Papers by Keyword: Compressive Behaviour

Abstract: Two approaches can be used to study the size effect: one based on the change in sample size, and the other based on the variation in the aggregates size. The main objective of this research was to study the second approach. We studied 6 various concrete mixes and each test was repeated three times. For each material, uniaxial cyclic compressive tests have been performed to investigate the behaviour of concrete in a partially damaged state. The specimens were submitted to three levels of loading corresponding to 30, 60 and 80% of the maximal compressive strength. The damage indicator chosen is the decrease of Young’s modulus and the tightness indicator is the gas permeability. Results show that the concrete composition and more particularly the aggregate size have an important influence on the mechanical and transfer properties of concretes.

Abstract: In this paper, the effect of polyacrylonitrile (PAN) fibre addition at 0%, 0.1% and 0.2% volume fraction on the compressive behaviour such as compressive strength, residual strength upon heat exposure and compressive stress-strain relationship of lightweight oil palm shell concrete (OPSC) was investigated. OPSC with PAN fibres was found to exhibit reduced strength deterioration upon exposure to elevated temperatures of 100 °C, 200 °C and 400 °C. The strain at peak stress and the compressive ductility of OPSC were also increased with the addition of PAN fibres. Despite the reduced workability, no significant decrease in the compressive strength and saturated density of OPSC was observed in the presence of PAN fibres.

Abstract: The main aim of this work is the mechanical characterization of a composite material resulting from the combination of three by-products coming from industry, namely, flue gas desulfurization (FGD) gypsum, granulated cork and textile fibers from tire recycling. The material is considered as a green material as the raw material are considered by-products and it is intended to be used as a building material for non-structural purposes in civil engineering construction. The mechanical characterization includes uniaxial compressive tests and bending tests for characterization of the fracture behavior. Additionally, ultrasonic pulse velocity is measured to evaluate its variation with time of curing.

Abstract: The mechanical response of single-walled zigzag silicon-germanium nanotubes (SiGeNTs) under tensile and compressive loadings is modeled via atomistic simulation method. The inter-atomic forces are described using the Tersoff's empirical bond-order potential. Initially, the comparative simulations of the bond lengths are presented and quite accurate behavior of the model is demonstrated. Afterwards, the results of the total strain energy are used to establish an expression for evaluating Young's modulus of the nanotubes. Since different choices of wall thickness significantly affect the calculation of Young's modulus, the effective modulus of elasticity is introduced. This procedure provides an accurate means for predicting the elastic modulus of the nanotubes. Numerical simulations were also performed to investigate the buckling behavior of SiGeNTs. Dependence of the critical buckling load on diameter and length of the nanotubes is shown. Finally, the effect of temperature on the axial compressive load of SiGeNTs is also discussed.

Abstract: Foamed aluminum has been recently developed as one of new structure functional materials due mainly to its excellent properties such as energy absorption property. It is significant to investigate the compressive behavior and energy absorption property of foamed aluminum under the condition of static and dynamic loading. The compressive deformation behavior of foamed aluminum with open pore structure was experimentally studied and the effects of the porosity, the type of materials, the pore size and the sample size were discussed in detail by means of the orthogonal experiments. The results showed that the type of materials had the most evident influence on the compressive property of foamed aluminum among the factors investigated, and that the size effects of the experimental results were observed.

Abstract: The steel-plate-masonry composite structure is an innovative type of structural scheme popular in masonry structures with load-bearing walls removed for a large space. A total of 4 column specimens under static loading were tested to mainly study the failure modes, load-carrying capacity, and strain distribution in the critical cross-section. Results show that the composite columns started an initial failure from local buckling of the steel plate located between binding bolts; the main factors influencing load-carrying capacity included thickness of the steel plate, type of injected material, and initial column eccentricity; the working performance of the composite column with epoxy adhesive was better than that with cement grout; and re-distribution of compressive stress existed in the steel plates of the column. Also, the ratio of service load-carrying capacity to ultimate capacity of the steel-plate-masonry composite column is about 70%.

Abstract: In this paper, effect of pre-deformation and ageing on compressive behavior of Ti-58.25wt%Ni was investigated at room temperature. Through range analysis of three factors and three levels on transformation temperature measured by DSC, ageing at 673K enhanced phase transformation temperature obviously, the As temperature could reach 308.02K. Transformations of B2-B19’ and B2-R-B19’ appeared after the treatments. Saw tooth shape phenomenon on the loading curves indicating the typical martensitic transformation was also observed. Dynamic balance due to compatible action among various phase under increased load kept the slope of the loading curves constantly. Pre-deformation by 0.2% resulted in higher compressibility (4.9%), and ageing at 523K caused better recovery (95.4%).

Abstract: In order to effective utilize of recycled fine aggregate concrete (RFAC), it is necessary to clearly understand its behavior and characteristic. In this paper, experimental study on crack behavior of RFAC was conducted with different curing ages. Ratio of its cracking load to ultimate load was analyzed in detail. Experiment shows that this ratio is about 0.8 and is not sensitive to curing age. Comparison to traditional concrete was performed. The result of this paper is helpful to theoretical analysis and practical engineering design of RAC structures.

Abstract: Acoustic emission (AE) is a powerful nondestructive test that can be used to characterize cracking, growth of cracks, and the degree of damage. This technique is clearly distinguished from other nondestructive techniques as it is a nondestructive test that estimates the degree of damage to concrete. In this study, the AE signals emitted during failure, according to the strength of recycled aggregate concrete specimens was examined, in order to characterize them using existing research results and evaluation theories. In addition, it is demonstrated that AE can be utilized to identify crack source and the mechanism of crack growth, which were monitored using a software program developed from the theory of the location of the source of a microcrack.

Abstract: High performance fiber-reinforced cement composites (HPFRCCs) show multiple cracks and a limited damage tolerance capability due to the debonding of the fibers of the cement matrix. For practical applications, it is necessary to investigate the fractural behavior of HPFRCCs to understand the mechanism of the microbehavior of a cement matrix containing reinforcing fibers. We have investigated the acoustic emission (AE) signals in HPFRCCs under monotonic and cyclic uniaxial compressive loads. Four types of specimen were tested. The experimental parameters studied were: the type of fiber (polyethylene or polyvinyl alcohol), the hybrid type (with steel cord), and the loading pattern. The data shows that the progress of the damage in HPFRCCs in the compressive mode is characteristic of the type of hybrid fiber and its volume fraction. From the AE data, the second and third compressive load cycles resulted in a successive decrease in the amplitude compared to the first compressive load cycle. In addition, an AE Kaiser effect was observed in HPFRCCs specimens up to 80% of their ultimate strength. These observations suggest that the AE Kaiser effect has potential for use as a new tool to monitor the loading history of HPFRCCs.