Applied Mechanics and Materials Vols. 584-586

Abstract: In Xinjiang, by making use of cotton stalks after cotton picked, people researched and developed a kind of walling material that is cotton stalks cement-based blocks, elaborated its preparation methods, and evaluated its technology effect of cotton stalks cement-based block material. Results show that the cotton stalks cement-based block material have good properties like wide source, easy processing and wonderful performance; by soaking cotton straw broken material with alkali liquor, made cotton straw plant fiber reinforced material and the cement matrix have good interface adhesion; the block material is provided with load-bearing, heat preservation performance and cracking resistance, it can be used for low-rise buildings bearing wallboard and retaining wall of multiple floors in cotton planting region.

Abstract: The objective of this article is to provide a paving project for steel bridge deck based on a new composite bonding system of Epoxy resin/emulsified-Asphalt/Cement (EAC). Reinforced both by Cement and emulsified-Asphalt, the resin-based material has reflected good performances, especially rutting deformation at high temperature and adhesive strength with steel blocks, which should be satisfied to long-span steel bridge deck.

Abstract: The effects of different forms of CaO on performances of cementitious binders containing 50 wt. % GGBFS powder are studied using compressive strength testing, hydration heat and X-ray diffraction measuring, microstructure measuring, and deformation testing. Results show that, the use of analytical-grade CaO or calcined CaO expansive clinker produces a higher mechanical strength than analytical-grade Ca (OH)₂ for mortar samples. The mortar containing analytical-grade CaO or calcined CaO expansive clinker shows a strength increase higher than the reference before 14 days of curing, but a litter lower than the reference after 28 days. With the increase of curing age, the diffraction peaks of Ca (OH)₂ gradually weaken, while those of C-S-H and hydrotalcite gradually increase, contributing to a gradual increase in strength of GGBFS pastes. Compared to analytical-grade CaO, the expansive process of calcined CaO expansive clinker matches better to the deformation history of mortar containing large content of GGBFS. This work is of great significance to explore the potential use of different forms of CaO as an alternative activator for GGBFS.

Abstract: The influence of sodium citrate on the hydration capacity of hemihydrate calcium sulfate whiskers was investigated. The products were characterized by FTIR, SEM and XRD.The results show that the absorption of the sodium citrate on the surface of the hemihydrate calcium sulfate whiskers is not uniform, and the adsorption state also changed with the amount of sodium citrate. Sodium citrate plays role on the hydration capacity of hemihydrate calcium sulfate whiskers.

Abstract: The superplasticizer is very useful to reduce mixing water in fresh concrete, which results in the enhancement of watertightness and strength of hardened concrete. But it has a limit of not preventing steel bar embedded in concrete from corrosion under critical corrosive environments. Thus, this study aims at developing a nanohybrid agent chemically combining PCA admixture with anionic charge of clay. As results of concrete tests using general PCA superplasticizer and new one developed, it can be found that new plasticizer has higher performance in terms of time-dependent slump and air content loss, compressive strength, and anti-corrosion. It is expected for new superplasticizer, called the PCA-HT NHA, to be applicable to concrete under severe corrosive environments.

Abstract: The frost resistance of low strength concrete is researched. In order to evaluate the effect of different content of silica fume on frost resistance，the quality of the cement 6%, 9%, 12% silica fume are respectively added into concrete. Freezing-thawing test results show that: the silica fume concrete has good frost resistance. Content of silica fume on concrete is not almost effect to quality loss rate. In 0-250 times of freezing-thawing cycle range, it is smaller that relative dynamic elastic modulus change rate. Relative dynamic elastic modulus of ordinary concrete decreases rapidly after 250 times of freezing-thawing cycle while dynamic elastic modulus decrease rate of the silica fume concrete tends to slow. The freezing -thawing cycles up to 350 times, silica fume concrete relative dynamic elastic modulus is 1.5 times that of ordinary concrete that show the silica fume concrete frost resistance is better than that of ordinary concrete.

Abstract: PVA fiber reinforced cement-based composite is a new high-performance cement-based composite material, which usually manufactured with PVA short fibers (does not exceed 2.5% vol.) and cement-based matrix. It has a significant strain-hardening characteristic and excellent crack controlling ability. Its ultimate tensile strain is up to 3% and crack width is not exceed 100μm. PVA fiber reinforced cement-based composite can be utilized to fabricated high energy absorption opponents, such as protective shield, seismic joint, impact-resistant site, etc. In this paper, the basic mechanical properties of PVA fiber reinforced cement-based composite has been tested and verified first. Then the impact resistance of PVA reinforced cement-based composite has been investigated via drop weight impact test, and compared with ones of plain concrete and steel fiber reinforced concrete with the same strength grade. Through analyzing the test results, it is concluded that PVA reinforced cement-based composite’s impact energy absorption is 48 times than plain concrete, and 9 times than steel fiber reinforced concrete respectively. The impact numbers of PVA reinforced cement-based composite is slightly lower than steel fiber reinforced concrete, but its impact absorption energy after initial cracking is 15 times than steel fiber reinforced concrete. In conclusion, PVA reinforced cement-based composite is an excellent impact material.

Abstract: With the development of modern building design and construction technology, high strength concrete technology were getting more use in engineering and more requirements. The authors produced C80 HPC by using Portland cement, blast furnace slag, micro bead and Flyash as cementitious material, have prepared the concrete with grade of C80, low pumping resistance (rewinding time less than 6s), low shrink (72h early self-shrinkage value at 0.028%), high workability (slumps over 240mm and divergence over 700mm) and high durability (diffusion coefficient in concrete after 28d was 1.35×10^-12 m²/s), which would match the requirements of the Guangzhou East Tower.

Abstract: Firstly, based on contrast to the the merits of conventional asphalt, natural colored asphalt, bitumen thermoset and thermoplastic light colored asphalt, the paper proposed the base asphalt selection method. Then on the basis of comparison of the performance of organic pigments and inorganic pigments of paint, the pigmentselection method was identified. Thirdly, the paper compared the color characteristics of different types of stone and provided some recommendations on aggregate selection. Finally, the paper briefly introduced the design method and technical requirement of colored hot-mix asphalt material.

Abstract: Cement asphalt mortar (CA mortar) is one of key structures of slab ballastless high-speed railway. Cement and asphalt emulsion are the main two components of CA mortar, making it possess the viscoelastic properties of viscoelastic materials, which is one of the infancy of the current study. In this paper, DMA method was adopted to investigate the viscoelastic properties of CRTS II CA mortar. Viscoelastic properties of CA mortar at different temperatures were investigated and were compared with the numerical simulation results of Burgers model. The results of the simulation fit in well with the data from the experimental-scale column, so we can study the dynamic modulus of CA mortar using the Burgers model in the temperature range of CA mortar.