properties as well as compatibility with substrate concrete was conducted. Findings of these tests were corroborated with thermal and microstructural tests to evaluate the hydration/pozzolanic development and pore structure features. The overall results indicated that the development of high-cementitious composites with cellulose nanomaterials is possible, as they achieved balanced behaviour in terms of workability, hardening rates, high early- and later-age compressive strengths, high ductility, improved durability, and superior thermal and elastic integrity/compatibility with the parent/normal concrete. Thus, they may present an attractive option for repair and overlay applications of concrete flatwork.

Bioactives and Technological Quality of Functional Biscuits Containing Flour and Liquid Extracts from Broccoli By-Products.

Broccoli by-products are an important source of health-promoting bioactive compounds, although they are generally underutilized. This study aimed to valorize non-compliant broccoli florets by transforming them into functional ingredients for biscuit formulation. A broccoli flour and three water/ethanol extracts (100:0, 75:25, 50:50; v/v) were obtained. The rheological properties and the content of bioactive compounds of the functional ingredients and biscuits were evaluated. The 50:50 hydroalcoholic extract was the richest in glucosinolates (9749 µg·g-1 DW); however, the addition of a small amount strongly affected dough workability. The enrichment with 10% broccoli flour resulted the best formulation in terms of workability and color compared to the other enriched biscuits. The food matrix also contributed to protecting bioactive compounds from thermal degradation, leading to the highest total glucosinolate (33 µg·g-1 DW), carotenoid (46 µg·g-1 DW), and phenol (1.9 mg GAE·g-1 DW) contents being present in the final biscuit. Therefore, broccoli flour is a promising ingredient for innovative healthy bakery goods. Hydroalcoholic extracts could be valuable ingredients for liquid or semi-solid food formulation.

Comparison of the Effect of Nano Cellulosic Additives on Rheological Parameters for 3D Printable Concretes

In 3D printable concretes, fresh requirements such as pumpability, workability, constructability are affected by the rheological properties of the mixture. High yield stress and high viscosity cause blockages in the transmission line, while low yield stress and low viscosity cause the mixture to not provide the required shape stability. Even if the mixture to be printed has suitable rheological parameters, it is very important in terms of workability that it can be preserved over time. Here, cellulose nanocrystals and cellulose nanofibers were used in cement paste mixtures in order to ensure sufficient workability time in 3D printable concrete mixtures, and also to ensure that the originally designed rheological properties can be maintained over time. The Bingham model, which was created as a result of the measurements made with the viscometer device, was used to evaluate the rheological parameters of the mixes containing cellulose nanocrystal and cellulose nanofiber additions in varied amounts. As a result of the study, it was determined that the yield stress of the reference sample increased by 290% 45 minutes after the preparation of the mixture, while this rate decreased to 135% in the use of cellulose nanocrystals and to 79% in the use of cellulose nanofibers. While it increased by 205% at the end, this rate decreased to 37% with cellulose nanofibers and to 68% with cellulose nanocrystals. When the different additives are compared, it was concluded that cellulose nanofiber may be more effective than cellulose nanocrystal in controlling the increase in viscosity and yield stress over time.

Effect of the Alkyl Density of Acrylic Acid Ester on the Viscosity-Reducing Effect of Polycarboxylate Superplasticizer.

Concrete is vital for the development of modern buildings. However, they suffer from the high viscosity problem in their application process due to the use of a low water-cement ratio in order to maintain their high strength. Developing PCEs with the presence of ester functional groups in their molecular structure is one of the most effective measures to improve the flowability of concrete. Here, three PCEs with different alkyl densities of acrylic acid ester: PCE-M, PCE-E, and PCE-B were designed to explore their viscosity-reducing effect on the performance of cement and concrete. The structures of the three PCEs were characterized via Fourier transform infrared (FTIR) spectra, proton nuclear magnetic resonance (1H NMR), and gel permeation chromatography (GPC). Their properties were also determined via zeta potential, surface tension, and rheological experiments. It was found that PCE-M had the best performance, with the lowest surface tension, highest zeta potential, and therefore highest charge density on the cement particles, lowest viscosity, and highest flowability of cement paste, and exhibited the best performance of concrete in terms of workability. The best performance of PCE-M in reducing the viscosity of cement and concrete can be ascribed to the smallest amount of water-repellent alkyl groups, enhancing the electrostatic repulsion and reducing the viscosity, thereby boosting the dispersion and stabilization of cement pastes and concrete. This study shed lights on designing other PCEs with high viscosity-reducing effects via an ester group control.

Diagnostic methods and ways of testing the workability of coal - a review

Abstract The need to classify rocks in terms of workability stems primarily from the need to choose the appropriate, most effective diagnostic method (DM) and way of mining the given rock. Studying and measuring the workability of rocks is extremely difficult due to the fact that workability depends on many various factors. There are many DM for determining the workability of rocks, but none of them take into account the influence of all factors, hence the obtained results are only indicative. In the article, many DM and ways of determining the cutting resistance with the use of various devices are presented and characterized. The principles of their operations are presented, as well as the DM of measuring the cutting resistance and its utilitarian usefulness in forecasting the selection of mining machines on the basis of cutting for specific mining and geological conditions. The core of the problem is confirmed by the number of covered DM and tools in various research centers around the world. In the article, new tools measuring and evaluating the mechanical properties of the coal solid, all created in Poland, are presented. Their structure, principles of their operation, as well as the innovation of these solutions, are all presented. In this article, their ad-vantages and disadvantages are highlighted, as well as showing the DM which best represents the way of work of the winning machine. Therefore, the results achieved through the aforementioned DM can be understood as representative values.

Mechanical Properties of PVC Fiber-Reinforced Concrete—Effects of Fiber Content and Length

This paper presents the key mechanical properties of PVC fiber-reinforced concrete. Six concrete mixtures were produced using plastic fibers obtained from clear PVC sheets. Three concrete mixtures were made using 20 mm long PVC fibers, whereas the other three were prepared with 40 mm long PVC fibers. The fiber content was varied in the range of 0–1.5 wt.% of cement for each length of fiber. The fresh concrete mixtures were tested for workability in terms of the slump. The hardened concretes were tested for their compressive and splitting tensile strengths, flexural strength and toughness, static elastic modulus, and impact resistance and toughness. The effects of the fiber content and fiber length on the workability and above-mentioned mechanical properties were observed. In addition, the correlations between various mechanical properties were sought. The test results revealed that the workability of concrete was reduced for both fiber lengths as the fiber content increased. The compressive strength, flexural strength and toughness, elastic modulus, and impact resistance and toughness increased at up to 1 wt.% fiber content, then decreased for 1.5 wt.% fibers. A similar trend was also noticed for the splitting tensile strength, particularly in the case of 20 mm long PVC fibers. Compared to the fiber length, the fiber content exhibited a more pronounced effect on the mechanical properties of concrete. The optimum fiber content was 1 wt.%, which produced the best performance in this study. Furthermore, excellent correlations were observed for the tested mechanical properties of concrete, except for splitting tensile strength, which was not well-correlated with compressive strength.

The Effects of Silica Fume and Superplasticizer Type on the Properties and Microstructure of Reactive Powder Concrete.

This paper deals with the optimization of reactive powder concrete mixtures with respect to the addition of silica fume and the type of polycarboxylate superplasticizer used. First, the properties of reactive powder concrete with eight different commercial polycarboxylate superplasticizers were tested in terms of workability, specific weight, and mechanical properties. It was found that different commercially available superplasticizers had significant effects on the slump flow, specific weight, and compressive and flexural strengths. The optimal superplasticizer (BASF ACE430) was selected for further experiments in order to evaluate the influences of silica fume and superplasticizer content on the same material properties. The results showed that the silica fume and superplasticizer content had considerable effects on the mini-cone slump flow value, specific weight, flexural and compressive strengths, and microstructure. There were clearly visible trends and local minima and maxima of the measured properties. The optimal reactive powder concrete mixture had a composition of 3.5-4.0% superplasticizer and 15-25% silica fume.

Assessment of Strength of Concrete containing ESP and IESP as Partial Cement Replacement

In the present era of technically feasible and environmentally compatible low-cost material substitution with the basic ingredients of conventional concrete mix, the infusion of eggshell powder in its raw as well as incinerated forms was tried with the cement mantle. Experimentations carried out to endorse the compressive strength, split tensile strength, flexural strength, workability and durability aspects revealed that it had the edge over the properties standardized for the conventional concrete mix at a specific mix strength of 20 MPa. The experimental results for variations in the treatments of eggshell powder and incinerated eggshell powder corresponding to the responses on the evaluation parameters were compared with the conventional concrete mix by means of regression analysis and modelling. The regression model at more than 95% correlation level of the experimental data fortified the relative supremacy of eggshell powder and incinerated eggshell powder-infused concrete mixes over the conventional concrete mix in terms of workability, strength, and durability. Based on the statistical regression point of inflexion and the point of tolerance, it was clearly established that 20% optimal proportional addition of eggshell powder or 30% addition of incinerated eggshell powder could result in a superlative performance compared to the conventional concrete mix. This final outcome of the optimal combinations of eggshell powder and incinerated eggshell powder incorporated concrete (EPIC) was also test verified by SEM and EDAX analyses.

Physicomechanical Behavior of High-Performance Concrete Reinforced with Recycled Steel Fibers from Twisted Cables in the Brittle State—Experimentation and Statistics

This research studied the effect of recycled steel fibers extracted from twisted cable waste on the fresh and hardened states of high-performance concretes. Accordingly, slump, water absorption (WA), compressive strength (CS), flexural strength (FS), and split tensile strength (STS) were measured in the laboratory using mixtures generated by the response surface methodology (RSM). The RSM-based central composite design (CCD) was used to assess the influence of water-to-binder (W/B) ratios from 0.27 to 0.31, length-to-diameter (L/d = 46 to 80) and steel fiber content (SFC) in the range of 19 to 29 kg/m3 on the behavior of high-performance fiber-reinforced concrete (HPFRC). The accuracy and validation of the generated models were evaluated by employing analysis of variance (ANOVA) and optimal parameters. The experimental findings revealed that the use of an L/d ratio of 63, a W/B ratio of approximately 0.28, and an SFC of around 22 kg/m3 resulted in high workability in terms of slump. While a notable increase in compressive strength was observed when employing an L/d ratio of approximately 70, a W/B ratio of around 0.28, and the maximum SFC of 29 kg/m3, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.

Physico-Mechanical Properties and High-Temperature Resistance of Gypsum-Based Colored Foam Concretes

In this paper, foam concrete was produced using gypsum material at a dosage of 500 kg/m3 as binder and 75 kg/m3 of foaming agent, and gypsum-based colored foam concrete (GBCFC) with dry unit weights below 1100 kg/m3 was obtained by using 5% coloring pigment during the production phase. Fresh state, physical, mechanical and high temperature resistance properties of the produced GBCFCs were tested. The spread diameters of the produced GBCFCs vary between 173 and 155 mm. 28-day compressive strengths vary between 7.8 and 2.7 MPa. Capillary water absorption values vary between 3.2 and 2.2 kg/m2. The weight loss after high temperature varies between 4.86 and 21.57%, while the compressive strength varies between 6.9 and 0.2 MPa. In the production of foam concrete to be used for wall and roof insulation, decorative panels and fire prevention, etc., the use of gypsum instead of cement as a binder and the coloring process during the production of foam concrete with pigment reduces the costs and the amount of CO2 emitted to nature, providing an economically positive and environmentally friendly composite production. The process of coloring this composite with pigment during the production phase has been proven by laboratory experiments to have positive effects in terms of workability and positive contributions in terms of mechanical and some durability properties.

Engineering properties of concrete incorporating waste glass as natural sand substitution with tin can fiber: experimental and ANN application

Disposal of waste material is causing environmental issues all around the world. Waste glass and tin can are two such products that impose detrimental effects on the environment. One feasible approach is to utilize these discarded materials as constituents of concrete. This study investigates the performance of concrete prepared with glass waste as fine aggregate (GWA) and tin can fiber (TCF) in terms of workability, fresh density, compressive, and splitting tensile strength as desired concrete properties. An Artificial Neural Network (ANN) approach has been adopted for developing predictive models to simulate the impact of these waste materials on concrete properties. Experimental findings demonstrate that the worability of concrete mix decreases with increasing GWA and TCF contents in the mix. Increasing TCF percentages results in an increase in fresh density of concrete; however, a declining pattern in fresh density has been observed with increasing GWA percentage in the concrete mix. Compressive strength at all curing ages shows positive trends till 20% GWA and 1% TCF incorporation in concrete. Similar pattern has been observed for splitting tensile strength up to 10% GWA and 0.5% TCF. Constructed models are feasible for prediction of the desired concrete properties as verified by various statistical parameters. Sensitivity analysis reports that TCF has a greater influence on concrete properties than GWA.

Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads

The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures. Engineered geopolymer composite (EGC) is a promising material featured by eco-friendly, fast-setting and strain-hardening characteristics for emergent strengthening and construction. However, the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain. In this study, laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability, dry shrinkage, and mechanical properties in compression, tension and flexure. The experimental results showed that EGC containing PE fiber exhibited suitable workability, acceptable dry shrinkage and superior mechanical properties compared with other types of fibers. After that, a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements. The tests include autoclaved aerated concrete (AAC) masonry walls subjected to vented gas explosion, reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion. It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios. For AAC masonry walls and panels, with the existence of EGC, the integrity of specimens could be maintained, and their deflections and damage were significantly reduced. For plain concrete slabs, the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.

Durability analysis of partial replacement of ordinary Portland cement by white glass waste concrete

Concrete consists of cement, water, fine aggregate, coarse aggregate, and air. The cement manufacturing process is responsible for a large carbon dioxide emission. Therefore, several research have been conducted to find advantageous substitute materials, even if only partially. Waste glass emerges as an alternative because it is a non-biodegradable inert material, with a high recycling rate and low cost. Several studies on recycled glass as a partial substitute for cement in concrete have already been conducted in terms of workability, strength, and properties, but few have reviewed the durability properties of concrete incorporating glass waste. It is a fact that durability is of great importance for the performance of concrete, because compromising it can lead to the emergence of pathologies. This article aims to carry out a study on the durability of concrete with the replacement of cement by glass waste, to verify its performance in relation to conventional concrete, identifying the advantages that attest to its use in civil construction as an alternative to concrete to be used in buildings, whether in new constructions or in the process of rehabilitation or maintenance.

Optimization and Modelling the Mechanical Performance of Date Palm Fiber-Reinforced Concrete Incorporating Powdered Activation Carbon Using Response Surface Methodology.

Date palm fiber (DPF) has been reported to have many advantages when used in concrete, however, its major disadvantage is that it causes a reduction in compressive strength. In this research, powdered activated carbon (PAC) was added to cement in the DPF-reinforced concrete (DPFRC) to lessen the loss in strength. PAC has not been properly utilized as an additive in fiber reinforced concrete even though it has been reported to enhance the properties of cementitious composites. Response surface methodology (RSM) has also been utilized for experimental design, model development, results analysis, and optimization. The variables were DPF and PAC as additions each at proportions of 0%, 1%, 2%, and 3% by weight of cement. Slump, fresh density, mechanical strengths, and water absorption were the responses that were considered. From the results, both DPF and PAC decreased the workability of the concrete. DPF addition improved the splitting tensile and flexural strengths and reduced the compressive strength, and up to 2 wt% PAC addition enhanced the concrete's strength and lowered the water absorption. The proposed models using RSM were extremely significant and have excellent predictive power for the concrete's aforementioned properties. Each of the models was further validated experimentally and was found to have an average error of less than 5.5%. According to the results of the optimization, the optimal mix of 0.93 wt% DPF and 0.37 wt% PAC as cement additives resulted in the best properties of the DPFRC in terms of workability, strength, and water absorption. The optimization's outcome received a 91% desirability rating. The addition of 1% PAC increased the 28-day compressive strength of the DPFRC containing 0%, 1% and 2% DPF by 9.67%, 11.13% and 5.5% respectively. Similarly, 1% PAC addition enhanced the 28-day split tensile strength of the DPFRC containing 0%, 1% and 2% by 8.54%, 11.08% and 19.3% respectively. Likewise, the 28-day flexural strength of DPFRC containing 0%, 1%, 2% and 3% improved by 8.3%, 11.15%, 18.7% and 6.73% respectively with the addition of 1% PAC. Lastly, 1% PAC addition led to a reduction in the water absorption of DPFRC containing 0% and 1% DPF by 17.93% and 12.2% respectively.

Effects of the physical characteristics of foams on conditioned soil’s flow behavior: A case study

Earth pressure balance shield (EPBS) is the excavation technique responding to the technical construction complexity of the future line 16–1 of the Grand Paris Express project. Its principle is based on the capacity of the excavated ground to transmit the forces needed to counterbalance the earth and water pressures of the working face. Additives are injected into the soil; on the cutting wheel, in the excavation chamber and in the screw conveyor. Their role is to assure the soil conditioning by modifying the soil’s workability and its hydromechanical and rheological parameters. Therefore, the soil conditioning produces a plastic medium able to transmit the pressure to maintain the front face. In addition, as a second objective, the additives aim to overcome uncertainties in the soil. Depending on the case, the additives can reduce the clogging, internal friction, abrasiveness, and permeability of the soil. The additives can include water, surfactant, polymer and bentonite. The combination of water and surfactant with or without polymer produces the foam. In order to increase the excavation perfomance, laboratory prelimenary tests are performed to deduce the optimal foam parameters. Since no test measuring the foam characteristics is standardized yet, this article sums up the tests mostly used in foam characterisation; half-life measurements, rheological tests, microstructural observations. As for the conditioned soil, slump test is frequently used by the tunnelling industry to recommend the optimal soil conditioning parameters in terms of workability. This test has been adapted in this study and the results are verified by rheological tests, then compared to the real foam injection data used for the project and their effect on mechanical parameters. For a specific type of excavated soil, the quality (type) of foam recommended by the laboratory work falls into the same choice of additive based on in-situ tunnelling excavation data. These findings are explained by the foams characteristics. Therefore, a correlation between foam and the conditioned soil (sandy soil with silt and low percentage of clay) with foam is deduced at different levels: micro, meso and macro (real) scales.

Utilization of coal gangue power generation industry by-product CFA in cement: Workability, rheological behavior and microstructure of blended cement paste

Circulating fluidized bed fly ash (CFA), by-product of coal gangue power generation industry based on circulating fluidized bed combustion technology, differs from ordinary fly ash (OFA) in its physical and chemical properties. This paper aims to investigate the influences of CFA with three particle sizes on the workability and rheological properties of cement paste. The results show that untreated raw CFA (RCFA) can significantly degrade many properties of fresh cement paste. Directly using CFA as a mineral admixture in cement-based materials is not suitable in terms of workability. However, CFA through grinding methods can significantly mitigate the detrimental effect of CFA on the flowability of cement paste. When 15% ultrafine CFA (UCFA) was added, the cement paste exhibited relatively favorable workability and rheological properties. The rheological behavior of cement paste containing CFA with three particle sizes follow the shear thinning, which is in line with the modified Bingham model. Furthermore, the reasons for the impact of CFA on the microscopic level of cement workability are analyzed and discussed. The addition of CFA reduces the amount of free solution in the cement paste, leading to the formation of a flocculated structure and an increase in the thixotropic loop area. Based on the analysis of TOC, BET and TEM, it was determined that numerous polycarboxylate superplasticizer (PCE) molecules are adsorbed onto the rough and porous surface structure of CFA particles, hence the destructive ability of PCE to the flocculation structure caused by cement hydration is weakened. Therefore, the mechanism that CFA affecting the working performance of cement paste can be determined as: the adsorption of free water and PCE molecules.

Incorporation of high loss-on-ignition fly ash into high-strength mortar: Influence on short-term engineering properties

The re-utilization of fly ash (FA), a primary by-product of thermal power plants, in producing various types of sustainable construction materials has been studied by many researchers. The quality of FA varies depending on either the characteristics of coal or the combustion techniques. Most previous studies used FA with a low loss-on-ignition (LOI), while the use of FA with a high LOI in the production of construction materials is still limited. Finding ways to reusing of locally available FA in sustainable construction materials is crucial. Therefore, this study aims to investigate the effect of high LOI FA content on the short-term engineering properties of high-strength mortars (as a modified concept of reactive powder concrete) in terms of workability, fresh unit weight, compressive and flexural strengths, drying shrinkage, and thermal conductivity. The mortar mixtures were designed with a constant water-to-binder ratio of 0.24 and the 0–60% high LOI FA was used to replace cement (step increment of 15% by weight). Test results found that the substitution of cement with high LOI FA significantly affected the engineering properties of high-strength mortars. Increasing the high LOI FA content improved the workability while reducing fresh unit weight, mechanical strength, drying shrinkage, and thermal conductivity of high-strength mortars. Although the short-term properties of mortars were negatively affected by the incorporation of high LOI FA, the mortar samples containing 60% high LOI FA registered relatively high 28-day compressive and flexural strengths of about 34 and 6 MPa, respectively. In another aspect, using high LOI FA in the production of construction materials is beneficial in reducing the use of cement as well as limiting environmental pollution due to the disposal of this FA type, contributing to a greener environment toward a sustainable development goal.

Performance of high workability plaster mortar for water tanks

Cement sand mortar is frequently used as water proofing plaster layer for water retaining structures. However, the current practice of using standard mortar for plastering has shown to be infective due to observed leakages and low durability of some water retaining structures. In the effort of solving these problems, materials engineers have used artificial chemicals like Zypex to control leakages and improve durability with some success. This paper reports on a study done to address the use of high workability plaster mortar as a solution to meet serviceability requirements for water retaining structures. The study involved the development of mix ratios 1:2, 1:3 and 1:4 for standard mortar mixes and using the same mix ratios with different doses of super-plasticizer from 0.00% to 0.50%, testing all mortar mixes for physical properties then determining their performances. The performance of mortar mixes was investigated in terms of workability, unit weight, strength development, tensile strength and water absorption. The test results have indicated high performance and suitability of high workability mortar mixes forplastering water retaining structures.