Applied Mechanics and Materials Vols. 357-360

Abstract: Intelligent material is a kind of multifunctional composite bionic design, can sense environmental conditions, through the sensor network, interest will be provided to the control system, to respond to take action. Self-diagnosis and through self-growth, in situ composite regeneration mechanism of system failure, repair some local damage or destroy; to the changing external environment and conditions, timely adjust its structure and function. Because of its relative to the performance of traditional materials with special excellent, with broad prospects for development.

Abstract: According to GB/T 26743-2011, 37 different surface state of 8 mm CFRP tendons are made on the mechanical properties test to determine some mechanical properties such as tensile strength, elastic modulus and elongation rate. The experiment process, experimental method and failure state are introduced in detail. Considering many factors to the experimental results, the results are analyzed from production process, binder type, anchorage length and fiber species. The results showed that stress-strain curves are straight lines and the failure mechanism has brittle fracture characteristics. From the point of view of detection method, anchor end must adhere sand in accordance with anchorage of resin sleeve in national standard when testing. CFRP tendon of fiber volume ratio 63%-65%, thread depth of which is suggested to be 0.3-0.4mm, is recommended to produce by one molding process. Anchorage length is suggested to be 200mm above.

Abstract: Experimental study was carried out on the concrete mixed with machine-made sand and recycled coarse aggregate (MSRAC), three strength grades of concrete were designed by changing the water to cement ratio as 0.36, 0.45 and 0.55, while the sand ratio varied in a range of 32%~38%, 32%~42% and 38%~44% successively. The workability and the mechanical properties such as compressive and splitting tensile strengths and elastic modulus of MSRAC were tested. The results show that although the mechanical properties of MSRAC were influenced by sand ratio, they were still controlled by the water to cement ratio. The ratio of axial compressive strength to cubic compressive strength and the elastic modulus of MSRAC basically satisfy the specifications of the current design code for concrete structures. It should be noticed that the tensile strength of MSRAC is lower than current specification, and tends to reduce with the increase of water to cement ratio.

Abstract: Anti-penetrability performance test and carbonization test of high performance concrete with high volume fly ash were done and were compared with normal concrete. Test illustrated that filled the concrete dense function of high quality fly ash were superior to common concrete. Average carbonation depth of high quality fly ash concrete was slight inferior to carbonation depth of the common concrete. Keywords: anti-penetrability performance; fly ash; high performance concrete; carbonation

Abstract: A set of new hybrid fiber reinforced high-performance concrete was developed and studied by experiment. The fibers incorporated the concrete are the collection of the steel fiber, modified polypropylene fiber and polypropylene with total fiber content not more than 1%. And the compressive test, splitting tensile test and the flexural toughness test were performed on eight groups of specimens. Based on the load-deflection and load-CMOD curves and the equivalent flexural tensile strength, the effect of fiber volume fraction and hybrid mode upon concrete's mechanical properties and post-peak behavior were investigated. The test results show that the mixing of the three different fibers can increase concrete's splitting tensile strength and flexural toughness more effectively with no significantly effect on compressive strength. The mixture of the three different fibers exist the optimization problem. Based on the results of the analysis, the compatible proportion of the three fibers is 0.7% steel fiber, 0.19% modified polypropylene fiber and 0.11% polypropylene fiber.

Abstract: There existed a competitive adsorption of polycarboxylate (PC) molecular between cement particles and clay particles, and the amount of effective adsorption of PC on the cement particles was decreased. The clay particles carry a negative charge, so the Ca²⁺ that produced by the hydration of cement clinker minerals could be adsorbed. The positive charge density on the surface of cement particles was decreased. The amount of effective adsorption of PC on the cement particle surface was also decreased. The basic reason of the reduction of water-reducing rate of PC was the decreased of the amount of effective adsorption of PC on the cement particle surface.

Abstract: This paper studies the relationship of the main properties of desulphurization gypsum based inorganic thermal insulation mortar. The results show that there are different linear correlations between fresh bulk density, hardened bulk density, compressive strength, volume water absorption, thermal conductivity and dry bulk density that is from 240 kg·m^-3 to 500 kg·m^-3. The linear correlations can provide some useful reference for the research and application of desulphurization gypsum based inorganic thermal insulation mortar.

Abstract: Based on polycarboxylate chemistry, polycarboxylate superplasticizers (PCs) with hydrophobic side chains were synthesized through radical copolymerization reaction. The molecular weight and polydispersity index were analyzed by gel permeation chromatograph (GPC), and the results showed the same structural information. The performances of PCs in cement paste were tested by measuring the fluidity and fluidity retention. The slump and the compressive strengths of concrete were also determined. Additionally, the foaming behavior of PCs was investigated by the foam volume, the surface tension of PCs aqueous solution,and the air content of concrete. According to the data, the hydrophobic side chains of PCs may affect the hydration reaction of cement resulting in better workability.

Abstract: s: The pore structure theories model of free-steaming foamed concrete has been established by observing its pore microstructure and morphology with SEM,and the characteristics of the pore structure has been discussed in this paper . According to the difference among its actual strength and theory strength, associated with observation of the morphology and structure of the hydration production of free-steaming foamed concrete with SEM, the influence of pore structure on the strength has been analyzed in this paper.

Abstract: The sustainability of the construction material is increasingly coming to the forefront of the structure design and maintenance decisions. To address this, development of a new class of more sustainable construction material is needed, especially in China. This paper reports on the development of the green high-performance fiber-reinforced cementitious composites (GHPFRCC) with high volumes of fly ash and PVA fiber, and emphasizes the axial compressive strength and elastic modulus of GHPFRCC. Experimental results show that the prism axial compressive strength of GHPFRCC ranges from 15MPa to 40MPa. The elastic modulus of GHPFRCC is around 16-35GPa, typically lower than concrete.