Research on six-pile caps mainly focused on reinforced concrete six-pile caps and steel fiber reinforced ordinary strength concrete six-pile caps. In order to study the force mechanism of steel fiber reinforced high strength concrete (SFRHSC) six-pile caps, eight SFRHSC six-pile caps with the plane dimensions of 960 mm & times; 600 mm were subjected to static load test. The experimental variables include the volume fraction of steel fiber (0 %, 0.5 %, 1.0 %, 1.5 %), concrete strength grade (C40, C60), effective thickness of pile caps (160 mm, 210 mm, 260 mm) and reinforcement layout (uniform grid, bunched). The tests were carried out to measure and analyze the crack development and failure mode, the load-deflection curve, the concrete strain and steel strain of specimens. On this basis, finite element analysis was conducted by ABAQUS and compared with the experiments. The results show that the failure mode of SFRHSC six-pile caps is the punching failure, and the load-transferring mechanism of six-pile caps conforms to strut-and-tie model. With the increase of the effective thickness of pile caps, the bearing capacity of specimens can significantly increase, and the fiber volume fraction of about 1 % has the best effect on enhancing the bearing capacity of SFRHSC pile caps. Finally, the calculation method for the punching shear capacity of SFRHSC six-pile caps based on strut-and-tie model was proposed.
To procure environmentally - friendly and sustainable super-absorbent polymers (SAP), a concurrent irradiation approach utilizing 60Co gamma-rays is employed to graft acrylic acid (AA) and acrylamide (AM) onto mung bean straw cellulose (MBS-cellulose). Using different solvents to dissolve the straw yielded a more soluble form. The structural characteristics and thermal stability of MBS-cellulose and the graft copolymer are also comprehensively analyzed. The influence of the MBS pre-treatment method, irradiation dose, irradiation rate, cross-linking agent dosage, monomer ratio, and MBS-cellulose proportion on the water absorption capacity and salt resistance of the graft copolymer is investigated. The research indicates that under specific synthesis conditions, the optimal reaction conditions for graft copolymerization were determined via single-factor experiments. The monomer ratio, specifically m (AA):m (Am), was set at 1.4. The material ratio, defined as m (AA + AM):m (MBS-cellulose), was 11. The neutralization degree of the monomer approximated 90 %. The irradiation dose was 6 kGy, the dose rate was 1.4 kGy/h, and the cross-linker dosage was 2.4 %. The resultant MBS-cellulose grafted copolymer exhibited a water absorption capacity of 2,340 g/g and a brine absorption capacity of 211 g/g.
This study evaluated the effects of thermal activation and replacement ratio of waste brick powder (WBP) on the physicochemical characteristics and engineering performance of mortar to recycle waste bricks generated from construction waste as a cement replacement material. Thermogravimetric analysis and X-ray diffraction were performed to analyze the thermal and mineralogical properties of WBP. The flow, compressive and flexural strengths, and water absorption were measured for mortar with WBP thermally activated at 600 degrees C and 800 degrees C with replacement ratios of 6 %, 13 %, and 20 %. The results showed that WBP exhibited thermally stable behavior up to 900 degrees C, with limited mineralogical phase changes observed after heat treatment. For mechanical properties of WBP-based mortar, thermal activation did not have a consistent effect on improving compressive or flexural strength, suggesting that additional thermal activation is inefficient for waste bricks that have already been calcined at high temperatures. In contrast, under low replacement ratio, regardless of thermal activation, WBP-based mortars satisfied most of the compressive strength requirements specified by current industrial standards, confirming the practical applicability of WBP as a cementitious material.
Marble processing facilities produce significant quantities of marble waste, and the disposal of this waste presents economic and environmental challenges. Recent years have seen research focused on composite materials, especially those applicable as building materials, to tackle this issue. This study developed polyurethane (PUR) composite samples incorporating varying proportions of waste marble dust (WMD) for acoustic insulation applications. Composite samples were generated with volume filler ratios between 10 % and 30 % and evaluated against a pure PUR reference. The acoustic properties, including sound absorption and Sound Transmission Loss (STL), were evaluated across low and high-frequency ranges utilising impedance tube methods in compliance with ISO and ASTM standards. Experimental data indicates a direct correlation between increased WMD loading and a marked enhancement in the acoustic damping characteristics of the matrix. The composite with 30 % WMD demonstrated superior performance, especially in the high-frequency range. This research concludes that WMD-reinforced PUR composites provide a cost-efficient and sustainable solution for noise insulation in the construction industry.
The reduction in factor of safety (FOS) of any slope is due to a reduction in total stress. To increase the strength of the soil slope, commonly adopted techniques lead to environmental impact. To overcome this situation, an inert material like Polyurethane (PU) can be mixed in the soil medium to increase the stability of the slope. The present study aims to use PU to stabilise the topsoil of the slope, which effectively increases the FOS. Direct shear tests were performed to understand changes in the shear strength parameters with the addition of various percentages of PU. FOS of slope is understood using Plaxis-2D. Results of the Direct shear tests showed the improvement of cohesion from 15 kPa of virgin soil to around 138 kPa and angle of shearing resistance from 17 degrees to around 58 degrees with the addition of 10 % PU to the soil, with just 7 h of curing. Plaxis-2D analysis indicates the increase in FOS by 22 % with stabilisation of topsoil up to 0.3 m. The study recommends the use of PU to stabilise embankments, as it provides a rapid increase in strength and quick enhancement of slope stability.
