In recent years, geopolymer concrete (GC) has become more popular in construction because of its multiple benefits, such as eco-friendliness, high temperature resistance and resistance to chemical attack in harsh environments. However, GC has limited deformation capability and tensile strength compared to ordinary concrete. Geopolymer fibrous concrete (GFC) exhibits high mechanical properties, such as compressive strength and impact strength. This study aimed to develop a novel composite comprising GFC at the tension zone and GC at the compression zone, and vice versa, are these composites were examined. The impact resistance of two-layered GC-GFC with various ratios (25–75, 50–50, 75–25%) was examined. In addition, a single layer specimen comprising GC and GFC was fabricated and tested as the reference specimen. Twenty-nine mixtures were developed and divided into four series. Four different types of fibre were used in this study; short polypropylene fibre, long polypropylene fibre, short steel fibre and long steel fibre. The ACI committee 544 drop weight test was used to evaluate the impact strength of specimens. Results indicated that the impact strength of GFC was significantly improved in long steel fibre-based specimens. In addition, two-layered specimens comprising different fibres—short polypropylene, long polypropylene, short steel and long steel—exhibited a positive influence on impact strength. Compared to a single-layer specimen, inferior impact strength was recorded in the two-layered specimen.

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SUMMARY :Keeping the quality of mango fruits is a varietal character; it depends to a great extent on the harvesting techniques. The field performance of an Indian Institute of Horticultural Research (IIHR) harvester, a local harvester, tree shaking and hand picking with and without pedicel were compared for cultivars Alphonso and Totapuri mangoes. In case of Alphonso an average man could harvest 428, 400, 232, 285 and 329 fruits per hour from 3-5m high trees using above harvesting techniques, respectively. While for Totapuri, the corresponding values were 385, 344, 178, 92 and 170 fruits per hour the pedicel length of both Alphonso and Totapuri mangoes harvested were 1.27, 0.31, 0.41, 0.95 and 0.00 cm. The average shelf-life was 11.6, 9.0, 5.66, 12.0 and 10.5 days in case of Alphonso and 13.3, 11.0, 7.0, 14.0 and 12 days in Totapuri. IIHR harvester was found to be more feasible and may easily be popularized amongst the mango growers. The presence of pedicel could control the sap oozing and lateral infection while increasing the shelf-life and reducing the damage (6.4%) to the fruits. The operating cost of harvesting was reduced (Rs. 85/tonne for Alphonso and Rs. 75/tonne for Totapuri) as compared to other harvesting techniques. The cost of IIHR harvester is about Rs. 50.

The unsustainable use of resources and the rising demand for traditional concrete have disrupted ecological equilibrium, necessitating the adoption of a more appropriate and long-lasting alternative. One such substitute for cement in concrete production is geopolymer concrete, although this material is prone to cracking and fracturing due to its low tensile strength, leading to costly repairs or even structural collapse. Fiber-reinforced concrete has recently been widely adopted as a construction material to counteract these issues. This research examined the crack proliferation and fracture toughness of geopolymer concrete comprising different fibers using a cracked Brazilian disc. Four different fibers were used, such as polypropylene and steel fiber (short and long), at a dosage of 1.5% by volume. Fracture toughness was computed for various modes (I, II, and I/II) of fractures, and crack propagation from cracked specimens was studied. A different angle of inclination (0, 15, 28, 83, 60, 75, and 90 degrees) was used to conduct the Brazilian disc test on the specimens with respect to the preexisting crack direction. The findings indicate that the increasing loading angle increased the load-carrying capacity. The fracture toughness values of specimens under all three modes ranged from 0.26 to 1.75 MPa.m1/2. Additionally, long polypropylene and steel fibers exhibit higher fracture toughness than short fibers.