Journal of Materials and Engineering Structures

15-24

Authors: Anwar Ul-Hamid, Huseyin Saricimen

This study proposes durable concrete mix design suitable for use in superstructures of an industrial plant of a cement company located in an area marked by heavy industrial pollution. Concentration of pollutants in the environment was recorded by undertaking ambient air quality monitoring along with an assessment of corrosivity of soil and ground water present at the site. Type of reinforcement, concreting procedures and protection methods were determined for reinforced concrete that was intended to be used in conjunction with steel structures. Experimental results indicated that soil and groundwater constituted no risk for the substructure. However, air was highly polluted and deemed to be severely corrosive due to the presence of chloride and sulfate salts, SO2 and CO2 in concentrations recorded several times higher than at a comparable industrial area. A concrete mix design suitable for observed conditions was recommended. Additionally, it was suggested that concrete reinforced with black steel bars should be completely coated while that using FBE coated steel bars should be coated up to a height of 1.5m from the grade level for protection against ingress of salt and water.

35-46

Authors: Stephen Adeyemi Alabi, Jeffrey Mahachi

Fires adversely affect the performance of concrete when expose to extreme temperatures. However, it is important to study the effects of elevated temperature on the concrete properties. Concrete often contains other cementitious materials such as ground granulated blast furnace slag (GGBFS) and this has been successfully used to improve its properties. Hence, little or no study has been carried out on the use of ground cupola furnace slag (GCFS) in concreting. Therefore, this paper investigates the behavior of concrete blended with GCFS at elevated temperatures. A total of 300 samples were prepared with four different GCFS contents. The test specimens were cured for 28-d and 56-d and subjected to elevated temperatures ranging from 200oC to 800oC up to 24 h. The slump, residual compressive and tensile strength tests were carried out on fresh and hardened concrete. The results showed that the compressive strength and splitting tensile strengths of concrete generally increased with increasing % GCFS content but decreased as temperature increases. At 28-d and 56-d, the strengths were observed to be maximum at 10% replacement when the temperature is 200oC compared to other mixes. It can be concluded that the strength drastically decreased at temperature above 200oC. An analysis of variance (ANOVA) was also carried out to determine the effect of the elevated temperature and percentage replacement of cement with GCFS on the 28-d and 56-d compressive strength of concrete. The results showed that temperature and % GCFS content had a statistically significant effect on the concrete performance. Based on Tukey’s honestly significant difference (HSD), the effect of GCFS was found to be statistically non-significant for 4% and 6% GCFS content at 28-d; and 2% and 4% GCFS content at 56-d. The effect of temperature was also found to be statistically non-significant for 600oC and 800oC at 28-d; and 27oC and 600oC; 200oC and 400oC at 56-d.

57-72

Authors: Abdulrahman S. Mohammed, Taghreed Kh. Mohammed Ali , Noor A. Rajab, Nahla Hilal

Iraq industrial activities related to huge amounts of solid, non-biodegradable waste, waste low density Polyethylene (LDPE) plastic being among the well-known. So in this study, the scarped LDPE food boxes were transformed into fine particles and used as a sand for cement mortar and concrete. LDPE wastes were utilized to alter 0 to 25% of fine aggregates in mortar mixtures and 0% to 30% in concrete mixes at an increment of 5%. Compressive strength and dry density were tested for all mortar and concrete specimens. In addition, splitting tensile strength and ultrasonic pulse speed were tested for specimens of concrete. Results show that mass, pulse speed of ultrasonic, splitting and compressive tensile strengths were lowered as the size of LDPE raised. The lowest value of dry density, compressive strength and splitting strength was 2240 kg/m3, 18.7 MPa and 1.68 MPa, respectively, for 15% replacement of sand by the LDPE waste in concrete specimens. Whilst, the value of ultrasonic pulse velocity of LDPE concrete mixtures tends to decline lower than the reference values, but it remains nearly to the stander concrete mixtures and can be classified as excellent quality concrete. The density and compressive strength were decreased by using LDPE waste in mortar mixes for all replacement ratios reaching 12% and 42% respectively for 25% substitute.

83-96

Authors: Nitish Raj Bastola, Mena I. Souliman, Ashish Tripathi, Alexander Pearson

Among the various distresses in flexible pavement structures, rutting and fatigue cracking can be accounted as two of the major distresses that need to be addressed by pavement engineers. Laboratory tests, such as four-point bending beam and flow number are utilized to characterize the rutting and cracking resistance of flexible pavements. Various construction practices are introduced to reduce the effect of fatigue and rutting in pavement structures. One of such methods is applying fibers to the asphalt mixture to prolong the serviceability and the performance of the pavement structures. The use of fibers is applicable to freshly constructed pavements as well as in the pavement rehabilitation and maintenance work, such as overlay. This paper primarily analyses the application of fibers in the overlay of pavements. The two major cases of the pavement with original asphalt overlay and the one with fibers mixed asphalt overlay is considered utilizing a developed testing program where the mechanistic analysis as well as the economic effectiveness is evaluated. 3D move analysis software package is utilized extensively as a means of mechanistic analysis tool. It is found that the fiber mixture pavement overlay had a higher pavement life than the ordinary asphalt overlay. In addition, the cost effectiveness in terms of fatigue and rutting of fiber-reinforced overlay structures were 4.4 and 4.1 times the unmodified mixtures, respectively. The use of fibers in the overlay of pavement resulted in higher pavement life with a high cost effectiveness.

113-124

Authors: M. Ouanani, B. Tiliouine, N. Belkheri

In the present article, 3D Finite Element Model (FEM) of a bridge structure under load dynamics is performed in order to assess the sensitivity study of Load-Dependant Ritz vectors (LDR) on modal and seismic responses of cable stayed bridges. In this context, two techniques are examined in the present study for solving structural dynamics problems; the Traditional Modal Superposition (TMS) technique and that of Load-Dependent Ritz orthogonal vectors (LDR). The latter is based on a very efficient algorithm allowing the systematic generation of Load-Dependent Ritz orthogonal vectors (LDR), the accuracy of this method is significantly influenced by the selection of LDR vectors used for the modeling of the structural behavior. The cable-stayed bridge connecting two districts in eastern Algeria, characterized by an expected Peak Ground Acceleration (PGA) equal to 0.275g in accordance with Algerian seismic design code is selected in order to perform critical modal properties such as, frequencies, shapes of the required vibration modes and effective mass participation as well as the dynamic response of the cable stayed bridge under earthquake loadings in three orthogonal directions (longitudinal, transversal and vertical). The results of this study reveal that the LDR vectors method which has the important advantages of short Central Processing Unit (CPU) time as compared to traditional modal method is very efficient for modal and seismic analyses of cable stayed bridges.

141-151

Authors: Mohammed Mekki, Sidi Mohammed Elachachi

The purpose of this article is to contribute to the study of the seismic behavior of structures interacting with the ground and to offer new tools for the treatment of relevant problems, oriented towards the new seismic design philosophy of structures: the design performance-based design. The issue is part of the proposal for simplified models to address a complicated problem such as soil-structure interaction (ISS). The nonlinear behavior of the structure is determined by a capacitive approach based on the seismic performance such as the N2 method proposed by Peter Fajfar. In its original version, this method considers that the structure is fixed at its base, neglecting the ISS. Our contribution will be to make some modifications to this approach to introduce the effect of the soil on the nonlinear response.