Conversion of Waste Marble Powder into a Binding Material

In the marble industry, a lot of marble is wasted in the form of odd blocks of various sizes and slurry consisting of water and micro-fine particles. The slurry on drying converts into powder. Both slurry and powder have adverse effects on the environment. This research is focused on the gainful utilization of waste marble powder (WMP) by converting it into a valuable binding material. For this purpose, WMP and clay were collected, and their physical and chemical properties were determined. A mix of WMP and clay was prepared and burnt at a temperature around 1300 oC. The burnt mix was ground to powder form to get marble cement (MC). The MC was then used in mortar. The compressive and flexural strengths of mortar cubes and prisms were determined. Apart from this, X-ray diffraction (XRD) analysis, thermo-gravimetric analysis (TGA) and scanning electron microscopic (SEM) analysis were also carried out. The chemical composition showed that the MC has 52.5% di-calcium silicate (C2S) and 3.5% tri-calcium silicate (C3S).The  compressive strength of MC mortar after 28 days curing is 6.03 MPa, which is higher than M1 mortar of building code of Pakistan (5 MPa). The compressive strength of MC mortar after one year is 20.67 MPa, which is only 17% less than OPC mortar

Utilization of Marble Wastes in Clay Bricks: A Step towards Lightweight Energy Efficient Construction Materials

Marble dust is one of the hazardous byproducts of marble-processing factories and requires planned disposal. Its beneficial use as a construction material will add to the sustainability, and most importantly, might overcome the burden of marble waste disposal. However, the use of marble dust in concrete has a negative impact. Therefore, this research examines various properties related to the utilization of such material in ceramic clay, and therefore its effects on the use of clay bricks are investigated. The research activity covers the categorization of marble dust powder from three different sources: Ziarat in Mohmand Agency, Buneer, and Mullagori (Pakistan). Its utilization in different proportions preparation of bricks is also addressed. Through the partial replacement of clay with marble dust from 0 to 30% by weight with amplification of 5%, seven mix designs are examined. The test result includes Bulk density, water absorption, porosity, thermal insulation, and strength. The partial replacement of clay with marble dust reduced its weight, strength and increased its porosity, water absorption, and thermal insulation. Furthermore, the utilization of marble powder in bricks minimizes soil erosion and reduces pollution to the environment. Doi: 10.28991/cej-2021-03091738 Full Text: PD

The Effects of Osmosis and Thermo-Priming on Salinity Stress Tolerance in Vigna radiata L.

A plant’s response to osmotic stress is a complex phenomenon that causes many abnormal symptoms due to limitations in growth and development or even the loss of yield. The current research aimed to analyze the agronomical, physiological, and biochemical mechanisms accompanying the acquisition of salt resistance in the Vigna radiata L. variety ‘Ramzan’ using seed osmo- and thermopriming in the presence of PEG-4000 and 4 °C under induced salinity stresses of 100 and 150 mM NaCl. Seeds were collected from CCRI, Nowshera, and sowing was undertaken in triplicate at the Department of Botany, Peshawar University, during the 2018–2019 growing season. Rhizospheric soil pH (6.0), E.C (2.41 ds/m), field capacity, and moisture content level were estimated in the present study. We observed from the estimated results that the agronomic characteristics, i.e., shoot fresh weight and shoot dry weight in T9 (4oC + 150 mM NaCl), root fresh weight and root dry weight in T4 (PEG + 100 mM NaCl), shoot moisture content in T5 (PEG + 100 mM NaCl), and root moisture content in T6 (PEG + 150 mM NaCl) were the highest, followed by the lowest in T1 (both shoot and root fresh weights) and T2 (shoot and root dry weights). Similarly, the shoot moisture content was the maximum in T5 and the minimum in T6, and root moisture was the highest in T6. We observed from the estimated results that agronomical parameters including dry masses (T4, T6, T4), leaf area index, germination index, leaf area, total biomass, seed vigor index under treatment T9, and relative water content and water use efficiency during T5 and T6 were the highest. Plant physiological traits such as proline, SOD enhanced by T1, carotenoids in treatment T2, and chlorophyll and protein levels were the highest under treatment T4, whereas sugar and POD were highest under treatments T7 and T8. The principal component analysis enclosed 63.75% of the total variation among all biological components. These estimated results confirmed the positive resistance by Vigna radiata during osmopriming (PEG) and thermopriming (4 °C) on most of the features with great tolerance under a low-saline treatment such as T4 (PEG), T5 (PEG + 100 mM NaCl), T7 (4 °C), and T8 (4 °C + 100 mM NaCl), while it was susceptible in the case of T6 (PEG + 150 mM NaCl) and T9 (4 °C + 150 mM NaCl) to high salt application. We found that the constraining impact of several priming techniques improved low salinity, which was regarded as economically inexpensive and initiated numerous metabolic processes in plants, hence decreasing germination time. The current study will have major applications for combatting the salinity problem induced by climate change in Pakistan

The Effects of Osmosis and Thermo-Priming on Salinity Stress Tolerance in Vigna radiata L.

A plant’s response to osmotic stress is a complex phenomenon that causes many abnormal symptoms due to limitations in growth and development or even the loss of yield. The current research aimed to analyze the agronomical, physiological, and biochemical mechanisms accompanying the acquisition of salt resistance in the Vigna radiata L. variety ‘Ramzan’ using seed osmo- and thermopriming in the presence of PEG-4000 and 4 °C under induced salinity stresses of 100 and 150 mM NaCl. Seeds were collected from CCRI, Nowshera, and sowing was undertaken in triplicate at the Department of Botany, Peshawar University, during the 2018–2019 growing season. Rhizospheric soil pH (6.0), E.C (2.41 ds/m), field capacity, and moisture content level were estimated in the present study. We observed from the estimated results that the agronomic characteristics, i.e., shoot fresh weight and shoot dry weight in T9 (4oC + 150 mM NaCl), root fresh weight and root dry weight in T4 (PEG + 100 mM NaCl), shoot moisture content in T5 (PEG + 100 mM NaCl), and root moisture content in T6 (PEG + 150 mM NaCl) were the highest, followed by the lowest in T1 (both shoot and root fresh weights) and T2 (shoot and root dry weights). Similarly, the shoot moisture content was the maximum in T5 and the minimum in T6, and root moisture was the highest in T6. We observed from the estimated results that agronomical parameters including dry masses (T4, T6, T4), leaf area index, germination index, leaf area, total biomass, seed vigor index under treatment T9, and relative water content and water use efficiency during T5 and T6 were the highest. Plant physiological traits such as proline, SOD enhanced by T1, carotenoids in treatment T2, and chlorophyll and protein levels were the highest under treatment T4, whereas sugar and POD were highest under treatments T7 and T8. The principal component analysis enclosed 63.75% of the total variation among all biological components. These estimated results confirmed the positive resistance by Vigna radiata during osmopriming (PEG) and thermopriming (4 °C) on most of the features with great tolerance under a low-saline treatment such as T4 (PEG), T5 (PEG + 100 mM NaCl), T7 (4 °C), and T8 (4 °C + 100 mM NaCl), while it was susceptible in the case of T6 (PEG + 150 mM NaCl) and T9 (4 °C + 150 mM NaCl) to high salt application. We found that the constraining impact of several priming techniques improved low salinity, which was regarded as economically inexpensive and initiated numerous metabolic processes in plants, hence decreasing germination time. The current study will have major applications for combatting the salinity problem induced by climate change in Pakistan

Performance of Concrete Confined with a Jute–Polyester Hybrid Fiber Reinforced Polymer Composite: A Novel Strengthening Technique

The strengthening and rehabilitation of concrete members is an important issue which arises worldwide. Carbon, aramid and glass fiber reinforced polymer (FRP) composites are mainly used for strengthening and rehabilitation. However, its use is limited on a small scale because of its high price, lack of availability and environmental impacts. The solution of this issue gives rise to the use of locally available natural fibers and low-cost synthetic fibers. This paper presents the experimental and analytical results of circular and square concrete columns confined with jute–polyester hybrid FRP composites. The main objective of this study is to evaluate the viability and performance of concrete confined with the hybridization of jute and polyester (FRP) composite sheets to utilize its superior properties. A novel hybrid technique has been applied for the wrapping of fiber sheets. The fiber sheets were applied in such a way that a uniform bond between the inner and outer layer was achieved. A total of 32 plain, standard size circular and square concrete specimens, externally wrapped with a jute–polyester FRP (JPFRP) composite, were tested under monotonic axial compressive loads. The result shows that JPFRP confinement increased the strength, strain and ductility index ranged between 1.24 and 2.61, 1.38 and 8.97, and 4.94 and 26.5 times the un-jacketed specimen, respectively. Furthermore, the wrapping has a significant effect on the low-strength specimens, having a circular cross-section. For high strength specimens, the post-peak stress-strain behavior was dominated by the outer polyester jacket because of its large rupture strain. Additionally, the test results were used to evaluate the existing strength-strain models derived for conventional FRPs. The models predicted values either underestimating or overestimating the compressive strength and strain of JPFRP-confined specimens. However, the strength models performed better than the strain models. The JPFRP wrapping significantly enhanced the strength, fracture energy, ductility index, and post-peak response. Therefore, JPFRP confinement can be used for a small-scale application, where little strength and high ductility is demanded. Moreover, it can be used to prevent the peeling of the concrete cover and moisture penetration into the concrete

Evaluation of Mechanical and Microstructural Properties and Global Warming Potential of Green Concrete with Wheat Straw Ash and Silica Fume

Cement and concrete are among the major contributors to CO2 emissions in modern society. Researchers have been investigating the possibility of replacing cement with industrial waste in concrete production to reduce its environmental impact. Therefore, the focus of this paper is on the effective use of wheat straw ash (WSA) together with silica fume (SF) as a cement substitute to produce high-performance and sustainable concrete. Different binary and ternary mixes containing WSA and SF were investigated for their mechanical and microstructural properties and global warming potential (GWP). The current results indicated that the binary and ternary mixes containing, respectively, 20% WSA (WSA20) and 33% WSA together with 7% SF (WSA33SF7) exhibited higher strengths than that of control mix and other binary and ternary mixes. The comparative lower apparent porosity and water absorption values of WSA20 and WSA33SF7 among all mixes also validated the findings of their higher strength results. Moreover, SEM–EDS and FTIR analyses has revealed the presence of dense and compact microstructure, which are mostly caused by formation of high-density calcium silicate hydrate (C-S-H) and calcium hydroxide (C-H) phases in both blends. FTIR and TGA analyses also revealed a reduction in the portlandite phase in these mixes, causing densification of microstructures and pores. Additionally, N2 adsorption isotherm analysis demonstrates that the pore structure of these mixes has been densified as evidenced by a reduction in intruded volume and a rise in BET surface area. Furthermore, both mixes had lower CO2-eq intensity per MPa as compared to control, which indicates their significant impact on producing green concretes through their reduced GWPs. Thus, this research shows that WSA alone or its blend with SF can be considered as a source of revenue for the concrete industry for developing high-performance and sustainable concretes