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The purpose of this paper is to investigate the effect of the replacement of natural coarse aggregate (NCA) with different percentages of recycled coarse aggregate (RCA) on properties of low calcium fly ash (FA)-based geopolymer concrete (GPC) cured at oven temperature. Further, this paper aims to study the effect of partial replacement of FA by ground granulated blast slag (GGBS) in GPC made with both NCA and RCA cured under ambient temperature curing.

M25 grade of ordinary Portland cement (OPC) concrete was designed according to IS: 10262-2019 with 100% NCA as control concrete. Since no standard guidelines are available in the literature for GPC, the same mix proportion was adopted for the GPC by replacing the OPC with 100% FA and W/C ratio by alkalinity/binder ratio. All FA-based GPC mixes were prepared with 12 M of sodium hydroxide (NaOH) and an alkalinity ratio, i.e. sodium hydroxide to sodium silicate (NaOH:Na₂SiO₃) of 1:1.5, subjected to 90^°C temperature for 48 h of curing. The NCA were replaced with 50% and 100% RCA in both OPC and GPC mixes. Further, FA was partially replaced with 15% GGBS in GPC made with the above percentages of NCA and RCA, and they were given ambient temperature curing with the same molarity of NaOH and alkalinity ratio.

The workability, compressive strength, split tensile strength, flexural strength, water absorption, density, volume of voids and rebound hammer value of all the mixes were studied. Further, the relationship between compressive strength and other mechanical properties of GPC mixes were established and compared with the well-established relationships available for conventional concrete. From the experimental results, it is found that the compressive strength of GPC under ambient curing condition at 28 days with 100% NCA, 50% RCA and 100% RCA were, respectively, 14.8%, 12.85% and 17.76% higher than those of OPC concrete. Further, it is found that 85% FA and 15% GGBS-based GPC with RCA under ambient curing shown superior performance than OPC concrete and FA-based GPC cured under oven curing.

The scope of the present paper is limited to replace the FA by 15% GGBS. Further, only 50% and 100% RCA are used in place of natural aggregate. However, in future study, the replacement of FA by different amounts of GGBS (20%, 25%, 30% and 35%) may be tried to decide the optimum utilisation of GGBS so that the applications of GPC can be widely used in cast in situ applications, i.e. under ambient curing condition. Further, in the present study, the natural aggregate is replaced with only 50% and 100% RCA in GPC. However, further investigations may be carried out by considering different percentages between 50 and 100 with the optimum compositions of FA and GGBS to enhance the use of RCA in GPC applications. The present study is further limited to only the mechanical properties and a few other properties of GPC. For wider use of GPC under ambient curing conditions, the structural performance of GPC needs to be understood. Therefore, the structural performance of GPC subjected to different loadings under ambient curing with RCA to be investigated in future study.

The replacement percentage of natural aggregate by RCA may be further enhanced to 50% in GPC under ambient curing condition without compromising on the mechanical properties of concrete. This may be a good alternative for OPC and natural aggregate to reduce pollution and leads sustainability in the construction.

The present work focuses on evaluating the physical and mechanical characteristics of geopolymer concrete (GPC) by replacing the sodium silicate waste (SSW) in place of traditional river sand. The aim is to create eco-friendly concrete that mitigates the depletion of conventional river sand and conserves natural resources. Additionally, the study seeks to explore how the moisture content of filler materials affects the performance of GPC.

SSW obtained from the sodium silicate industry was used as filler material in the production of GPC, which was cured at ambient temperature. Instead of the typical conventional river sand, SSW was substituted at 25 and 50% of its weight. Three distinct moisture conditions were applied to both river sand and SSW. These conditions were classified as oven dry (OD), air dry (AD) and saturated surface dry (SSD).

As the proportion of SSW increased, there was a decrease in the slump of the GPC. The setting time was significantly affected by the higher percentage of SSW. The presence of angular-shaped SSW particles notably improved the compressive strength of GPC when replacing a portion of the river sand with SSW. When exposed to elevated temperatures, the performance of the GPC with SSW exhibited similar behavior to that of the mix containing conventional river sand, but it demonstrated a lower residual strength following exposure to elevated temperatures.

Exploring the possible utilization of SSW as a substitute for river sand in GPC, and its effects on the performance of the proposed mix. Analyzing, how varying moisture conditions affect the performance of GPC containing SSW. Evaluating the response of the GPC with SSW exposed to elevated temperatures in contrast to conventional river sand.

This study aims to practically determine the optimum proportion of aggregates to attain the desired strength of geopolymer concrete (GPC) and then compare the results using established analytical particle packing methods. The investigation further aims to assess the influence of various amounts of recycled aggregate (RA) on properties of low-calcium fly ash-based GPC of grade M25.

Fine and coarse aggregates were blended in various proportions and the proportion yielding maximum packing density was selected as the optimum proportion and they were compared with analytical models, such as Modified Toufar Model (MTM) and J. D. Dewar Model. RAs for this study were produced in laboratory and they were used in various amounts, namely, 0%, 50% and 100%. 12M NaOH solution was mixed with Na₂SiO₃ in the ratio of 1:2. The curing of concrete was done at the temperatures of 60° and 90 °C for 24, 48 and 72h.

The experimentally obtained optimum proportion of coarse to fine aggregate was 60:40 for all amounts of RA. Meanwhile, MTM and Dewar Model resulted in coarse aggregate to fine aggregates as 40:60, 45:55, 55:45 and 55:45, 35:65, 60:40, respectively, for 0% 100% and 50% RAs. The compressive strength of GPC elevated with the increase in curing regime. In addition, the ultrasonic pulse velocity also displayed a similar trend as that of strength.

The GPC with 50% RAs may be considered for use, as it exhibited superior properties compared to GPC with 100% RAs and was comparable to GPC with natural aggregates. Furthermore, compressive strength is correlated with split tensile strength and ultrasonic pulse velocity.

Organizational climates reflect employee perceptions of the way organizational culture is actualized and most studies explore one or two climates only. The present study uses a positive organizational behavior approach and conservation of resources theory to explore a global positive climate (GPC) encompassing five climates: perceive organizational support, psychosocial safety climate, organizational mindfulness, worthy work and inclusion climate. The GPC is used to predict employee engagement and job satisfaction, with psychological capital as a mediator. Beyond this, high performance work systems (HPWS) are included as a moderator of GPC to test the potential way HR practices might interact with positive climates to achieve superior outcomes.

A large sample (n = 1,007) of New Zealand workers across a wide range of occupations and industries. Confirmatory factor analysis (CFA) of the data was used and moderated mediation tests were conducted.

GPC is significantly related to psychological capital, employee engagement and job satisfaction, and while psychological capital also predicts the outcomes, and has some mediation effects on GPC influence, GPC remains significant. HPWS is significantly related to psychological capital only and interacts with GPC leading to the highest psychological capital and employee engagement. Significant moderated mediation effects are found, with the indirect effect of GPC increasing as HPWS increase.

This research is important because it provides empirical evidence around a GPC and shows how organizations and HRM managers can enhance key employee attitudes through building a strong climate and providing important HR practices.

Beyond unique effects from GPC, the findings provide useful theoretical insights toward conservation of resources theory.

Concrete is a building material widely used for the infrastructural development. Cement is the binding material used for the development of concrete. It is the primary cause of CO₂ emission globally. The purpose of this study is to develop sustainable concrete material to satisfy the present need of construction sector. Geopolymer concrete (GPC) is a sustainable concrete developed without the use of cement. Therefore, investigations are being conducted to replace the cement by 100% with high calcium fly ash (FA) as binding material.

High calcium FA is used as cementitious binder, sodium hydroxide (NaOH) and sodium silicates (Na₂SiO₃) are used as alkaline liquids for developing the GPC. Mix proportions with different NaOH molarities of 4, 6, 8 and 10 M are considered to attain the appropriate mix. The method of curing adopted is ambient and oven curing. Workability, compressive strength and microstructure characteristics of GPC are analysed and presented.

An increase of NaOH in the mix decreases the workability. Compressive strength of 29 MPa is obtained for Mix-I with 8 M under ambient curing. A polynomial relationship is obtained to predict the compressive strength of GPC. Scanning electron microscope analysis is used to confirm the geo-polymerisation process in the microstructure of concrete.

This research work focuses on finding some alternative cementitious material for concrete that can replace ordinary portland cement (OPC) to overcome the CO₂ emission owing to the utilisation of cement in the construction industry. An attempt has been made to use the waste material (high calcium FA) from thermal power plant for the production of GPC. GPC concrete is the novel building material and alternative to conventional concrete. It is the ecofriendly product contributing towards the improvement of the circular economy in the construction industry. There are several factors that affect the property of GPC such as type of binder material, molarity of activator solution and curing condition. The novelty of this work lies in the approach of using locally available high calcium FA along with manufactured sand for the development of GPC. As this approach is rarely investigated, to prove the attainment of compressive strength of GPC with high calcium FA, an attempt has been made during the present investigation. Other influencing parameter which affects the strength gain has also been analysed in this paper.

This study aims to develop geopolymer concrete (GPC) using manufactured sand (M-sand) and recycled concrete aggregate (RCA) under different curing conditions. GPC is a sustainable construction material developed with industrial waste products such as fly ash to eliminate the use of cement in the production of concrete. GPC requires heat curing for the attainment of early age strength. The development of GPC under heat curing conditions is a hard process in practice. To overcome such circumstances, an attempt was made to develop the GPC under different curing conditions with the aid of coarse aggregate (CA) and RCA. The influence of different curing conditions on strength gain and microstructural characteristics of GPC is investigated. Mechanical properties of GPC such as compressive strength, tensile strength, flexural strength and elastic modulus are reported and discussed.

This study focuses on the assessment of mechanical and microstructure characterization of eco-efficient GPC developed with natural CA and RCAs. The required optimum quantity of binder, alkali activator, alkaline liquid to binder ratio and aggregates was determined by appropriate trials. Three types of curing methods, namely, ambient, oven and water, were used for the development of GPC mixes. Following the properties of RCA, it is realistic to substitute up to 40% of coarser aggregates as the resulting aggregate mix falls within the requirements of the analyzed mix.

Special attention is required for the mix with RCA because the mix’s consistency is affected by the high water absorption of the RCA mix. GPC specimens cured at ambient and water conditions exhibited marginal variation in the compressive strength for both CA and RCA. The compressive strength of GPC mixes prepared with RCA was marginally higher than that of the GPC made with CA under different curing regimes. RCA can be used as a sustainable material in lieu of CA in GPC.

The main significance of this research work is to develop the optimal mix design with appropriate mix proportion. The present study proposes a satisfactory methodology that enhances the mechanical strength of GPC as the guidelines are not available in the standards to address this problem. Effective use of waste materials such as fly ash and recycled aggregate for the development of GPC is another major research focus in the proposed investigation.

The purpose of this paper is to understand whether firms are driven by external pressure or intrinsic value to conduct green management; this study examines the effects of coercive pressure and ethical responsibility on cross-functional green strategy alignment (GSA) and green process coordination (GPC), and in turn, market and environmental performance.

Based on data from 206 Chinese manufacturers, this study empirically tests the proposed relationships using structural equation modeling.

The results highlight the role of coercive pressure in promoting both GSA and GPC that represent functional green efforts at both strategic and operational levels, indicating firms’ critical concern of obtaining external legitimacy from stakeholders. Ethical responsibility as an intrinsic value promotes GPC that demands joint working from different functions at the operational level. Besides, the authors find that GSA improves market and environmental performance, whereas GPC only enhances environmental performance.

This study adds to the knowledge of the drivers of cross-functional green management from external pressure and intrinsic value perspectives. The findings are also fruitful for practitioners and policymakers.

This review of the applications of gel permeation chromatography (GPC) in the paint and allied industries is based on a literature search which mainly covers the years 1978 to 1982 and follows on from previous similar review articles, the last of which was published in this journal in 1979. [R. A. Ellis, Pigment & Resin Technology 5(11),17–21 (1979)]. As the technique of GPC is chiefly applied to binder resins the article is once again divided into sections dealing with the specific chemical polymer species that are used as paint binders. There is also a section dealing with finished paints and another which attempts to bring together all that is novel in GPC practice. There is a considerable variation in the degree of sophistication that needs be applied to carry out this technique, and it is again very much in evidence from this literature survey how much valuable work can still be done with the simplest of chromatographic equipment. However, the degree of sophistication that can be achieved in GPC procedures in terms of setting up fully automated computer‐controlled systems, which require only that the sample be presented in a suitable state of solution for complete analysis and data processing, is also evident from this review.

Vinyl acetate was polymerised at −24°C, under an atmosphere of nitrogen and using an Hanovia 100‐W mercury arc lamp, by Atkinson et al. (2) who then subjected the product to preparative GPC using a Waters Associates AnaPrep chromatography unit fitted with columns (1.2m × 2.5cm dia. or 1.2m × 6.25cm dia.) that were packed with Styragel chosen to suit the MSD of the samples as previously determined in a separate analytical GPC run. Fractions from several runs, that were obtained by elution with toluene at a flow rate of 15mL min−1, were combined together prior to recovery of the polymer samples by freeze drying the solutions now in benzene. The Mn of each fraction so obtained was determined in toluene at 40°C using a Hewlett‐Packard model 502 osmometer fitted with Arro 450 special membranes.

The effects of catalysts used to promote the reaction of epoxy‐anhydride mixtures was studied by Nuss (77) using a GPC technique. It was demonstrated that when the polymerisation reaction occuring in an identical system was monitored, in the presence of different catalysts, the relationship between the apparent molecular size distribution and the lapsed time of the curing reaction was a function of the catalyst employed.