Applied Mechanics and Materials Vols. 253-255

Abstract: Phase change energy storage building material has become a widespread attention for the field of building energy conservation because of its excellent storage properties. The phase change material which is able to adjust the indoor temperature, belongs to the low temperature phase change material. There are lots of kinds of it, and then how to find a suitable phase change material has become a key problem. In this paper, the characteristics of the inorganic material, single organic material, and binary organic material were tested, and the phase change temperature and latent heat of composited phase change material were analysed by differential scanning calorimetry(DSC), which could provide a theoretical basis for the search for the appropriate phase change material.

Abstract: The present paper is part of a research that is developed within the sustainable building design through the revisiting of the traditional construction materials. The results obtained show that the natural stone, enhanced by technological innovations, are often capable of providing excellent performance. Based on the tests, it was possible to verify and validate the hypothesis that the proposed new system of external vertical opaque enclosure consisting in a panel in dry-assembled and pre-compressed blocks of natural stone through reinforcing steel, has good performances when used both in the case of new design in the case of recovery of modern buildings, when the intervention is being addressed within of an overall building improvement regarding the security, sustainability, functionality and image. This paper reports the first results obtained by the study of the feasibility of the envelope being tested, through the definition of all the details of links with the existing building structure.

Abstract: In this investigation, the combined effect of spacing of lateral ties and volume fraction of polyolefin fibres was studied both experimentally and analytically from the point of deformability characteristics of concrete. Low modulus synthetic fibers such as polyolefin based fibers, it is shown that polyolefin fibers with sufficient tensile strength can successfully enhance the mechanical properties of concrete. The mechanism of delaying and arresting the progressive internal cracking from transition zone to the matrix by the fibres can be made use in passive confinement of concrete. Such concrete was termed as polyolefin fiber reinforced concrete (PFRC). In this study the confinement effectiveness of polyolefin fibres of volume fractions 0.3%,0.5%,0.7%,0.9% and 1.2% in addition to lateral ties of spacing 290mm, 145mm and 75mm on concrete prisms of size 150 ×150 ×300 mm were investigated. Such concrete is termed as confined polyolefin fiber reinforced concrete (CPFRC).This paper presents an analytical model(profile) for predicting the constitutive behaviour of CPFRC based on the experimental and analytical results. A total of seventy two prisms of size 150 ×150 ×300 mm were cast and tested under strain control rate of loading. The increase in strength and strain of CPFRC were used in formulating the constitutive relation. The results of the testing demonstrate the behavioral differences between plain and CPFRC and the ability of the synthetic macro fiber to be used as secondary reinforcement in seismic resistance applications.

Abstract: Porous European mixes, PEMs, are porous asphalts which when compacted have an air void content usually in excess of 20%. PEMs points of strength are reduction of splash and spray, mitigation of outdoor noise, optimization of skid resistance at high speeds in wet conditions. Conversely, PEMs have quite low bearing properties, clogging, variation of volumetrics over the time, variation of noise, texture, friction, and permeability performance over the time. Furthermore, at the end of their lifecycle many issues arise: RAP variability, uncertainties on the potential for high percentage recycling, potential for recycling a surface layer back to a surface layer. Based on the abovementioned facts, objectives and scopes were then focused into the analysis of the feasibility of a two-layer porous asphalt (TLPA) by recycling from-PEM RAP, when highly variable rap stockpiles are involved. The following main issues were addressed: mitigating the clogging and its related consequences (acoustic and drainability performance over the time); preserving traditional (bearing properties, skid resistance) and premium (silentness, drainagebility) performance; recycling high percentages of from-PEM RAP. Materials selection was followed by mixtures production. Traditional and advanced tests on RAP and recycled mixes were carried out. RAP variability was examined and a method for facing its consequences was proposed. Mechanical performance was adequate and environmental compatibility was achieved. Functional performance resulted very promising. Results are encouraging about the possibility of achieving a satisfactory level of surface performance. Practical applications and perspectives in rehabilitation, maintenance, and research are outlined.

Abstract: During the technology development of modem concrete, concrete structure crack (especially early-age crack) becomes more and more serious and has been one of main research directions of civil engineering. This paper aims at the seriousness of concrete structure crack and presents one of main cause is that concrete early-age (especially autogenous shrinkage) become large through the experimental study. autogenous shrinkage are mainly belongs to temperature cracks and desiccation cracks. Analyses the affection of ash and water reducing agent on the hydration heat, under the optimum proportion experiment which aims at reducing he hydration heat of cement. The best program are obtained that double mix with 20% fly ash and 1.5% water reducing agent .Design mortar’s early anti-crack experiment, and study crack-resistance and other mechanical properties based on different ages & different mix proportion. From the experiment, analyses early cracking under the influence of admixtures. The mix proportion of 20% fly ash, 10% slag and 1.2% water reducing agent can minimize the creation of cracks.

Abstract: The change of steel mechanical properties is because of steel corrosion seriously. An important factor of evaluating the performance of active steel structure is the degradation of steel mechanics performance. Corroded steel mechanics performance degradation accords with four parameters Weibull distribution through analysis the rapid steel corrosion experiment data. The each Weibull distribution parameters of the degradation of the steel corrosion rate, yield strength and ultimate strength are solved through Matlab programming. Weibull distribution simulation results and experimental data agree well. These models can predict the degradation of steel mechanics performance and can help people to evaluate the corrosion steel structure bearing performance to reinforce the steel structure.

Abstract: An algorithm based on modal strain energy method was proposed to identify the existence, the location and the extent of damage for a functionally graded materials (FGMs) Bernoulli-Euler beam. ABAQUS standard finite element program was used for the dynamic analysis of the FGMs Bernoulli-Euler beam. The damage indicator for the damage identification of the FGMs Bernoulli-Euler beam was developed by way of modal strain energy method. A numerical example was given to demonstrate the effectiveness of the proposed algorithm. Numerical results show that the proposed algorithm is effective in identifying the damage for the FGMs Bernoulli-Euler beam.

Abstract: A assessment method on quality detected system was developed on cylinders inner wall coating through the hydraulic radial expansive load system and acoustic emission testing technology,. Put double probes linear position principle and uniform motion of load system together, and make curved positioning come true based on the technical principle of locating acoustic emission source. The disadvantage was solved that double probes can’t make acoustic emission source planar positioning. The result showed that this system can provide a precise identification and location; it has fast testing velocity and portable device.

Abstract: The computed tomography was introduced to track the development of cracks in cement matrix and interfacial transition zone of MgO concrete under load to failure. Results indicated that some pores were present before concrete was loaded due to none compaction which would tend to initiate cracks expanding. After loading, energy transferring route kept changing and extended towards weak area and it chose to be released through aggregates when concentrated stress on cracks tip surpassed ultimate load with consequences of some cracks getting interconnected with each other through cement matrix. Differentiated and Binarized CT images analysis confirmed that width of cracks was increased and extending routes diversified with loading implemented and interfacial transition zone remained primary choice for cracks development.

Abstract: The aim of this project was to develop of mix design nomograph for PFC that can be used for estimated the required compressive strength and splitting tensile strength with the required PET and water-cement-ratio.The fibers were prepared by using plastic granulator machine SLM 50 FY with size passing 10 mm and retained 5 mm sieve. Different volumes percentages of PET fibers with 0%, 0.5%, 1.0% and 1.5%, were introduced in concrete mixes. The specimens prepared for this study was cylinder concrete with 100 mm diameter and 200 mm height. The laboratory work for physical properties were focused on density and workability, meanwhile for mechanical properties were focused on compressive strength, splitting tensile strength and modulus of elasticity of PET fiber concrete (PFC). The experiment results indicate that the addition of PET fibers significantly decreased the compressive strength and splitting tensile, however the compressive strength still can be acceptable since achieved the mix design The nomograph developed can be used to estimate the desired compressive, splitting tensile strength as well as the modulus of elasticity (MOE).