Abstract:From the view point of chemistry, the function of water in different types of cementitious materials is analyzed. In some books about cement technology and cement chemistry, authors say:“It should be noticed, that the term, hydration, can not be used to describe the reaction between water and cementitious materials, even Portland cement.” In the fact that the reaction of water with cementitious materials may results in hydration and hydrolysis, water sometimes may only play the role of solvent to dissolve the reactants. Moreover the water is not the reactant, but is even the reaction product.

Abstract:The application of nuclear magnetic resonance cryoporometry（NMRC）for cementitious materials was analyzed. The constant in GibbsThomson equation that described the relationship between decrease value of ice melt point and pore size was obtained via measuring some mesoporous molecular sieve with certain pore size. The constant was then used to analyze the white cement samples with different mW/mC at different ages, and the possible error was discussed. The preliminary result shows that NMRC can give more details of pore size distribution of white cement samples than other methods, such as the volume of close micropore.

Abstract:The influence of highsilicon limestone on mineral structure and performance of belitebarium calcium sulphoaluminate cement clinker were investigated by thermal analysis, petrographic analysis, Xray diffraction and scanning electron microscopyenergy dispersive spectroscopy. The results show that highsilicon limestone has low decomposition temperature, which can promote the development of C3S by adding small quantity. The formation and development of C3S is hindered by αquartz while C3S is formed easily by mixing magnesite and dolomite in highsilicon limestone at low temperature. When mass proportions of highsilicon limestone and ordinary limestone is 1.0︰5.0, the compressive strength of this cement at 3, 7, 28 d is 37.9, 60.3, 87.9 MPa respectively, which shows excellent improvement of mechanical properties.

Abstract:An experimental method of electrochemical realkalization for carbonated concrete was designed and two reasonable evaluation indexes for its effectiveness, pH value and migration content of sodium ion, were proposed. Further, effects of types and concentration of electrolyte solution, realkalization time on the effectiveness of electrochemical realkalization for carbonated concrete were investigated. The results show that the pH value increases but increase rate of pH value slows down with the increase of realkalization time. For the same electrolyte solution, the higher the electrolyte solution concentration, the higher the migration content of sodium ion in carbonated concrete after realkalization is. For the same concentration of different types of electrolyte solution, the migration contents of sodium ion in carbonated concrete after realkalization are different.

Abstract:Synthetic process of amide type polycarboxylate based superplasticizer was studied. Polyether amine（PN220） and polyacrylic acid（PAA） were used as the monomers and directly polymerized into superplasticizer. The effects of the relative molecular mass of PAA, monomer ratio, polymerization temperature and time on waterreducing rate and fluidity retention of the product were investigated through experiments. The orthogonal experiment is designed to find out the optimal synthesis technique. The performance of the product is compared with the superplasticizer which is prevailing in the market and synthesized by polyethylene glycol monomethyl ether（MPEG） and methacrylic acid. The results show that the former has excellent slump retention and it is suitable for preparation of concrete demanding outstanding slump retention.

Abstract:Crack distribution, mechanical performance recovery of selfhealing engineered cementitious composites(ECC) materials under wet/dry conditioning cycles and nanoidentation analyses of the microphases in ECC at 0.3%, 0.5%, 1.0% and 2.0% preloading were investigated. The results suggest that ECC has many characteristics that contribute to selfhealing behavior. Majority of ECC cracks are below 30 μm in width. Both ultimate tensile strength and tensile strain capacity of the majority specimens at reloading are higher than the control specimens. The modulus of elasticity, hardness and stiffness of healed products is about 34.8 GPa, 1.6 GPa and 0.1 mN/nm respectively.

Abstract:The pullout and fourpoint tests of thinwalled plate specimens were carried out to investigate the bonding and overlapping performance of textile in fine grained concrete. The experimental results show that the warp yarns and the surface treatment of the textile have significant influences on the interfacial bond performance between the textile and the fine grained concrete. In addition, for the textile covered with or without sand, with the increase of the initial bond length of carbon fiber yarn, the average interfacial bond strength has a falling trend, and when the initial bond length is longer than 35 mm, it is enough to ensure that carbon fiber yarns can have sufficient bond to the fine grained concrete and can not be pulled out. For the textile covered with fine sand, if the overlapping length of carbon fiber is longer than 60 mm, the requirement for the stress transfer between fiber yarns can be met. At the same overlapping length, the enhancement capacity of the textile using the binding overlapping are better than that of the textile using the sticking overlapping.

Abstract:Adopting the grey system theory, the carbonation equations for concrete with different water cement ratios and different fly ash contents are established, different grey models（GM）are compared and analyzed. Based on the forecasting accuracy variation of the models, a basic method to establish grey forecasting model for concrete carbonation depth is therefore proposed. Experiments show that GM forecasting is of good pertinence and high analog accuracy, and is capable of selfupdating when new information is found. As a conclusion, GM forecasting is a feasible and practical method with many field of applications.

Abstract:In order to analyze the effect of freezethaw cycles and strength grades of concrete on tensile property, concrete samples of different strength grades undergoing rapid freezethaw cycles were subjected to uniaxial tensile experiment and splitting tensile experiment. Tensile peak stress and splitting tensile strength were measured and simple mathematical models were proposed. Research shows that as freezethaw cycles increase, the tensile mechanical and deformational properties of concrete are reduced; the higher the strength grade is, the more slowly these properties are lowered.

Abstract:To study the effect of EPS on the toughness of plain concrete, the EPS concrete with 10%，20%，30%，40%，50% EPS volume fraction were prepared. Taking specific energy absorption as the index, the toughening effect of EPS with different EPS volume fraction under impact loading were studied using a 100mmdiameter split Hopkinson pressure bar（SHPB）apparatus, and the toughening mechanism of the concrete was discussed. The results show that the toughness of the EPS concrete improves with increasing average strain rate, which shows obvious strain rate dependence. The toughness of EPS concrete improves in some degree with 10%30% volume fraction of EPS. And the optimum volume fraction of EPS is 20%. Its toughing effect reduces somewhat when the EPS volume fraction reaches 40%50%.

Abstract:Carbonation is the key factor that causes the corrosion of the reinforcing steel embedded in concrete. The surface layers of the concrete specimens were treated by superabsorbent resin（SAR）synthesized in situ， i.e.， the concrete surface was impregnated by the precursor solution of poly（acrylic acidcoacrylamide）with initiator and crosslinker， and then the impregnated concrete was radiated by infrared ray to synthesize SAR in situ. The resistance to carbonation was studied for the concrete treated with SAR in comparison with the hydrophobic waterproofing agent of alkylalkoxyl silane（AAS）. The carbonation depth of concrete after the accelerated carbonation testing was measured and the ingress of carbon dioxide was evaluated quantitatively by the sophisticated technique of Xray diffraction（XRD）. The results show that the concrete specimens treated with SAR have higher resistance to carbonation than that of the concrete specimens treated with AAS and the control concrete specimens.

Abstract:In order to evaluate and estimate rutting resistance of asphalt mixtures more conveniently, the softwear PFC2D was applied to simulate the triaxial shear test of asphalt mixture based on the discrete element method（DEM）, and the simulation results are compared with laboratory test results. Results show that the discrete element simulation and laboratory test have good correlation, which verifies the applicability of the model, while the virtual test method based on this model can be established to evaluate and predict the rutting resistance of asphalt mixtures.

Abstract:The effect of admixture and corrosion inhibitor on rebarprotecting properties of seawaterseasand concrete was studied by testing polarization potential and mass loss of rebar in seawaterseasand mortar. It is concluded that the fly ash, slag have limited improvement on the rebarprotecting properties of seawaterseasand concrete whereas metakaolin has a marked effect of improvement. When metakaolin is added, the rebar polarization potential obviously moves to the positive. In addition, triethanolamine corrosion inhibitor has the good effect on improving the rebarprotecting properties of seawaterseasand concrete. The combination of metakaolin（20%,by mass）and triethanolamine（1.5%,by mass）has an significant effect on the rebarprotecting properties of seawaterseasand concrete, the rebar polarization potential is the same as the ordinary concrete made with fresh water and sand, rebar mass loss is significantly reduced, rebar cured for 420d is not corroded at all.

Abstract:Effect of evaporation rate of water on the cement mortars plastic shrinkage cracking was investigated by changing temperature, humidity, light exposure and wind speed with different watercement ratio and the evaporation rate was calculated by simulation of mortar in small mold. The constitutive equation of plastic shrinkage cracking on evaporation rate of water as well as the constitutive equation of plastic shrinkage cracking on both evaporation rate and watercement ratio were established, which can be used to predict the plastic shrinkage cracking tendency of cement mortar.

Abstract:An experimental research on the influence of defects in recycled aggregate on mechanical properties of recycled aggregate concrete（RAC） was conducted. Concretes with two waterbinder ratios（0.59 and 0.25）were broken into recycled aggregate（RA）， which might induce defects in the forms of damage of gravel in RA and mortar attached to RA. A type of thermal treatment， i.e. heating under temperature 620℃ for 3 h， was employed to remove attached mortar. Tests were conducted to determine compressive strength， tensile splitting strength and fracture energy of the concrete. The experimental results reveal that the mechanical properties of RAC are significantly lower than those of natural aggregate concrete. As to RAC with a low waterbinder ratio， gravel damage is a main factor causing the decrease in the mechanical properties， while with a high waterbinder ratio， attached mortar is such a factor. Among the properties measured in this investigation， water absorption and fracture energy are the two factors that can sharply reflect influence of the defects in RA during the broken process. It is suggested that prior to mix proportion design and preparation of concrete using recycled aggregate， it is necessary to obtain the details of demolished concrete such as its strength grade or waterbinder ratio， and of the characteristics of defects in recycled aggregate.

Abstract:In order to investigate the aging mechanism and degradation process of intumescnet coating, the results of fire tests are reported. FTIR tests and SEM tests were conducted on the intumescent coating after hydrothermal aging tests. Results of the degradation mechanism study reveal that the hydrophilic components in intumescent coating move to the surface of the coating and can be dissolved by moisture in the air. Compared to specimens without hydrothermal aging tests, after 42 cycles of hydrothermal aging(to simulate 20 years of exposure to an assumed exposure environment), the effective thermal conductivity of typeU intumescent coating is 50% higher and that of typeA intumescent coating is 100% higher than fresh coating.

Abstract:Fracture tests were performed for epoxy resin asphalt mixes for steeldeck pavement using single edge notch beam specimen at -20,-10,0 and 10℃. Dynamic mechanical analysis(DMA) was implemented for epoxy resin asphalt at temperature range from -30 to 20℃, and SEM photos of section of tensile specimens were used to analyse microstructure of this material. Results show that fracture toughness of the epoxy resin asphalt mixes with crosslink degrees of 58.4%, 67.3%, 71.4% and 75.3% is reduced with increasing temperature, while fracture energy of that increases. Fracture toughness and fracture energy of four different crosslink degree epoxy resin asphalt mixes correlate with dynamic modulus of binder, or crosslink degree and temperature. Relationships are found between fracture parameters of mixes and dynamic modulus of binder, or crosslink degree and temperature. SEM photos show that the section of low crosslink degree epoxy resin asphalt is irregular, which could absorb more fracture energy.

Abstract:Aging mechanism of quicklime and application of aged lime in conservation of cultural relics were studied by means of scanning electron microscope(SEM）and Xray diffractometry. Results show that calcium hydroxide crystals undergo both substantial size reduction and clear morphological change to form acicular Ca(OH)2(50nm in diameter and 200nm in length）and platelike Ca(OH)2 (100200nm in size）crystals in the course of aging. Meanwhile, research results indicate that the nano size and high reactivity of aged lime particles prompt the improvement of the mechanical properties of sticky ricelime mortar and hydraulic conductivity of Ca(OH)2alcohol dispersions, which solves the problems of low dissolution and permeability associated with the use of Ca(OH)2 solutions. This study is expected to found the stone for application of aged lime in conservation of cultural relics.

Abstract:In order to solve the problem that lowtemperature impact toughness of traditional highstrength lowalloy Hbeam is lower, from taking account of composition design, boron was added into this type of steel for the first time, and the effect of boron on microstructure and mechanical properties was investigated. The results show that compared with nonboron steel the strength and the plasticity of boroncontained steel are increased slightly, moreover the impact toughness is improved greatly, especially at low temperature. The microstructure is refined to a certain extent because of the smaller and evenly distributed Nb（C,N）precipitates and also the brittle fracture of the materials is restrained by boron addition, so that the ductilebrittle transition temperature is significantly reduced.

Abstract:Petrography analysis, accelerating mortarbar test（AMBT）and autoclave method were used for examining the alkali reactivity of sands and gravels from three regions along Xiangjiang river, that is, Xiangyin, Wangcheng and Xiangtan. Results show that：there are no obvious differences in mineral constituents among the sand samples as well as among the gravel samples. The sands are composed of quartz, feldspar, mica particles and greywacke fragments. The gravels are composed of about 50%（by mass）of both quartzite and greywacke. A fair amount of cryptocrystalline and microcrystalline quartz are noticed in the greywacke in both sands and gravels. The gravels are alkali reactive in both AMBT and autoclave method. The sands are reactive in AMBT, while in autoclave method the expansion is linked with the way of sampling methods. The alkali reactivity of both sand and gravel is attributed to the cryptocrystalline and microcrystalline quartz in greywacke in them. Preparation of representative samples of sands and gravels is the key for both petrography analysis and autoclave tests for reliable identification of alkali reactivity.

Abstract:A method to remove chloride in reinforced concrete was proposed by anodic oxidation of silver plate in the pore solution with chloride content over critical value. The result shows that after anodic oxidation of silver plate the chloride concen in pore solution is reduced, the polarization resistance of rebar is improved to the range of safety, the electric resistance of concrete, the electric resistance and capacitance of passive film on the surface of rebar and the diffusion impedance coefficient of reinforced concrete are improved with the result that the performance of anticorrosion of rebar in concrete is improved.The silver plate can be used repeatedly.

Abstract:In order to explore the stress and strain relation in the pavement layers under traffic load from a mesostructural perspective, the singlescale discrete element model of asphalt pavement structure was built using discrete element method(DEM). The stress and strain at the bottom of the asphalt concrete layer under vertical load were calculated. The validation of discrete element model of asphalt pavement structure was conducted by the comparison of discrete element prediction with the results from the classical program. The distribution and volumetric fraction of coarse aggregate, asphalt mastic and air voids were taken into consideration at the bottom of the asphalt layer in the validated discrete element model to build the multiscale structure of asphalt concrete pavement. The tensile stress and strain in asphalt mastics and interface between aggregate and mastic were obtained and compared with the results from the singlescale model. Results show that the stress and strain in multiscale structure is heterogeneous distribution. The tensile stress at the interface between aggregate and mastic is much higher than that in mastic. The ratio of stress at interfaces to the stress in mastics increases as the mastic stiffness decreases. The pavement design based on singlescale model may underestimate the tensile stress at interface between aggregate and mastic and overestimate the tensile stress in mastic.

Abstract:A large number of laboratory tests were carried out, which took high temperature, fatigue and moisture resistance as main test items. The research not only evaluated the impact of waiting time for paving on the performance of epoxy asphalt from three aspects, but also integrated these items and put forward suggestions on the value of waiting time for paving by the grey relationship analysis methods. The results indicate that if the waiting time for paving is less than 30 min, the performance of epoxy asphalt will remain unchanged; however, when the grey connection performance declines to 80%, it will take the longest waiting time for paving, which can be as long as 80 min. This method can be applied to the researches and developments of epoxy asphalt as well as the evaluation of engineering practice.

Abstract:In view of the phenomena that no Ca（OH）2 exsits in the hydration products of alkalislag cement and its carbonation is more serious, water glass was selected as the alkali activater, and XRD and SEM were adopted to study carbonation products and microstructure of alkalislag cement pastes, while the pore structure was researched by nitrogen adsorption. The results show that the carbonation takes place directly on the CSH gel and calcium carbonate, the carbonated product of alkalislag pastes exists mainly in the form of calcite. After carbonation, the Ca/Si of CSH gel decreases, while surface area of the pastes increases and the average pore diameter reduces. The change in cumulative volume of pores varies with modulus of water glass.

Abstract:A new type of magnesiaphosphate cement（MPC）that has high strength and controllable setting time was prepared by low acidity phosphates （NH4）2HPO4 and K2HPO4 as raw materials. The results show that the new MPC has better fluidity and longer setting time with the decrease in （NH4）2HPO4/K2HPO4 molar ratio in the case of fixed mw/mc ratio and retarder dosage. Early compressive strength of the new MPC after adding K2HPO4 decreases slightly， while 28d compressive strength of the new MPC is all above 70 MPa. The main hydration products of MPC are NH4MgPO4·6H2O and KMgPO4·6H2O.

Abstract:Effects of five kinds of waterreducing agents, calcium lignosulfonate(CLS), modified calcium lignosulfonate(GCL16A), aminosulfonic based superplasticizer(ASP), sulfonated naphthalene formaldehyde(FDN） and sulfonated melamine urea formaldehyde resin(SMUF), on the durability of cement mortars were studied including impermeability, carbonization depth and shrinkage. The research results indicate that durability of cement mortar mixed with SMUF is the most excellent; durability of cement mortar mixed with GCL16A and FDN is next; that mixed with CLS is the weakest.

Abstract:An experimental investigation on the dynamic mechanical properties of the rubberized concrete (RC）with rubber chips of volume fraction from 0%20% was conducted using splitHopkinson pressure bar(SHPB). For the same type of specimens, stressstrain curves under 4 different strain rates, were obtained. The test results show that the rubberized concrete has obvious ratedependent mechanical behavior, its peak stress, ultimate strain of elasticity exhibits significant effect of strain rate strengthening. For the same volume fraction of rubber chips, this effect strengthens with the increase of strain rate. For the same strain rate, the deformation performance of rubberized concrete increases with the increase of volume fraction of rubber chips. From the point of view of the failure mode, impact resistance of rubberized concrete is much better than that of normal concrete.

Abstract:The coldpressing technique, which incorporates the principles of cement chemistry and composite material was employed to produce the recycling coarse aggregates using B23, B3, B4, and B6 categories construction residual soils with extremely low utilization rate and poor properties so as to raise the utilization rate and value of the abovementioned construction residual soils. The results show that the specific gravity of recycling coarse aggregate is about 1.80 in the ovendry(OD) state and 2.05 in the saturatedsurfacedry(SSD) state; the absorption capacity is approximately 15.5%(by mass); the bulk density (i.e. unit weight) is 1103 to 1216kg/m3; the air void is about 35.3%(by volume); the particle cylindrical crushing strength ranges from 17.06 to 23.33MPa; other characteristics meets reguirement set forth in ASTM C33. For this reason, the developed recycling coldpressing coarse aggregates can not only meet the specifications for green building materials, but can also be used to reduce the energy consumption and CO2 emission resulted from producing the sintering recycling aggregates.