Advanced Materials Research Vols. 163-167

Abstract: The segregation of gradation is believed to be one of the main causes of the premature pavement deteriorations. Much of unqualified aggregates used in asphalt pavement construction result in the segregation of gradation. The traditional aggregate handling method has the defects of poor quality in processing and low rate of qualified aggregate in result in highway construction in china. The beginning of the study is from more than 30 sections of the asphalt pavement construction, in which the sieve sizes for aggregate processing and the variation of aggregate gradation is under investigation. Found and used a set of standardized screens for aggregate processing on a large scale processing. The key of the gradation segregation control in asphalt pavement construction is the quality control of the aggregate processing, is pointed out. The relationship between the sieve sizes for aggregate handling and the standard sieve sizes which should be controlled; the relationship between the aggregate specifications and the screens for aggregate processing; and the relationship between the sort of mix and the aggregate specifications, is put forward. With application of the new aggregate processing method, almost all variation factor percent passing key controlled sieves is smaller than 2.6%. The mean surface texture depth measured from 229 inspection sites is 1.03 mm and the maximum variation factor of the texture depth is only 2.7%. The authors believe that the standardized aggregate processing technique reported in this paper is the most effective means to reduce asphalt pavement segregation and may open a new era in the realm of aggregate processing for highway constructions in China.

Abstract: Construction industry in Malaysia is growing rapidly with high demand due to vast development and urbanization. Therefore, many commercial and residential buildings are being developed. The increasing number of construction projects in Malaysia will indirectly contribute to the increase of construction waste generation. Thus, waste minimization is an important area of concern in the implementation of the construction waste management in the construction industry of Malaysia. Data collection and observations was conducted at three construction sites which adopt different type of method with different type of building and size of project in Klang Valley. The calculation of the construction waste index generated at these sites is adopted from Poon et al., (2001). Result showed that construction method, size of projects (GFA), type of building, storage method system, human error and technical problem can affect the amount of waste index (debris) and amount of wastage level generated at construction sites. Therefore waste index and wastage level can be used as operational an indicator for waste minimization of the construction activities.

Abstract: The relationships between NH₄H₂PO₄ content and properties including apparent porosity, bulk density, compressive strength, setting expansion and thermal expansion of the mullite-based investment materials have been investigated. The results show that: With increment of NH₄H₂PO₄ content, the bulk density decreases and the apparent porosity increases for the specimens. When the NH4H2PO4 content is less than 9 mass%, the compressive strength of the specimens clearly decreases with increment of NH₄H₂PO₄ content, and the compressive strength of the specimens heated at 900°C is less than that of the specimens heated at 110°C slightly. With increment of NH₄H₂PO₄ content, the setting expansion obviously increases and the thermal expansion decreases a little.

Abstract: The pile work on the complex properties of three-dimensional finite element analysis has been made by building-up one 4x4 soft pole. Having studied on the factors which affect the flexibility pole compound foundation settlement factor in foundation, include the level of vertical load, elastic modulus of the pile, cushion thickness and elastic modulus. The results show that: the impact of soft pile settlement of the factors, the level of vertical load and pile elastic modulus greater impact cushion modulus of elasticity and thickness of the less affected. As for the pole body elasticity modulus and the bed course elasticity modulus, the compound foundation existence is controlled give value preferential treatment most subsides, the bed courses among them almost can be ignored since effect is less.

Abstract: A method is proposed for the calculation the earth pressure exerted on the inner wall of a special double-row support structure. The analysis shows that there is a pressure gradient between the walls and an amplification coefficient is introduced to reflect the increase of the earth pressure. The predicted and observed behaviors are compared to examine the feasibility of this method and the result shows that this method gives the closest prediction of the deflection of the inner wall.

Abstract: This paper involves a destructive full-scale load test on long bored pile instrumented with strain gauges along the shaft. The load-displacement response, the distribution of axial force, and the thresholds of displacement for fully mobilizing the skin resistances in different soils in tension case were discussed in this paper. The field test results show that the measured tip resistance in the pile under tension is near zero during the whole loading, and the softening is accompanied with a reduction in skin friction when the skin friction is fully developed. It also can be investigated that the threshold of displacement for fully mobilizing skin friction is different even if in the same soil type due to different soil stress states. Generally speaking, the thresholds of relative pile-soil displacement for fully mobilizing skin frictions in the sandy silt, silty sand mixed silt, silty clay, silty clay mixed sand and gravel are about 4 mm, 11 mm, 7 mm, 6 mm, and 5.5 mm, respectively.

Abstract: The comprehensive development in Saudi Arabia forced the private sector to bring foreign employees to assist in accomplishing this development. The number of foreign employees reached to six million people according to the late statistics. This huge number of people exerted pressure on the public free medical facilities that forced the government to issue a decree that instructs private sector to use private medical facilities for their foreign employees. The private sector dealt with this decree in different ways according to the perception of the company from providing full medical coverage for their employees to providing nothing. This has created a problem to many foreigners in which they have to pay for their medical needs. The government, then, issued a new decree that is the mandatory medical insurance. This decree requires the private sector to provide full medical coverage for their foreign employees. This decree will have an impact on the construction companies (contractors) and the cost of the construction projects. This paper presents results of a study conducted to identify the impact of the mandatory medical insurance on the construction contractors in Saudi Arabia. The methodology used was to prepare a questionnaire that investigates the objectives of this study and distributes it to the contractors. The questionnaire includes many aspects among them the impact of this decree on the company performance and the competition between contractors; how this extra expense being dealt with; and the impact on the employee. The questionnaires were distributed to 150 construction contractors and 90 questionnaires were collected. Results of the study reveal the impact of the mandatory medical insurance on the construction contractors in general and according to their classifications. In addition, the study presents the current practice implemented by contractors to provide medical care for their foreign employees.

Abstract: In this paper, in order to get the mechanical properties of the different ratio similar material models and resolve the matching problem of pressure sensor and measured similar material, according to the similarity theories, the repeated loading tests on different ratio similar models were performed by multi-stage loading. This paper got the stress-pressure curve and the failure strength of each model. Test results show that there are significant differences in the matching abilities between different ratio similar materials and pressure sensors, and the matching abilities between different models of the same ratio and pressure sensors also have some differences. The matching ability between similar material and pressure sensor should be detected, so as to correct the experimental data. Test results also show that different ratio similar materials have stable and different mechanical properties. The mechanical properties of the similar material can be adjusted appropriately by changing the ratio. The mechanical properties of different ratio similar materials should be tested before the similar material simulation test.

Abstract: This paper presents the theoretical and experimental results of concrete-filled steel tube columns subjected to axially compression. A total of 6 specimens with outer square sections reinforced by inner cicular steel tube were constructed for experimental investigation. The ultimate strengths of the columns from tests were obtained. The theoretical strengths of the columns were also investigated based on unified strength theory, and compared with the test results. Good agreement can be observed from the comparison.

Abstract: Referancing to the connection characteristic and mechanical behavior as well as the defects in application of joints on concrete-filled steel tube between columns and beams, a new connection type of steel beam throughout joints model is proposed. The inner force transfer mechanism and stress distribution situation of the joint under the monotonous load and hysteretic behavior, ductility, energy dissipation under cyclically lateral load are analyzed using the software ANSYS. The result indicated that the stress of steel pipe is reduced effectively when continious web plate joint is used. Meanwhile, the rigidity of the joint is enhancedand. It is also accord with the seismic design concepts, that is “strong column-weak beam“. During this process of the jiont working, plastic hinge occurs out of joint area on the beam. The hysteretic curves of all the specimens are of a plump shuttle shape .The curves don’t show strength deterioration and stiffness degradation obviously. All these show that this type of joint is effective.