Modelling the mechanical properties of concrete produced with polycarbonate waste ash by machine learning.

India's cement industry is the second largest in the world, generating 6.9% of the global cement output. Polycarbonate waste ash is a major problem in India and around the globe. Approximately 370,000 tons of scientific waste are generated annually from fitness care facilities in India. Polycarbonate waste helps reduce the environmental burden associated with disposal and decreases the need for new raw materials. The primary variable in this study is the quantity of polycarbonate waste ash (5, 10, 15, 20 and 25% of the weight of cement), partial replacement of cement, water-cement ratio and aggregates. The mechanical properties, such as compressive strength, split tensile strength and flexural test results, of the mixtures with the polycarbonate waste ash were superior at 7, 14 and 28 days compared to those of the control mix. The water absorption rate is less than that of standard concrete. Compared with those of conventional concrete, polycarbonate waste concrete mixtures undergo minimal weight loss under acid curing conditions. Polycarbonate waste is utilized in the construction industry to reduce pollution and improve the economy. This study further simulated the strength characteristics of concrete made with waste polycarbonate ash using least absolute shrinkage and selection operator regression and decision trees. Cement, polycarbonate waste, slump, water absorption, and the ratio of water to cement were the main components that were considered input variables. The suggested decision tree model was successful with unparalleled predictive accuracy across important metrics. Its outstanding predictive ability for split tensile strength (R2 = 0.879403), flexural strength (R2 = 0.91197), and compressive strength (R2 = 0.853683) confirmed that this method was the preferred choice for these strength predictions.

Effects of Different Orientation Angle, Size, Surface Roughness, and Heat Curing on Mechanical Behavior of 3D Printed Cement Mortar With/Without Glass Fiber in Powder-Based 3DP.

Powder-based (inkjet) three-dimensional printing (3DP) technology presents great promise in the construction industry. The capacity to build complex geometries is one of the most appealing features of the process without formwork. This article focuses on the vital aspect of using a modified powder (CP) instead of commercial powder (ZP 151). It also discusses the effects of the size of specimens and the curing process of 3DP specimens. This article presents not only the improved mechanical properties of the mortar that are revealed through a heat-curing procedure but also the properties of the reinforced mortar with chopped glass fibers. Experiments are conducted on cubic printed mortar specimens and cured in an oven at different temperature regimes. Tests show that 80°C is the optimum heat-curing temperature to attain the highest compressive and flexural strength of the specimens. The orientation angle has a significant effect on the mechanical behavior of printed specimens. Therefore, specimens are prepared by printing at different orientation angles to compare the mechanical properties of common construction materials. Powder-based 3DP has three planes (XY, XZ, and YZ) along which a load can be applied to the specimen. The mechanical strength in each direction across each plane is different, making it an anisotropic material. For CP specimens, the highest compressive strength was obtained using a 0° rotation in the printing orientation of the XY plane. For shear strength, a 45° orientation gave the optimum result, while for tensile and flexural strength, a 0° orientation provided the highest values. The optimum strength for ZP 151 specimens in compression, shear, tension, and bending was obtained by printing with orientation angles of 0°, 30°, 0°, and 0°, respectively. Finally, laser scanning of the printed specimens has been conducted so the surface roughness profiles for the 3DP specimens of ZP 151 and CP can be compared and presented.

A Study into the Effect of Different Nozzles Shapes and Fibre-Reinforcement in 3D Printed Mortar.

Recently, 3D printing has become one of the most popular additive manufacturing technologies. This technology has been utilised to prototype trial and produced components for various applications, such as fashion, food, automotive, medical, and construction. In recent years, automation also has become increasingly prevalent in the construction field. Extrusion printing is the most successful method to print cementitious materials, but it still faces significant challenges, such as pumpability of materials, buildability, consistency in the materials, flowability, and workability. This paper investigates the properties of 3D printed fibre-reinforced cementitious mortar prisms and members in conjunction with automation to achieve the optimum mechanical strength of printed mortar and to obtain suitable flowability and consistent workability for the mixed cementitious mortar during the printing process. This study also considered the necessary trial tests, which are required to check the mechanical properties and behaviour of the proportions of the cementitious mix. Mechanical strength was measured and shown to increase when the samples were printed using fibre-reinforced mortar by means of a caulking gun, compared with the samples that were printed using the same mix delivered by a progressive cavity pump to a 6 degree-of-freedom robot. The flexural strength of the four-printed layer fibre-reinforced mortar was found to be 3.44 ± 0.11 MPa and 5.78 ± 0.02 MPa for the one-layer. Moreover, the mortar with different types of nozzles by means of caulking is printed and compared. Several experimental tests for the fresh state of the mortar were conducted and are discussed.