Advanced Materials Research Vols. 753-755

Abstract: The selection of mix proportion is the process of choosing suitable ingredients of concrete and determine their quantities with the object of producing as economically as possible concrete of notably strength. The current paper deals with the mix design of both an HSC and HSFRC constituted by volcanic aggregates from the quarries of Eastern Sicily in Italy. The mix design was carried out on eight different concrete mixtures by using the theoretical model developed by Feret – De Larrard’s and it is capable of simulating the experimental compressive strength. The HSFRC mixtures consider different volume fractions of fibers equal to 0% (HRC), 0.5% and 2% (HSFRC). Straight Polyvinylalcohol (PVA) and hooked-end steel fibers (ACC) were the two types of fibers employed in the study. Compression and tensile tests were carried out on specimens performed according to UNI codes in order to validate the mixture proportion method adopted. The HSFRC (0.5%) mixtures did not show great differences in mechanical performance by any variation of the fiber type (steel or PVA). The mechanical properties obtained by experimental tests give back a very good accordance with the theoretical prediction of the mix design procedure adopted, and with the data reported in the literature in terms of toughness.

Abstract: Phenolic foam offer a multitude of advantage for energy saving and fire, however, they are brittleness and need to be improved. Nanostructured inorganic particles are good modifiers to enhance the toughness, but the problem is that inorganic particles have poor compatibility with polymer materials. To solve this problem, here SiO₂ and Poly acrylic acid (PAA) hybrid nanoparticles were used as a reinforcing agent, which were prepared by silica sol and polyacrylic acid. The analysis shows that the hybrid nanoparticles effectively improve the compressive strength, the compressive strength and cell structures.

Abstract: The technique of linking the SEM photographs taken around the interfacial transition zone area is applied to observe the development of hydration products for lightweight aggregate and paste at the different curing ages. This research first determines the mixture proportions of the two types of concrete specimens with different aggregate unit weights. The lightweight aggregate used is the sludge kilned aggregate from Shihmen reservoir. The very small SEM samples to be observed are taken from the concrete compressive test specimens and must include both aggregate and paste. The research then observes the hydration products (such as CH, C-S-H) of calcium ion and the pozzolanic reaction on the samples. Finally it assesses if the aggregate will produce ion exchange with cement and generate the hydration products. The hydration products on either side of the interface with a range of 100μm are observed using 2000x magnification. From the results, it is found that (1) the development of hydration products of the lightweight aggregate concrete is similar to that of the normal-weight aggregate concrete, (2) the failure at the 91 days age is that the lightweight aggregate is sheared, (3) the bond stress of aggregate and paste is controlled by hydration products of paste, (4) the aggregate has not interacted with cement paste to produce hydration products, and (5) the development of hydration products proves that the amount of binder used in the concrete specimen will affects its compressive strength.

Abstract: This paper shows results of some properties of Magnesium oxysulfates (MOS) reinforced by fibers, specially the modulus of rupture (MOR) and durability. As showed by the literature [7], It is known that MOS cement can be formulated by the reaction between magnesium oxide and magnesium sulfate solution and like that of magnesium oxychloride (MOC) has very good binding properties. The resistance of MOS cements to abrasion is about 1.5 times that of Portland cement, but only 50% that of MOC cement. Its compressive and transverse strengths are superior to Portland cement but not as good as MOC cement. In this way, the authors formulated different matrices of MOS cement reinforced by polymeric and cellulose fibers. Also, calcium carbonate was employed. The results showed to be possible the use of MOS fibercements as an alternative for non-asbestos products such as panels and roofing elements besides the effective reduction of CO₂ emission to atmosphere.

Abstract: In order to utilize the converter slag that treated by the method of hot braised comprehensively. Using Jiugang hot braised slag as raw material, to determine the chemical composition of the slag with the semi-quantitative analysis and a number of chemical analytical methods. Using X-ray diffraction, optical microscopy, scanning electron microscopy and energy dispersive spectrometer to analysis the hot braised slag phase and iron phase. Also doing the measurement and analysis to the particle size of the slag, compressive strength and the grinding fineness. It was obtained the conclusion by the comprehensive analysis of hot braised slag that the hot braised slag can be returned to sintering process as solvent and it can also used in the construction、buliding materials and road engineering industry. It is a good suggestion that grounding the slag into a fine powder due to the poor effect of abrasion.

Abstract: Fly ash is a large amount of solid wastes produced from power plants, use of its resources has always been a matter of the government and experts are concerned. Combining with the characteristics of the nature of the fly ash, introduces the fly ash resource utilization in construction materials using some new approaches and application of the status quo.

Abstract: In view of the traditional ceramsite using a large number of high-quality natural clay and shale, the destruction of the environment problem, ceramsite was prepared by kyanite tailings in Hebei, The results show that when the kyanite tailings and clay was in the ratio of 7: 3, the preheating temperature was 500°C, preheating time was 15min, calcination temperature was 1100°C, heat preservation time was 15min, the apparent density of ceramsite is 816kg/m3, the particle strength of 851N.

Abstract: A high-rise residential building is the frame-supported shear wall structure. Testing found that concrete strength 6 pieces of shear wall of the tenth floor can not meet the original design requirements of C50 when the nineteenth floor was constructing. A way of replacing concealed column and corner column only by comparison an analysis.The safety of the structure was ensured and good strengthening effect was achieved by reasonable design of temporary support and construction, concrete selection and the whole deformation monitoring.

Abstract: On the basis of the important role of the overlying strata movement in safety prediction and control of coal mining, indoor similar material model test was conducted to study on the movement characteristics and the destruction regularities of the overlying strata from the deeply buried sublevel caving coal mining. The generation position and its extension regularities of overburden bed separation after the mining were analyzed. In addition, the impact of abutment pressure on movement conditions and structure damage of strata combination was explored. Lastly, characteristics of the rock beam subsidence and surface subsidence were discussed with the intention of providing basis for the design of pressure control of stratum movement and mines.

Abstract: Landslides are serious geological disasters in loess areas. In order to study the effect of the filling caves in the edge of loess tableland on loess slope stability, the slope stability of sliding from the caves was calculated in irrigation when caves were filled with compacted soil, lime soil, lime-ash soil and non-filled. The results show when caves are filled with lime soil the slope stability is the highest. The effects of variability of the physical and mechanical property indexes of caver filler on loess slope stability were researched further. The results show that (1) the variation coefficients of unit weigh and the shear strength indexes of cave filler lime soil have small effect on the average value of safety reserve, but have big effect on the standard deviation of safety reserve, which explains that the design risks increase while the variation coefficient increasing. (2) with the increase of variation coefficients of unit weigh and the shear strength indexes of cave filler the failure probability increases. Especially when variation coefficient is bigger than 0.3, the failure probability of loess slope is very sensitive to variation coefficient. (3) the effect of correlation coefficient among unit weight and the shear strength indexes of cave filler on failure probability increases with the variation coefficient increasing. It is very important to guarantee filling project. Good quality of filling construction will decrease the variability of cave filler, heighten the stability of loess slope, and decrease the occurrence of loess disasters.