Applied Mechanics and Materials Vols. 584-586

Abstract: In the past decade, molecular sieves are applied to the flame retardant research areas. This article introduces the types and functional features of molecular sieve, especially the properties of mesoporous molecular sieve, the function of porous channel system, the method of controlling the aperture and the way of functional modification. On the basis of induction and analysis of molecular sieve in fire-retardant research, I have made three points: (1) Molecular is a good kind of fire-retardant synergist; (2) A little molecular added is enable to improve the ability of fire-retardant materials; (3)Bringing the molecular sieve into woody material is in the trend of smog-retardant, low-poisonous, environment-friendly.

Abstract: Carbon nanotubes (CNTs) were modified by alkali, and carbon nanotubes epoxy composites samples were prepared by the hot pressing method. Dynamic characteristics of the composites were studied by experiments. The results suggest that carbon nanotubes can hardly enhance the first natural frequency of epoxy composite, but the change of second and third order natural frequencies are obvious compared with the first one. Damping properties of the composites are improved, and with the mass ratio of CNTs increasing, the first three order damping properties of composites are all increased initially followed by the decrease. The results also indicate that flexural elastic modulus of the composites is enhanced, the first and the second order dynamic elastic modulus is greater than it but the third order is opposite. The first three order dynamic modulus of elasticity moments of CNTs composites whose mass fraction is two percent are all high.

Abstract: According to the special construction environment and curing conditions of the freezing shaft inner and outer shaft lining in deep alluvium, first,configuration principle of high strength high performance concrete of freezing shaft in deep alluvium is proposed; Then raw materials are selected according to the preparation approach, and preparation experimental study of high strength high performance concrete is conducted with C60, C65, C70and C75 , and the optimum mixture ratio is obtained, and applied to the engineering practice, achieving remarkable effect.

Abstract: Electrochemical or electro co-deposition techniques have been used to deposit particles in metallic matrices to prepare composite coatings. The properties of the composite material can be improved by varying the type, size, amount and distribution of the incorporated particles. The effect factors of particles content in the coating were are presented in this review. The main focus is on the effect of surfactant, electrodeposition technology, zeta Potential and particles concentration in the bath on the content and distribution of co-deposited particles in the metal matrix.

Abstract: The basic properties of concrete can dramatically improve due to the unique structure of the nanosized particles. Namely, strength, frost resistance, fire resistance, corrosion resistance are increased, density and permeability are reduced; plasticity and water absorption are regulated. Despite of the huge number of advantages of nanomodified concrete, analysis of the use of nanoparticles shows that they are used quite seldom, as it requires a large cash outlay. It is not always profitable to use such additives. This article discusses some additives: magnesium nanoshpinel, microspheres, rice hull ash and metakaolin, astralenes, ferric hydroxide sol, carbon nanotubes, silica fume, nanosilica, MB-01, combined modifiers, based on iron hydroxide sol and silica sol. As well in this article sol-gel method as an additive in concrete is considered. The analysis shows that the use of nanosized particles can reduce a large amount of cement. As an addition, savings of the use are seen in reducing the cost of construction due to the low density with high strength. Accurate material consumption and maximum use of advantages of nanomodified concrete provide great prospects of implementation of this material in construction.

Abstract: Putting forward a new recycled aggregate concrete mixture proportion method based on the pulp content by researching the effect of pulp content on recycled coarse aggregate physical properties .Research on the cube compressive strength and splitting tensile strength of recycled aggregate concrete by the proposed method and results showed that:The proposed method can reduce the dosage of cement and sand, and increase the recycled aggregate concrete compressive strength and splitting tensile strength ;Establishing the relationship formula between splitting tensile strength and compressive strength of recycled aggregate concrete upon a large number of experimental data.

Abstract: Design concrete mix used in the PHC pile production, silica sand powder and slag powder as a concrete admixture, replace a certain percentage of Portland cement, under the premise of meeting the PHC pile production requirements. After the steam curing, determinate the demould strength of concrete and after autoclave curing, determinatie the compressive strength of concrete. Test results show that it is feasible for the use of silica sand powder and slag powder instead of Portland cement , in which the proportion of concrete admixtures up to 45%. Silica powder and the amount of slag powder were mixed with 150 kg/m³, 50 kg/m³, the concrete demould strength up to 49.1 MPa and the compressive strength after autoclave up to 89.0MPa, to achieve requirements of the national standard GB13476 .

Abstract: The effect of bittern on alkali-activated slag (AAS) cement and OPC was studied by testing on the strength and pore structure of the specimens stored in artificial bittern solution at certain periods. The experimental results show that the (AAS) cement exhibits excellent resistance to chemical attack of bittern. The significant increase of strength of (AAS) mortar stored in bittern solution was observed with the soaking time, and the strength increases very quickly before 27 d. But the strength of OPC decreases fast after17d. The more the contents of NaOH activator in AAS cement, the more the strength gained. And the more the contents of activator, the less porosity is. Curing the AAS cement in bittern environment leads to a reduction in the total pore volume and to a refinement of the pore structures.

Abstract: This paper analyzed the compound thermal isolation building blocks based on sintering shale hollow bricks. This work has redesigned the shape of building block, besides, optimized the holes in it and filled the thermal insulation materials in holes, thus the new compound sintering hollow bricks have a good thermal performance and mechanical performance. After the analyzing of the filling devices, the amount and value of productions have both improved.

Abstract: With ordinary Portland cement, fly ash, silicon powder, admixture and ultrafine copper-plated steel fibers with a diameter of 0.12 mm as raw materials, this paper studies the mechanical properties of ultrafine copper-plated steel fiber reinforced cementitious composite as well as their relationships. 14 groups of cube specimens, prism specimens and tensile test specimens were designed, fabricated and tested to obtain the mechanical properties of ultrafine copper-plated steel fiber reinforced cementitious composite; test specimens’ failure characteristics, contour plots of strains, increasing rules of cube compressive strength, prism compressive strength and tensile strength, as well as relationships among prism compressive strength, tensile strength and cube compressive strength were analyzed and studied at different fiber dosages, and corresponding mathematical models were established; the results indicate that, fiber dosage has the most significant impact on tensile strength increase of cementitious composite; the ratio of prism compressive strength over cube compressive strength is not correlated with fiber dosage; and the ratio of tensile strength to cube compressive strength is a linear function of fiber dosage. The research result is of important reference to design and application of ultrafine copper-plated steel fiber reinforced composite.