Advanced Materials Research Vols. 450-451

Abstract: The light transmitting cement mortar is to rely on a large number of optical fiber embedded in the block transferring light from the light side surface to the dark side. In this article, the preparation method of light transmitting cement mortar (LTCM) was introduced and the strength and light transmitting properties of LTCM were tested too. The results show that the LTCM can get higher light transmitting ratio and can also achieve, even exceed the light transmitting ratio of the 70g A4 print paper in the light wavelength range of 520~630nm.

Abstract: Two kinds of polymer latex and fiber are used to improve the physical performance of cement mortar. The influences of the fiber and latex added alone and together on the compressive and flexural strength, toughness, bondability, and compactedness of the hardened mortar were studied, and the modified mechanism was also discussed by SEM and XRD. The results showed that both of the latex and fiber can improve the compressive and flexural strength of mortar in low content, decrease the porosity, improve the toughness and bond flexural strength significantly, and delay hydration process of cement mortar. The effect of fiber-latex added together was better than that of two matters added separately. The optimized components for fiber-latex hybrid were: ACE12% + PVA1.6 kg/m3.

Abstract: In this work, the effect of superplasticizer type and dosage on early-age shrinkage of ordinary Portland cement (OPC) and rice husk ash paste (RHA) was investigated. The OPC and RHA pastes with a water/binder materials ratio (W/B) by weight of 0.22 and various dosages of polycarboxylate ether-based superplasticizers (PCE) and sulphonated naphthalene formaldehyde condensates (SNF) were investigated. RHA was partially substituted of 0%, 10% and 20 % by weight of OPC. Volumetric shrinkages of the pastes at the first 72 hours of hydration have been found to range from 0.28 to 12.26 mm3/g and from 0.20 to 9.04 mm3/g of binder materials for SNF-based and PCE-based superplasticizers, respectively. The PCE-based superplasticizer can decrease an increase in shrinkage of the OPC and RHA pastes higher than those of containing the SNF-based superplasticizer.

Abstract: From the experimental research, the cube compressive strength and prism compressive strength of combined aggregate concrete are compared. Based on regression analysis, the influence of different substitution ratio of lightweight aggregate, age of concrete and water-cement ratio are studied, and the age coefficient is analyzed. According to the test results, the formula of compressive strength of combined aggregate concrete is given.

Abstract: The incorporation of SBS into crumb rubber modified asphalt is investigated to enhance binder properties and storage stability in this paper. In order to gain the high quality of road pavement asphalt, the preparation process is optimized. The main objective of this study is to enhance the properties of crumb rubber modified asphalt through the addition of Styrene-Butadiene-Styrene (SBS) and analysis the effect of SBS type, preparation temperature and time exert on the properties of SBS /crumb rubber composite modified asphalt. The optimal preparation condition as follow: the swelling temperature for two mixed modifiers: 180 °C, swelling time: 1h; Shearing temperature: 180 °C, shearing time: 1h; Breeding temperature: 170 °C, breeding time: 3h. The results demonstrated that the properties of SBS/crumb rubber composite modified asphalt can meet the requirements of Grade C standard on SBS polymer modified asphalt.

Abstract: Experiment with intensity level for the LC30 ceramsite concrete as the research object, changing the content of cement, GRT fiber, rubber powder by the orthogonal test to configure GRT fiber—rubberized haydite concrete samples, maintenance samples 28d in standard conditions and respectively testing their modulus of elasticity、standard compressive strength and apparent density. Through the analysis of the test data, using regression method to establish the GRT fiber—rubberized haydite concrete static compression modulus of elasticity experiential formula and use new test data to compare the value of calculation. By comparing test values and calculated values proved availability of the regression formula.

Abstract: The three key oxide molar ratios of geopolymer concrete were studied in this paper: n(SiO2)/n(Al2O3)，n(Na2O)/n(Al2O3) and n(H2O)/n(Na2O). The effect of each oxide molar ratio was assessed by electric flux method. It was found that resistance to chloride ion of geopolymer was increased with increasing n(SiO2)/n(Al2O3).However, there was a limit beyond which this performance improved; it performed better with the increasing of n(Na2O)/n(Al2O3) but worse with the increasing of n(H2O)/n(Na2O). With the same amount of cementitious material, resistance to chloride ion of geopolymer concrete was better than that of common concrete.

Abstract: A new hybrid-fiber Engineered Cementitious Composite (ECC) containing 1.25% steel (SE) fibers and 0.75% Polyvinyl Alcohol (PVA) fibers is proposed, and material properties of the new ECC mix are tested in this paper. The compressive strength, modulus of elasticity, modulus of rupture and tensile properties under various strain rates of the new hybrid-ECC mix are investigated experimentally. The tested results are compared with those for a normal concrete mix, as well as those for other mono-fiber and hybrid-fiber ECCs reported in other literatures.

Abstract: The influence of the accumulated structure formed by the aggregate particles on permeability and strength of permeable concrete was investigated by three-dimensional geometry method, which was proved by theoretical analysis and experimental study. In theoretical analysis, the accumulation structure of the aggregate was in a steady or quasi-steady state, particle size distribution was optimized to obtain the desired permeability coefficient and sufficient strength. The results showed that it is more appropriate that the ratio of the secondary particle size is 0.2d - 0.4d when the large particle size is d. To obtain good permeability in experimental study, the large voids have a large proportion in all kinds of voids statistics distribution of aggregate accumulation of structure in pervious concrete. The percentage of fine particles needs to be controlled to achieve the desired permeability and concrete strength.

Abstract: In this study, the corrosion process of enamel-coated deformed rebar completely immersed in 3.5 wt.% NaCl solution was evaluated over a period of 84 days by EIS testing. Three types of enamel coating were investigated: pure enamel, 50/50 enamel coating, and double enamel. Surface condition of the enamel coatings that were intentionally damaged prior to corrosion tests was visually examined at different immersion times. After 84 days of testing, the damaged coating areas were characterized by SEM, and the corrosion products on and adjacent to the damaged areas were collected and analyzed by XRD. Corrosion initiated at the damaged locations with no undercutting of the coating observed. The 50/50 enamel coating had the least corrosion resistance, due to its interconnected pore structure, and prior damage drastically reduced the corrosion resistance of pure and double enamel coated rebar.