Moisture and Temperature Effects on Interface Mechanical Properties for External Bonding

In order to develop rational guidelines for strengthening by external bonding, it is necessary to clarify longterm performance of interfacial bonding property. In this paper, moisture effects on bonding properties at FRP–concrete interface and temperature/moisture effects on bonding properties at PCM–concrete interface are presented. Shear bond strength of FRP–concrete interface is affected by moisture because resin–concrete adhesion strength is affected by moisture. Among tested CFRP external bonding systems, wet-layup CFRP systems all show the strength reduction, while prefabricated CFRP systems all show the strength increase after immersion. The bond stress–slip relationship and interfacial fracture energy also change, which can explain the change in shear bond strength. The reduction in shear bond strength does not show clear dependency on resin strength/stiffness reduction. The observed big variation in shear bond strengths reported in past studies can be explained by difference in interface roughness, since chemical bond is affected by moisture but mechanical bond is not. Tension/shear bond strength of PCM–concrete interface is affected significantly by temperature but less by moisture. The tensile/shear bond strength is less than tensile/shear strength of constituent materials (PCM and concrete). The reduction in tension/shear bond strength depends on the reduction in tensile/shear strengths of PCM and concrete and then estimated by proposed equation which is a function of PCM and concrete strength. The ultimate loads of beams strengthened by PCM overlay can be predicted by the proposed model in which the proposed tensile/shear bond strength is applied. Under high temperature, the failure mode can be changed from flexure/shear failure to debonding failure due to the reduction in shear bond strength

Diabetic foot self-care: associated risk factors, awareness and practice among type II diabetic patients

Objective: To evaluate associated risk factors, awareness and practice level of diabetic foot self-care among type II diabetic patients.Methodology: A cross-sectional study was conducted at outpatient departments of Akbar khan Niazi teaching hospital and PIMS hospital from June to December, 2018. All adult patients diagnosed as Diabetes Mellitus (DM) type 2 for at least one year without any foot related complication were selected. The questionnaire included on demographics and questions related to diabetes, awareness and practice of foot self-care.Results: A total of 196 patients were enrolled, majority 116 (59.18%) of which had age of 41-60 years with 105 (53.57%) of male participants, 76 (38.78%) patients were illiterate and 93 (47.45%) were unemployed or retired. Majority of the participants 109 (55.61%) had monthly income of 25000-50000. Eighty-eight (44.90%) patients were overweight and 32 (16.33%) obese. Majority 113 (57.65%) had diabetes from 5-10 years. On the basis of HbA1c level only 58 (29.59%) patients had HbA1c level of less than 7.0%. Significant number of patients had poor knowledge (41.3%) and practice level (39.8%) regarding foot care.Conclusion: Almost half of our patients attending primary healthcare centers have limited awareness and practice regarding diabetic foot self-care

Diabetic foot self-care: associated risk factors, awareness and practice among type II diabetic patients

Objective: To evaluate associated risk factors, awareness and practice level of diabetic foot self-care among type II diabetic patients.Methodology: A cross-sectional study was conducted at outpatient departments of Akbar khan Niazi teaching hospital and PIMS hospital from June to December, 2018. All adult patients diagnosed as Diabetes Mellitus (DM) type 2 for at least one year without any foot related complication were selected. The questionnaire included on demographics and questions related to diabetes, awareness and practice of foot self-care.Results: A total of 196 patients were enrolled, majority 116 (59.18%) of which had age of 41-60 years with 105 (53.57%) of male participants, 76 (38.78%) patients were illiterate and 93 (47.45%) were unemployed or retired. Majority of the participants 109 (55.61%) had monthly income of 25000-50000. Eighty-eight (44.90%) patients were overweight and 32 (16.33%) obese. Majority 113 (57.65%) had diabetes from 5-10 years. On the basis of HbA1c level only 58 (29.59%) patients had HbA1c level of less than 7.0%. Significant number of patients had poor knowledge (41.3%) and practice level (39.8%) regarding foot care.Conclusion: Almost half of our patients attending primary healthcare centers have limited awareness and practice regarding diabetic foot self-care

高温下の材料および部材レベルでのコンクリートとPCMとの付着界面挙動

Strengthening, retrofitting, upgrading and rehabilitation of ageing infrastructure by Polymer Cement Mortar (PCM) is one of viable, economical and environment friendly solutions. Although PCM has superior properties than ordinary mortar in terms of mechanical strength, durability and good adhesive strength with concrete, the weakest zone in the concrete-PCM specimen is the interfacial zone. PCM after placing over treated substrate concrete surface is properly cured and after designed curing period, composite specimens/structures were exposed to severe environmental deterioration mechanisms. This fact causes the degradation of interface more rapidly than constituent materials and is responsible for significant reduction of intended service life of repaired structures. Therefore, it is necessary to investigate the behavior of interface under severe environmental conditions, which can be used for designing of repaired structures. For such aim, detailed experimental and analytical study were conducted, in which influence of moisture and temperature were investigated on composite specimens along with the constituents. Primary goal of this work is to strengthening of concrete structure in hot regions, where temperature increases to higher than 60 ℃ in peak summer. So environmental conditions were selected, which have resemblance to real environment. Day night variation and seasonal variation with short and long temperature duration were considered as exposure conditions. PCM and composite specimens were exposed to such conditions and were tested for interfacial tensile strength at designed conditions. Polymers from PCM were extracted after conducting interfacial split tensile strength test and tested for molecular weight, glass transition temperature and melting point. It was observed that testing condition significantly affected the tensile strength of PCM and composite specimens. Severe degradation at high temperature and recovery under lowering temperature were observed. Short temperature duration, about 16 hours, is long enough to have pronounced effect on tensile strength. Maximum reduction in tensile strength was observed under the combined action of temperature and moisture and tested at high temperature. Failure mode of composite specimen was shifted from adhesive interface failure to cohesive PCM at elevated temperature, which is considered as the indication of degradation of PCM. Whereas, molecular weight, glass transition temperature and melting point of polymers were still almost the same after different exposures. Because of the observed severe influence of moisture and temperature on interfacial tensile strength, more detailed experiments were designed, in which properties of bulk specimens and composite specimens were investigated under moisture and temperature variation separately and then combined variation. Tensile strength of concrete, PCM and concrete-PCM specimens was decreased with increase in temperature and moisture have only marginal effect. Degradation in tensile strength of PCM was significant at elevated temperature. Prediction formula of interfacial tensile strength was also proposed which was the function of the tensile strength of constituent materials and applicable for the temperature range from 20 ℃ to 60 ℃. Failure mode of all composite specimens under both types of environmental conditions was adhesive interface failure. To increase the interfacial strength, interfacial zone was enhanced by adding primer at interface and also by increasing the roughness level of substrate concrete surface. Along with interfacial tensile strength of bulk and composite specimens at elevated temperature, interfacial shear strength was also investigated for both types of specimens. Prediction formula of interfacial tensile strength was verified by incorporating the effect of primer and enhanced surface treatment. All data lies within ±10% of experimental results when compared with the predicted interfacial tensile strength. Prediction formula of interfacial shear strength was also proposed and applicable for temperature range of 20 ℃ to 60 ℃. Small variation was observed but average experimental data lies within ±10% of predicted results, which verifies the applicability of proposed formula. For real application of the current work, behavior of interface was also investigated at member level by conducting loading test of RC beams strengthened by PCM overlaying with different amount of reinforcement. All beams, strengthened and unstrengthened, were exposed to different temperature levels and tested at exposed temperature and humidity condition in four points loading test. Failure load of all strengthened beams were observed more than the unstrengthened beams but decreased with the increase in temperature level. Failure mode at elevated temperature was also varied from classical failure mode of conventional RC beam to debonding at overlay end as increase in the amount of reinforcement. Ductility, first crack load, yield load and ultimate load also decreased with the increase in temperature. Prediction model for debonding strength was proposed by incorporating interfacial tensile and shear strength of composite specimens, which were investigated at material level. Truss analogy approach was used for prediction of ultimate shear load and failure mode for overlay beams and close agreement was observed at all temperature levels. Serviceability of strengthened RC beams at elevated temperature was also investigated by investigating flexural crack spacing in constant moment zone at different temperature level and by measuring crack width at temperature level of 20 and 40 ℃. Crack spacing and crack width was increased with the increase in temperature

Influence of continuous and cyclic temperature durations on the performance of polymer cement mortar and its composite with concrete

Polymer cement mortar (PCM) is a widely used cementitious repairing material due to its considerable adhesive property with concrete. However, the polymers are sensitive to elevated temperatures. The behaviours of polymers and PCM at elevated temperatures (e.g., 60 degrees C) for short, moderate duration and cyclic conditions remain unknown and need to be explored. This work was aimed at studying the mechanical performance of PCM and PCM-concrete composites under the aforementioned exposure conditions. The bond strength in tension was evaluated by interfacial split tensile and flexural strength tests. A reduction in the mechanical strength of PCM was observed when exposed and tested at 60 degrees C, and the strength recovery was also observed after cooling the specimen. The cyclic temperature condition has the most detrimental influence on the mechanical behaviour of PCM and PCM-concrete interface compared to other exposure conditions. To reveal the damage mechanism, the polymers were extracted from the PCM, and the glass transition (T-g) and melting point temperatures were obtained by differential scanning calorimetry (DSC) analysis. Corresponding to the mechanical reduction of the PCM and interface, the reduction in the T-g value was also observed after elevated temperature and cyclic temperature exposure except the case exposed to moist condition. The maximum strength recovery was observed when the testing temperature was less than T-g . Besides, the molecular weight of the extracted polymers was analysed by gel permeation chromatography (GPC). The ratio of the area regarding the amount of oligomers to the area regarding the molecular weight of the GPC curve increased with the temperature duration, which was consistent with the tensile strength reduction of PCM

Leveraging Buyers’ Interest in ESG Investments through Sustainability Awareness

Currently, organizations often take into consideration the environmental, social, and governance (ESG) principles by following a more inclusive approach together with potential other emerging practices that attract more consumers who have particular affiliations with the environment. This study investigates the influence of social and environmental sustainability awareness practices on impulse buying through a proposed set of hypotheses. The hypothetical model is based on (441) valid responses from Omani buyers via an online research survey. Data were processed using CFA and SEM techniques. Results indicate that social and environmental sustainability awareness has a productive relationship with green trust that strengthens impulse buying. Environmental sustainability awareness positively links with green altruism, which further enhances the impulse. By taking gender as a moderator, it has an encouraging impact on social and environmental sustainability awareness. Environmental sustainability awareness and green altruism have a constructive relationship within males rather than females. Based on the unique connection between sustainability practices and impulse buying, the current study’s results indicate that if firms take appropriate steps to implement sustainability practices in their operations, sustainability commitment can promote the environmental and social well-being of consumers and the establishment of trust. Such practices enable companies to achieve their sustainability reporting goals and SDGs. Social and environmental sustainability practices protect from the harmful effects of social and environmental influences in mitigating the uncertainty of consumers’ buying behavior. Such productive sustainability practices compel buyers to purchase products impulsively at premium prices. The study strongly recommends policymakers and marketers focusing on environmental and social sustainability awareness and green altruism