- Journal Details
- First Published
- 23 May 1993
- Publication timeframe
- 4 times per year
- Open Access
Optimization of the Concrete Delivery and Placement Process Using a Simulation
Page range: 1 - 6
Integrated construction processes are stochastic systems. For these cases a computer simulation is used. This paper presents the design and construction of an integrated construction process, i.e., the production-transportation-consumption of fresh concrete. When creating a model in an Extend v4, modelling techniques and a general knowledge of construction are used. Data obtained from actual processes is used for the model parameters and input variables. The main contribution is a simulation model developed for the process for the optimization and selection of variants. This approach complements the heuristic methods of the assessment of construction processes and exact methods, where the decisive body will have the values of the individual decision-making criteria.
- Integrated construction process
- computer simulation
- fresh concrete
- Open Access
Reactivity of Granulated Blast Furnace Slag
Page range: 7 - 14
The Algerian iron and steel complex of El Hadjar, near the city of Annaba, produces a granulated blast furnace slag (GBFS) mainly used by the local cement factories as an addition to clinker of up to 30 % as maximum content, for manufacturing a compound CEM II type cement (Algerian Standard).
With the aim, on the one hand, of limiting the use of high clinker content in Algerian cement plants and replacing it with other constituents such as granulated blast furnace slag and, on the other hand, to use this slag as an addition to local concrete, we have attempted to characterize it according to its degree of reactivity.
The use of chemical activity indexes and caustic soda tests lead to disappointing results that are contradicted by the results obtained on mortar within the scope of the standard determination of a hydraulic efficient index. The results obtained indicated that the classification of El Hadjer slag strongly depends on its degree of fineness; it also has weak short-term activity, denoting a slower kinetics of reaction compared to classical slag. These results permit us to recommend a minimal Blaine of 3500 cm2/g for this slag.
A more intensive use of this slag in cement and concrete is undoubtedly possible, but this must be demonstrated by conducting tests on mortar and validating by a study on concrete.
- Granulated slag
- activity indexes
- Open Access
Comparison of Pavement Layers Responses with Considering Different Models for Asphalt Concrete Viscoelastic Properties
Page range: 15 - 20
In this paper, a comparison between pavement responses is performed by considering two different models for the linear viscoelastic behavior of an asphalt concrete layer. Two models, the Maxwell model and the Kelvin-Voigt model, are generalized. The former is used in ABAQUS and the latter in KENLAYER. As a preliminary step, an appropriate structural model for a flexible pavement structure is developed in ABAQUS by considering linear elastic behavior for all the layers. According to this model, when the depth of a structural model is equal to 6 meters, there is a good agreement between the ABAQUS and KENLAYER results. In this model, the thickness of the pavement is equal to 30 centimeters, and the thickness of the subgrade is equal to 5.7 meters. Then, the viscoelastic behavior is considered for the asphalt concrete layer, and the results from KENLAYER and ABAQUS are compared with each other. The results indicate that the type of viscoelastic model applied to an asphalt concrete layer has a significant effect on the prediction of pavement responses and, logically, the predicted performance of a pavement.
- Flexible pavements
- Open Access
Impact of Biocorrosion on the Durability of Etics and Empirical Findings About the Periodocity of Maintenance
Page range: 21 - 28
Generally, the role of living organisms (especially bacteria, cyanophytes, algae and fungi) in the physical and chemical processes of the biocorrosion of an external thermal insulation composite system (ETICS) is underestimated. These organisms are the ones that are responsible for a wide range of changes in or "diseases" of building materials and constructions, including damage to a building´s appearance or the destruction and complete collapse of the characteristics and requirements of materials and the ETICS construction.
The following article concerns the impact of biological factors on the durability of ETICS. It shows the importance of and necessity to maintain it, and the method and periodicity of the maintenance.
- external thermal insulation composite system (ETICS)
- biocorrosion facades
- crustation of building material
- ETICS life cycle
- Open Access
Extensive Testing and Comparison of a New Type of Target for Use in Engineering Surveying
Page range: 29 - 40
The paper deals with the testing of a special target for determining the exact dimensions of steel structures and their descriptions. In most cases, the accuracy required in mechanical engineering is on the order of millimetres, and the location of a point on a steel construction is marked by a centre punch. Due to the segmentation of steel constructions and the impossibility of the vertical placement of a target, it is very difficult to use ordinary prisms because of their size and the linear error from a wrong rotation and a nontrivial conversion of the centre of a prism into a centre punch on a steel construction. For a more accurate determination of spatial coordinates, a special reflective target with a reflective foil and a mechanical collimator, which ensures the correct angle to the target device according to the instructions of the person at the instrument, has been developed. Centration with a high degree of accuracy is achieved by a spike. Its functionality and usability goals have been tested and compared with standard methods of measurements and goals in engineering structures.
- Reflective target
- measurement of steel constructions
- engineering surveying