Prefabricated construction is a state-of-the-art construction technology of both socio-economic and environmental benefits, but sometimes, it is not welcome due to its high cost. Governments play an important role in deeply promoting prefabricated construction, but its effects are not clear. This paper developed a system dynamics model for investigating and simulating the impacts of government incentive strategies on prefabricated construction by considering the evolutionary game process between the government and contractors. Data of Shanghai, China, is collected for demonstration and validation of the developed simulation model. Results show that (1) the evolutionary stable strategy does not exist in static game process; (2) the rate of adopting prefabricated construction is affected by the level of penalties and subsidies; (3) dynamic incentive strategies can better improve the stability of the evolutionary game process; and (4) the rational range of incentive rate can be obtained. Findings of this study facilitate governments to formulate and improve the incentive strategies of prefabricated construction, thus boosting the development of construction industrialization.
Biomass energy, contributing to about 80% of the total energy supply, is considered an important energy source in Madagascar. Although around 80% of energy use comes from biomass energy, the current application method of biomass in Madagascar is still in the earliest stage, which is not safe and sustainable. This is because the main form of biomass energy used in Madagascar is still solid charcoal and wood, and the technology is limited. Thus, it is necessary to search for better ways to utilize biomass energy in Madagascar because of high prices of traditional energy carriers and massive environmental pollution. This paper reviews the following: (1) a variety of available biomass wastes for energy in Madagascar including farming residuals, animal wastes, and forest wastes, as well as urban and industrial organic wastes; (2) advanced technologies, such as gasification, torrefaction, and fermentation, that can convert these wastes to biomass energy in forms with higher energy efficiency such as biogas, biocoal briquette, and ethanol fuel, which can not only help to achieve resource utilization of wastes and circular economy but also ease the energy crisis faced by Madagascar; and (3) Madagascar focused on the development of biomass energy with strategic policies and programs. International assistance also contributes to future promotion of biomass energy. It identifies several areas where research is urgently required to adopt instrumental policies to ensure that both rural development objectives and renewable energy targets are met with financial support from the government and international assistance.
This study aimed to research the whole stress–strain curves of coral Fly Ash-Slag Alkali-Activated Concrete (CAAC) in different strength grades. Fly ash-slag alkali-activated concrete was used as cementing materials to produce coral aggregate concrete. A monotonic loading test was conducted on the prismatic specimens to obtain elastic modulus (Ec), Poisson’s ratio (μ) and the constitutive relationship of CAAC under uniaxial compression. When the strain of CAAC reached the maximum value, the specimen was split and damaged rapidly. As the strength grade increased, the ratio of residual stress (σri) to peak stress (σ0i) decreased in the range of 0.17–0.28. The Ec of CAAC increased gradually, and μ increased to the peak value and then decreased. According to the test results, the constitutive equation of CAAC can be expressed by piecewise expression, which can better reflect all the experimental characteristics. It was also found that CAAC has many similar characteristics with coral concrete and lightweight aggregate concrete. To improve the strength and toughness of CAAC, some fibers, such as organic fiber, can be added to expand the application of CAAC in engineering projects.
This paper focused on the optimization of the C40 fly ash concrete pavement, which was considered as a measure to accelerate the consumption of industrial solid wastes such as fly ash, committing to the goal of zero waste. By comparing with three groups of ordinary mix proportion, the performances (e.g., mechanical properties, durability, and brittle property) of the optimized mix proportion were evaluated via multiple mechanical and physical tests. Their air voids’ structure was characterized by the BJH method (a method to calculate pore size described by Barrett, Joyner, and Halenda), and the results were combined with the road performances of concrete to analyze the formation mechanism of high durability of optimized fly ash pavement concrete. As for the experimental results for the optimized, its 28 d compressive strength peaked at 50.8 MPa together with corresponding 28 d flexural strength at 8.2 MPa, which indicated a favorable mechanical performance for wide application in pavement construction. Except for the mechanical properties, the better durability indicators obtained after optimization also provided a more compact pore structure for the optimized. The raw materials and construction technology of the two kinds of pavements were compared. Promoting the use of optimized fly ash pavement concrete can break the situation of the asphalt pavement monopolizing heavy-haul highway and greatly reduce the industrial wastes which can be used as raw materials in the production of cement, such as blast furnace slag and fly ash. It was proved that the optimized fly ash concrete pavement can be used to replace the asphalt pavement under the premise of achieving the same working performances.
The rebar sleeve grouting connector is an important vertical connection component in the fabricated structure. This paper focuses on the study of the mechanical performance of the reinforcement sleeve grouting connector under unidirectional loading and high-stress cyclic loading. Through experimental analysis, the researcher studied the mechanical properties and anchoring mechanism of a total of 54 rebar sleeve grouting connectors with 2 test methods, 9 sizes, and 3 defect types under unidirectional loading and high-stress cyclic loading. The test results show that there occurred two types of failure, namely, rebar fracture and bond-slip. To be more specific, the specimens with anchorage lengths of 8.0 d and 7.0 d both encountered the result of rebar fracture, which meets the relevant regulations on the strength and deformation of the joints of the level-I connection in Technical Specification for Mechanical Connection of Steel Bars (JGJ 107-2010); and the test pieces with the anchorage length of the steel bar of 6.0 d all had the steel bond-slip failure, which does not meet the requirements of the specification.
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