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I show that the equilibrium distribution of matches associated with the empirical transferable utility one-to-one matching (TUM) model introduced by Choo and Siow (2006a, 2006b) corresponds to the fixed point of system of K + L nonlinear equations; with K and L respectively equal to the number of discrete types of women and men. I use this representation to derive new comparative static results, showing how the match distribution varies with match surplus and the marginal distributions of agent types.

This study aims at designing consistent and durable concrete by making use of waste materials. An investigation has been carried out to evaluate the performance of conventional and optimal concrete (including 5% GP) at high temperatures for different exposure times.

An experimental work is carried out to compare the conventional and optimal concrete with respect to weight loss, mechanical strength characteristics (compressive, tensile and flexural) after exposed to 100, 200 and 300 °C with 1, 2 and 3 h duration of exposure followed by cooling in furnace for 24 h and then air cooling.

The workability of granite powder modified concrete decreases as percentage of replacement increases. Compressive, tensile and flexural strengths all increased at 100 °C when compared to strength characteristics at normal temperature, regardless of the exposure conditions, and there was no weight loss noticed. For 200 and 300 °C, the strengths were decreased compared to normal temperature and an elevated temperature of 100 °C, as weight loss of concrete specimens are observed to be decreased at these temperatures. So, the optimum elevated temperature can be concluded as 100 °C.

Incorporating pozzolanic binder (granite powder) as cement replacement subjecting to elevated temperatures in an electric furnace is the research gap in this area. Many of the works were carried out replacing GP for fine aggregate at normal temperatures and not at elevated temperatures.

Establishing toughness performance in concrete using steel fibres is well understood, and design guides are available to assist with this process. What is less readily understood is the use of Type 2 synthetic fibres to provide toughness. This problem is exacerbated by the wide range of synthetic fibres available, with each different fibre providing different structural properties. This paper seeks to address this issue.

The paper examines the relative pull‐out values of two single fibre types, i.e. steel and Type 2 synthetic fibres. The pull‐out test results have informed the doses of fibre additions to beams which have been used to equate near equal toughness performance for each fibre type.

The results show that synthetic Type 2 fibres, when used at a prescribed additional volume, can provide toughness equal to steel fibre concrete.

The scientific study of fibre pull‐out behaviour is well understood and described herein under additional reading. Practical testing to show contractors and clients how to balance the dose of fibres in concrete, so that synthetic fibres could be used as a steel fibre replacement, is not well researched. This paper bridges the information gap.

Self‐compacting concrete (SCC) offers several economic and technical benefits; the use of steel fibers extends its possibilities. Steel fibers bridge cracks, retard their propagation, and improve several characteristics and properties of the SCC. The purpose of this paper is to investigate the effects of type and volume fraction of steel fiber on the compressive strength, split tensile strength, flexural strength and modulus of elasticity of steel fiber reinforced self‐compacting concrete (SFRSCC).

For this purpose, Micro wire and Wave type steel fibers with l/d ratios of 50 were used. Three different fiber volumes were added to concrete mixes at 0.5, 0.75 and 1 per cent by volume of SCC. Six different SFRSCC mixes were prepared. After 28 days of curing, compressive, split and flexural strength and modulus of elasticity were determined.

It was found that, inclusion of steel fibers significantly affect the split tensile and flexural strength of SCC accordance with type and v_f. Besides, mathematical expressions were developed to estimate the flexural, modulus of elasticity and split tensile strength of SFRSCCs regarding of compressive strength.

It was found that inclusion of steel fibers significantly affected the split tensile and flexural strength of SCC accordance with type and f v.

OWING to vibration troubles which occasionally arise in engine crankshaft propeller systems, it has become necessary to investigate such possibilities in the design stage. In this paper we are concerned with the torsional vibration of an engine crankshaft coupled with flexural vibration of the propeller. The engine crankshaft will have a number of throws, which it has become customary to replace by “equivalent” pulleys which have the same moments of inertia as the complete crankthrows and are usually designated as engine “masses”. Assuming that there is a node in the propeller shaft, we may represent the torsional stiffness of the propeller shaft between the gears and the node by ca / (l−γ) where ca is the torsional stiffness of the propeller shaft; the torsional stiffness of the other portion of the propeller shaft will then be ca/γ. The frequencies of torsional vibrations of the engine crankshaft system about the assumed node are found for various values of γ. The corresponding frequencies of flexural vibrations of the propeller arc also found for the same values of γ. The two sets of frequencies may then be plotted against γ, giving engine crankshaft and propeller frequency curves respectively.

The purpose of this study was to reuse cement kiln dust (CKD) in cement products and report the results of determining the long-term compression and flexural tensile strengths of mortars containing CKD as a partial replacement of sulfate-resistant cement (SRC). During the manufacturing of Portland cement, voluminous quantities of the byproduct dust are produced, which is commonly known as CKD. In the past decade, according to environmental requirements, many researchers have attempted to reuse CKD in cement products.

The long-term compression and flexural tensile strengths of mortars containing CKD as a partial replacement of SRC were tested. The replacement ratios in this study were 0, 5, 10, 15 and 20 per cent. The specimens were exposed to a highly saline environment after normal curing in water for a 28-day period.

The results indicated a slight increase in the strength of CKD–SRC mortar containing 10 per cent CKD and moderate sulfate resistance when the CKD ratio reached 20 per cent, as compared to the reference mortar. In addition, CKD did not adversely affect the properties of SRC mortar subjected to sulfate exposure, even after one year.

The tests were inducted for the first time on SRC, and the new results can be used to produce an environmental-friendly concrete.

This paper aims to qualify traditional concrete mixtures for large-scale material extrusion in an automated, additive manufacturing process or additive construction.

A robust and viable automated additive construction process must be developed that has the capability to construct full-scale, habitable structures using materials that are readily available near the location of the construction site. Accordingly, the applicability of conventional concrete mixtures for large-scale material extrusion in an additive construction process was investigated. A qualitative test was proposed in which concrete mixtures were forced through a modified clay extruder and evaluated on performance and potential to be suitable for nozzle extrusion typical of additive construction, or 3D printing with concrete. The concrete mixtures were further subjected to the standard drop table test for flow, and the results for the two tests were compared. Finally, the concrete mixtures were tested for setting time, compressive strength and flexural strength as final indicators for usefulness in large-scale construction.

Conventional concrete mixtures, typically with a high percentage of coarse aggregate, were found to be unsuitable for additive construction application due to clogging in the extruder. However, reducing the amount of coarse aggregate provided concrete mixtures that were promising for additive construction while still using materials that are generally available worldwide.

Much of the work performed in additive manufacturing processes on a construction scale using concrete focuses on unconventional concrete mixtures using synthetic aggregates or no coarse aggregate at all. This paper shows that a concrete mixture using conventional materials can be suitable for material extrusion in additive construction. The use of conventional materials will reduce costs and allow for additive construction to be used worldwide.

This paper aims to produce lightweight concrete by combining aerated concrete with expanded polystyrene beads concrete to create structural aerated-polystyrene lightweight concrete that satisfies the criteria of sustainability for thermal and sound insulation properties and the structural criteria of having satisfactory compressive strength for structural elements.

The experimental study was carried out to reach the largest compressive strength while maintaining the lowest possible density by preparing nine mixes of concrete, involving different ratios of aluminum waste powder and polystyrene beads as 0%, 0.2% and 0.3% and 0%, 0.1% and 0.2%, respectively, by weight of cement to produce the lightweight concrete with different densities. The performance of mechanical properties, thermal conductivity, ultrasonic pulse velocity, density, modulus of elasticity, acoustic impedance and scanning electron microscopy were studied and discussed.

Results showed that aerated-expended polystyrene beads concrete had the most suitable properties when the proportions of aluminum waste powder and expanded polystyrene beads were 0.2% and 0.1%, respectively. The compressive strength, density, thermal conductivity and acoustic impedance were 38.5 MPa, 1,768 Kg/m³, 0.358 W/(m.k) and 4.91 Kg/m² s, respectively.

The experimental work was done using aluminum scrap waste powder as an expanding agent to produce aerated concrete and combining it with expanded polystyrene bead concrete to produce structural aerated-polystyrene concrete, which contains fine materials (silica fume and local natural raw limestone) and superplasticizers.