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The article provides information about the stress state protective and decorative coatings during aging. The influence of the discrete nature of the substrate on the change in the stress state of the coatings from the action of the wind load is considered. It was revealed that for each type of coating there is its own critical value of the pore size (unfilled paint), the excess of which leads to cracking of the coatings. A method is proposed for selecting the optimal coating thickness.

This paper presents an analytical method for calculating the cracking moment of concrete beams reinforced with fiber reinforced polymer (FRP) bars, which considers the non-linear behavior of concrete in the tension zone and the contribution of FRP reinforcement. Theoretical cracking moments obtained by the proposed method were verified with the experimental results and the theoretical results calculated according to ACI 440.1R-15. The comparison results show good agreement between theoretical and experimental data. A parametric study on the effect of longitudinal FRP reinforcement ratio and elastic modulus of FRP on the cracking moment of FRP reinforced concrete beams also were done by using the proposed method. The parametric study results show that both longitudinal reinforcement and modulus of elasticity of FRP significantly affect the cracking moment of FRP reinforced concrete beams. Moreover, parametric study results also clarify the weakness of ACI 440.1R-15 in determining the cracking moment of concrete beams reinforced with a large amount of FRP reinforcement ratio and with high modulus of elasticity of FRP.

Information on the stress state of protective and decorative coatings during the curing process, in particular on the cohesive state of destruction, is given. The influence of the type of substrate on the change in internal stresses in the coating is considered. It was revealed that the greatest value of shear stresses is observed in coatings on a heavyweight concrete substrate. The subsequent increase in temperature after curing to 50°C leads to an increase in the value of the normal stresses. The probability of cracking of coatings during thermal aging is estimated. It was revealed that during aging there is an exponential decrease in the cohesive strength of coatings and an increase in internal stresses. Aging tends to increase the likelihood of cracking of coatings. The change in stresses in coatings as a result of seasonal fluctuations in air temperature is considered.

In this paper, the brittleness coefficient, elastic modulus-to-strength ratio, drying shrinkage and autogenous shrinkage and cracking sensitivity were used to investigate the effect of styrene-acrylic emulsion (SAE) on crack resistance of cement-based materials under ultralow water binder ratio (0.22). Then the pore structures, hydration products and surface morphology were also studied to explore the mechanism of SAE on improving the crack resistance of cement-based materials. Results show that, the addition of SAE significantly reduces the elastic modulus, brittleness coefficient, elastic strength ratio, drying shrinkage and autogenous shrinkage of the specimen. The cracking susceptibility is also decreased by the incorporation of SAE and when the dosage of SAE was 5%, the initial cracking time would be extended by 43 hours. In addition, incorporation of SAE can reduce the amount of pores that have an adverse effect on shrinkage, refine the microstructure and decrease the calcium hydroxide formation and microcracks of cement-based materials. Such results would be expected to provide guidance on enhancing the anti-cracking ability of high-performance cementitious materials by the dosage of SAE under low water-binder ratio in practical engineering.

In order to solve the problem of workability and durability of concrete caused by poor particle shape and morphology of manufactured sand and high content of stone powder, which leads to crack problems of concrete, the tensile strength, elastic modulus, shrinkage performance and adiabatic temperature rise performance of manufactured sand concrete were studied in this paper. And the cracking risk factor (the reciprocal of the anti cracking safety factor) of the concrete with the special admixtures and the crack resistant functional materials was calculated by according to GB 50496-2018. The experimental results show that the elastic modulus and tensile strength at the age of 28 d of the test concrete are increased from 31.0 GPa to 34.6 GPA and 2.91 MPa to 4.23 MPa, respectively. The shrinkage performance and adiabatic temperature rise of the concrete are reduced from 98 με to 65 με and 38.9°C to 38.4°C, respectively. The risk factors of surface and center crack resistance of mass concrete floor are 0.52 and 0.75, so the concrete under inspection will not crack.

This paper presents the experimental testing of eccentrically compressed reinforced concrete columns. There are experimental results of crack resistance of non-strengthened (control) and strengthened RC columns in the tension zone. The columns were strengthened by carbon fiber reinforced polymers (CFRP). As a result of experimental studies with the columns strengthened by CFRP, we obtain that the width of their crack decreased by an average of 33%. The eccentric compression load of the crack’s appearance increased from 40 kN to 60 kN for strengthened columns.

In order to restore worn parts during repair work, it is often used to press the repair bushings. While assembling joints, cracks may form in the spanning part (bushing), as it may have surface and structure defects. Therefore, an urgent task is to increase the crack resistance of joints with tension during its assembly. The paper examines the influence of the geometry of the spanning part on the process of cracking. To assess the effect of defects on the crack formation, the method of modeling defects with a surface crack of a semi elliptical shape was used. The crack resistance is estimated using the force criterion of fracture mechanics – the stress intensity coefficient. As a result, it was found that the ratio between the wall thickness of the enclosing sleeve and its outer diameter has a significant effect on the crack resistance of the joint with tension, which allows reducing the origin probability and crack development during its pressing by varying these parameters. While assembling joints, the following methods are often used: mechanical-using a press and thermal with heating of the covering part. When the method of joint with cooling of the covered part, the greatest strength of the joint is achieved, but the probability of cracking increases. This is because when the temperature of the enclosing sleeve decreases in contact with the cooled shaft, the critical stress intensity coefficient (fracture toughness), which is a mechanical characteristic of crack resistance, decreases. To reduce the effect of cooling the sleeve, you can use a combined method of assembling the joint, in which the covered part is cooled and the covering part is heated. It is shown that to assess the fracture resistance at low temperatures, it is optimal to conduct full-scale tests, where the cooling and heating temperatures of the press joint parts are the experimental factors.

Two models of hollow core slabs were tested: reinforced concrete and steel fiber concrete. When designing slab models, the proportions of full-sized structures were preserved for the further possibility of correct data comparison. As a result of testing models of hollow core slabs, it was found that the bearing capacity of a slab with combined reinforcement is 24% higher than that of reinforced concrete, the deflection is 36% less, and the crack resistance is 18% higher. The use of steel fiber made it possible to avoid the brittle fracture of a steel fiber reinforced concrete slab, which was observed in the model of a conventional reinforced concrete slab.

The sustainable development of industry and society requires new approaches to the building structures design. The article presents the indices of strength, crack resistance and width of crack opening obtained as a result of experimental testing of beams with hybrid reinforcement with basalt plastic and metal armature. The following beams were examined for comparison purposes: the ferroconcrete beams of the control-series, and the twin beams reinforced only with basalt-plastic reinforcement. It was found that the replacement of the metal armature with basalt plastics led to an increase in strength, on average, by 40%. Similar strength indices were obtained for hybrid reinforcement beams. Crack resistance indices of hybrid reinforcement beams were found to be close to ferroconcrete beams of the control series. Crack resistance indices for these beams were also by 84... 89% higher in comparison with beams reinforced with basalt-plastics. The width of crack openings in hybrid reinforced beams did not exceed the maximum permissible norms at the operational level of loads (70% of destructive) and were smaller than in beams reinforced with basalt plastic reinforcement. Hybrid reinforcement efficiency has been established to improve the performance criteria of beams reinforced with composite armature.

The influence of microstructure parameters and chemical composition on the fracture toughness of steel is investigated. It is shown that the crack resistance of steel can not be reliably estimated only by a single parameter of the microstructure or only by chemical composition. A generalized parameter of microstructure and chemical composition, which correlates well with crack resistance, is proposed.

The authors present the experience of applying their methodology for calculating the residual life of metal structures of reloading machines by the criterion of the development of fatigue cracks to a critical size. The methodology is based on the well-known calculated dependencies of fracture mechanics, refined and supplemented with elements that take into account the specifics of the operation of transshipment machines in difficult weather conditions. Particular attention was paid to the accuracy of determining the stresses in the metalwork element when performing working operations because of the ever changing of the load acting on the metalwork, depending on the weight of the lifted load and the position of the machine in space. To confirm the high sensitivity to the accuracy of the determination of stresses, the dependence of the influence of the resource element metal with a crack from the amplitude of stress is graphically presented. The methodology for assessing the residual resource has been successfully tested on a number of complex metal.

The high water demand of finishing compositions obtained using expanded perlite and vermiculite sand reduces the crack resistance of the resulting thermal insulation coatings. The use of microspheres as fillers should make it possible to increase the crack resistance of the resulting coatings. The crack resistance of lime heat-insulating coatings for the finishing of aerated concrete obtained using ash microspheres of aluminosilicate and expanded vermiculite sand has been determined. It is established, that coatings obtained using aluminosilicate ash microspheres, are characterized by good crack resistance due to low shrinkage deformations, high ultimate tensile properties and uniform distribution of moisture content in the process of moistening.

In order to research on the influence of the height of the fiber reinforcement zone on the normal sections crack resistance, we produced and tested rubcon beams of rectangular cross section with mixed reinforcement; our studies showed that the height of the fiber reinforcement zone has a similar effect on the normal sections crack resistance with the percentage of longitudinal reinforcement. It is important to note that the arrangement of fiber reinforcement at 3/4 of the section height greatly complicates the process of manufacturing the beam while not increasing the strength of the tensile zone compared to the beams with the location of the fiber over the entire height of the section.

The article discusses the methodology for the reinforced concrete structures’ probabilistic deformation calculation. The uniform deformation criteria for assessing the reliability of reinforced concrete structures in the operation stage for strength, stiffness and crack opening are proposed. Taking into consideration the relatively high degree of heterogeneity of reinforced concrete as a building material, each criterion is determined with a predetermined provision.

In this article is described a problem of increasing crack resistance of aerated cement concrete. Authors, having a model of concrete’s structure, made a disclosure of ratios for calculation of parameters the aerated concrete with disperse reinforcement. These ratios show data about change of structure parameters of aerated concretes with disperse reinforcement such as different density by variation of factors water-cement ratio, percent of reinforcement, ratio between dosing of cement and sand. Concrete’s cracking resistance was evaluated by compressive strength and parameter KIc. As result of experimental data processing authors got regression’s equations, which adequately describe changes of fracture toughness and compressive strength of aerated cement concrete (foam concrete) with density 1200 kg/m3 and 1400 kg/m3 in limits of factor area. There was shown a possibility of two-time increasing of fracture toughness and strength of aerated cement concrete with disperse reinforcement its structure by rough basalt fiber.

Ensuring effective operation of structures in zones of aggressive media is associated with the task of studying, obtaining and developing composites of increased chemical resistance, strength and crack resistance. Structures based on corrosion-resistant materials (particularly polymer concretes) play a large role in solving these problems. One of these polymer concretes is rubber concrete or abbreviated as rubcon. This article is devoted to the study of the resistance of the external load to rubber concrete beams of a T-section. As a result of the experiments carried out on three series of rubber concrete T-beams with a different amount of longitudinal reinforcement, quantitative characteristics of the strength and crack resistance of their normal sections were obtained.

The investigations carried out in the field of creation of large-size crack-resistant structures and cellular concrete products have shown that this problem is multifaceted and it must be solved in a complex manner, and one of the ways to increase the crack resistance and durability of such structures and products is prestressed reinforcement.

The article describes experimental research of bending rubber fiber concrete elements with favorable deformation-strength characteristics. The use of such a material as fiberrubcon in load-bearing structures due to its high strength leads to a decrease in material consumption and weight of structures.

Crack resistance of welded joints is one of the most important indices of service reliability of critical designation structures. The purpose of the research is the establishment of the influence of technological modes, hybrid laser-arc welding of high strength steel NA-XTRA-70 on the formation of structure in the metal welded joints, as well as analysis of the influence of this structure on their crack resistances. For the experiments the laboratory setup has been developed on which the experiments were carried out in the technological scheme that provides the location of the consumable electrode arc at a certain distance in front of the laser beam in the welding direction. Nd: YAG-laser DY 044 of company ROFIN (Germany) was a laser radiation source. Power for consumable electrode arc was carried out by welding generator PSG-500. Investigations of structural-phase changes in weld metal and HAZ were carried out by means of optical microscopy (optical microscope Versamet-2 and Neophot-32), microhardness was measured using M-400 gage of Leco company at 0.98N loading. Fractographic investigations were carried out by scanning electron microscopy (scanning electron microscope SEM-515 of PHILIPS company, Netherlands) on fractured specimens of welded joints, made as a result of impact bend tests. An analysis of crack resistance of the welded joints was carried out under different conditions of test temperatures. It was based on experimental data, received by a quantitative fractography method. It is shown that metal of a welded joint produced by hybrid laser-arc welding at Vw = 72m/h rate has mainly failure of ductile nature after external loading. This indicates sufficient level of crack resistance and further working capacity under operation conditions.

Fiber reinforced polymer (FRP) bars are widely used in building structures, especially that are exposed to the aggressive environment influence and other special conditions. Nevertheless, due to the low FRP (e.g. glass, basalt, aramid fibers reinforced polymers) bars modulus of elasticity, exceeding crack opening width, as well as deflections can be observed. FRP bars pretensioning is considered as an effective method of its structural performance increasing. Physico-chemical method of the FRP bars pretensioning based on the self-stressing concrete utilizing is an alternative to the mechanical method and in its turn doesn’t need for special devices and anchorage systems as well as qualified personnel. Assessment of the initial stress-strain state obtained during self-stressing concrete expansion stage in the reinforced self-stressed members is presented. Diagram method of the self-stressing parameters verification based on the static loading tests results is presented. Comparison of the initial stress-strain state obtained during concrete expansion stage and predicted by the proposed model, as well as assessment of its influence on the behavior at the static loading stage in cases of the self-stressed reinforced with FRP bars members and traditionally reinforced with steel bars self-stressed members was performed.

The article seals with the study of hard alloy (WC-Co) crack resistance (fracture toughness), depending on the temperature. Three representatives of one-carbide hard alloys (WC 94% Co 6% (fine grain); WC 92%, Co 8%; and WC 85%, Co 15% alloys) were chosen to determine the temperature influence on the stress intensity factor. During the obtained dependences’ analysis, we revealed that the hard alloy maximum performance temperature could be determined by the maximum value of stress intensity factor KIC. The relation between the temperature of hard alloy (WC-Co) maximum crack resistance (fracture toughness) and the temperature of these materials’ maximum performance, is shown here as a result of experimental study of the dependence of impact resistance from temperature. In addition, the hard alloys’ maximum performance temperature determination technique is developed.

Article is dedicated to development of the scientific and technological principles allowing by means of innovative beam and plasma technologies to receive a new class of heterogeneous nanocomposite coatings having the increased cyclic crack resistance and hardness on the conductive and dielectric complex-shaped products. On the basis of the received results the source of metal atoms and beams of high-energy molecules with a rectangular target was developed and new installation for coating deposition is made.

To reduce shrinkage cracks of cement stabilized macadam base and prolong the life span of pavement, layered materials were mixed in cement stabilized macadam to improve its strength properties and crack resistance. In comparison with the blank test, the unconfined compressive strength increases with the addition of layered materials (weighed at 10% of the amount of cement), by 11.6% with palygorskite, 12.7% with kaolin and 8.9% with montmorillonite, respecetively, at the curing age of 28 days; dry-shrinkage coefficient reduces by 28.2% with palygorskite, 19.0% with kaolin and 14.2% with montmorillonite after 48 days, respecetively. Microstructure of cement pastes mixed with layered materials were observed by scanning electronic microscope. The result shows that more fibrous hydration products and a net-like microstructure exist in cement pastes with palygorskite. It may explain the maximum decrease in shrinkage cracks of palygorskite-mixed cement stabilized macadam.

As far as the problems arising in the using of cracking mortar is concerned, a lot of work are done by researchers to improve the performance of cementations material, including adding various fibers into the cement matrix. The crack resistance mechanism of fiber-reinforced cement mortar is studied by scholars through a variety of methods. In this paper, the roles of fiber in fiber reinforced cement-based composite materials and the explanation thereof proposed by domestic and foreign scholars are summarized.

The stress distributions of the related anchorage zones are complicated under the large tonnage anchorage device. The safety and the crack resistance of the anchorage zone which exists due to the usage of are the critical part of the structural design. Do research on the general distribution regularity of stress of anchor-region by using ANSYS and gives the reason of the cracks occurred on web-plate.

In the framework of ultimate state calculation methods the paper presents some propositions for stress-strain state, crack resistance analysis and failure state of reinforced concrete structures with corrosion damage at supports. The work concerns the durability of concrete and reinforced concrete elements with corrosion damage. The theory for reinforced concrete with corrosion damage is presented for plane stress state

Due to the special environment of the tunnel, the paper developed a kind of antiflaming, warm-mix and noise reduction asphalt mixture combined with engineering practice chishui tunnel project in jiangxi province. Asphalt mixture has good performance in low mixing temperature, flame retardant, noise reduction and better performance by using AMP flame-retardant and Evotherm DAT warmed-mix technology. A series of test are carried out to analyze the characteristics of high temperature rutting, low temperature crack resistance and water stability of warmed mix flame retardant noise reduction asphalt mixture and Ordinary hot mix asphalt mixture. The result show that, compared with the pavement performance of ordinary hot mix asphalt mixture AC-13, the new type of asphalt mixture OGFC-13 has good cooling, flame retardant and noise reduction performance.

It was based on laboratory test, in order to study on the high temperature stability, water stability and low-temperature crack resistance of AC-16 reclaiming asphalt mixture with different proportion of old material, this test takes into account 9 kinds of these asphalt mixture. The results show, with the old material blending ratio increased, the high temperature stability of asphalt mixture changed for the better, water stability and low-temperature crack resistance deteriorated. The pavement performance meet the requirements of secondary road or less, when old material content is within 70%. The research results provide reference for the application of reclaiming asphalt mixture.

Cold asphalt mixture can be handled at ambient air temperature and thus is regarded as energy saving, convenient for storage, transportation and construction, and can extend the construction season. However, it is commonly used in preventative maintenance of pavement as slurry seal and Micro-surfacing, not as structural layer due to its inferior performance to Hot Asphalt Mixture (HAM). Therefore, it will produce great economic and social benefit if a new cold mix and cold laid mixture can be developed for newly built road pavement application. Proportion design of AC-13 asphalt mixture using specially developed polymer modified emulsified is carried out and the performance of high temperature, moisture susceptibility, and low-temperature crack resistance are evaluated according to HAM technical specification. The results show that each performance of the AC-13 modified emulsified asphalt mixture can meet the specification requirements, and especially perform very well in rutting resistance performance.

It is feasible to polymerize SMPU from MDI, PBA, BDO and DMF. Each component has a good ductility, but there are insufficient in terms of strength, glass-point temperature, crack resistance and implosion tendencies. The formulation (PBA: BDO: MDI: DMF=1: 3: (3-4): (7-8)) is recommended. SMPU polymerized by this proportion has good comprehensive properties. The effect of the two-step prepolymerization method, especially the full polymerization method is satisfactory. The composite Materials obtained from powders and particles by hot press molding and that formed by cotton fabric have good ductility. Finally, some suggestions are proposed about implosion preventing, casting crack preventing and development technology.

A series of laboratory tests on warm-mix AC-13 dense gradation asphalt mixture with 3% EC120 were carried out by the method of identical volume. A comparative analysis of common hot asphalt mixture was performed. The results indicate that the reduction of compaction temperature of warm-mix modified bitumen mixture is 27.1°C with addition of 3% EC120. The road performances of warm-mix asphalt mixture determined by the method of identical volume satisfied the specification. Compared to the common hot asphalt mixture, the warm-mix modified asphalt mixture has excellent high temperature stability, slightly low moisture susceptibility and better low-temperature crack resistance.

In this paper, an indoor large scale model test on the crack resistance of hydraulic tunnel structure which has first adopted the real water load in China was conducted in Dalian University of Technology. The model test can reveal the load carrying capacity and the deformation of the lining structure effectively. Based on the test results, models respectively for the mean crack width and the mean stress of reinforcing bars were developed and then compared with existing monitoring data provided by a hydroelectric station. The results shows that the model for predicting the crack width of lining structure has a good accuracy and thus is of great value in the engineering application.

Presented are the results of investigations of peculiarities of structure formation and phase composition in a metal of laser-welded joints from high-strength steel 14KhGN2MDAFB. The analytical evaluations of strengthening along a welding zone and crack nucleation stresses in the places of stress concentrators determined using the experimental data that a structure being formed provides for uniform level of mechanical properties and crack resistance of the welded joints.

In order to deeply analyze the feasibility of the application of building demolition waste on asphalt concrete, pavement performance of asphalt concrete using different content of building demolition waste was analyzed. Results show that: (1) the addition of building demolition waste increases the asphalt-aggregate ratio of asphalt concrete, and the asphalt-aggregate ratio increases 0.25% with the 10% increase of building demolition waste content; (2) the high-temperature stability of asphalt concrete improved significantly with the increase of building demolition waste content; (3) building demolition waste can improve the low-temperature crack resistance of asphalt concrete, and the optimum content is 30%~40%.

The paper describes the crack initiation in the layers which were applied by laser surface cladding. The paper investigates the influence of the chemical composition of layer materials and welding technology on the tendency of the crack formation. Proposed method can dramatically reduce the formation of surface cracks in the applied layers.

Selection of mechanical equipment is realized in the technical study on site. And according to different device powers and flow, relevant piping connections are perfected; then according to proportion of foaming agent developed in the lab, at the scene foaming equipment with compressed air is used to prepare foaming agent with good stability; then according to construction process, different dosage of early-strength admixture effecting the performance of compressive resistence of inorganic solidification foam materials in different time; at last, after the equipment being debugged well and relevant materials being prepared, inorganic solidification foam prepared to be 900 kg/m3 in the experiment is injected into baffle made from wood for solidifying; after 7 days, the dam constructed by this technology is detected with the result that there exists no apparent air leakage, forming a light closed-cell structure. The dam has a good performance of crack resistance and prevent air leakage.

In this paper, Superpave analysis system is adopted to determine the mix proportion of asphalt mixture. Performance tests were carried out on this basis. The results show that there is an improper content range of fine aggregate to improve the high temperature stability of asphalt mixture. But the more fine aggregate content, the better low-temperature crack resistance stability.

Aimed at the question of excessive tension stress in local area in concrete structure, a ribbed steel plate-concrete composite structure (RSPC) which can improve crack resistance and prevent crack developing was proposed. Four specimens of RSPC flexural members were designed to be compared with common concrete flexural members. The test results show that RSPC, which cracks appeared in upper limb, have much more crack resistance ability than common concrete flexural members. According to energy absorption principle in failure process of composite materials, the crack mechanism of RSPC composite structure was studied.

The establishment of pillars is one of the most effective methods to keep mining safety under loose aquifer. Water abundance of bottom aquifer of loose strata,strength and structure of overburden strata are the main factors controlling type and height of coal pillar.Taking Xiyi area in Pansan coal mine as an example, hydrogeology characteristics of the bottom aquifer of quaternaty system and engineering geological properties of overburden strata of No.8 seam were analyzed.The characteristics of weathered rock was particularly analyzed.The results indicated that the type of the water abundance and permeability in this aquifer were medium.When the No.8 seam in Xiyi area was at shallow depths mining, water-proof pillar had to be designed.The structure of overburden strata of No.8 seam belonged to the type of upper soft and lower hard,which can restrain the failure of overburden strata.The thickness of weathering zone was thick and distribution was also stable.Weathered rock had good water-resisting property and crack resistance.

The X ray computed tomography (X-CT) was applied to test the cracking resistance of cement paste, and the hydration process was monitored to study the effect of fly ash on the early age cracking performance. The results showed that the hydration heat reduced with the increase of fly ash under the same water-cement ratio. Within 24h, the porosity increased with time. The addition of fly ash increased the proportion of large holes and then changed the internal stress state. Using X-CT test method and by comparing the number of cracks, the sample with 20% FA was found to have the most serious cracks, whereas the sample with 30% FA had the best crack resistance.

In order to explore performance and economic benefits of the most commonly used fiber asphalt mixture, four types of fiber asphalt mixture were studied in this paper through a series of capability tests, such as water stability, high stability, low temperature crack resistance and fatigue stability test. Based on dynamic stability, low temperature bending strain, freeze-thaw splitting strength ratio, fatigue life and cost per square meter as the evaluation index, Grey Relational Analysis (GRA) was proposed in this study to determine the best performance and economic benefits of fiber asphalt mixture. The results show that Fiber B asphalt mixture only has better anti-cracking performance in low temperature and fatigue life,but fiber C asphalt mixture has better performance and economy than the other three fiber asphalt mixtures under the same conditions with grey relational analysis.

Use polyurethane rubber composite modified asphalt.Through the Marshall test and rutting test, test of polyurethane rubber asphalt mixture high temperature stability, low temperature crack resistance and water damage resistance, verify the composite modification advantages.

Usually, foamed asphalt as cold recycling mixture binder, study on foamed asphalt warm mix technology was limited in China. Aimed at the asphalt foaming characteristic, the paper put forward the best asphalt foaming condition and carried out indoor and outdoor experiment to study the road performance of warm mixed asphalt mixture. The paper proposed the maturation curing time concept and its evaluation method. Results indicated that the warm mixed asphalt mixtures road performance can meet the HMA specification requirement in a lower temperature of construction, and low-temperature crack resistance was better than the tradition hot mix asphalt mixture so the warm mix foamed mixture has a remarkable economic and society benefit.

Thermal stress is a major cause of early-age crack of massive concrete structures. In order to analyze the influencing factors of concrete crack under thermal loads, a series of tests were conducted using the improved Temperature Stress Testing Machine (TSTM). Effects of temperature on crack resistance of concrete were studied on different concrete placing temperatures and curing temperatures. Meanwhile, the roles of reinforcement on concrete crack resistance and crack-width limitation were quantitative analyzed, which compare cracks of plain concrete and reinforced concrete with the same mix proportion. The results indicate that reinforcement can improve the crack resistance of the structures by approximately twenty percents, which against the engineering experience. After concrete cracks, the cracks photos show that reinforcement can induce the smaller cracks formation, and the crack width of reinforced concrete is about 1/10 of the plain concrete crack width.

Anti-rut agent, named RPS-3000,was added into AC-25 asphalt mixture and its effects on high temperature stability, low temperature cracking resistance, water damage resistance and fatigue life were investigated in this paper. Results showed that the high temperature stability and low temperature crack resistance of the asphalt mixture improved significantly, the water damage stability increase slightly due to the introduction of anti-rut agents. Besides, the result of fatigue life test presented that excess amount of anti-rut agent may lead a deterioration of fatigue life. Keywords: Anti-rut agent; High temperature stability; Asphalt mixture

In order to investigate the influence of surface modification on concrete comprehensive properties, special electrodeposition process is applied to modify the surface of steel fiber. Then the modified fiber and the non-modified fiber are added into concrete for comparisive test and analysis. The results illustrate that the bond strength between the modified fiber and concrete increases about 50% when competing with the non-modified group. Besides, the crack area of non-modified fiber group declines 46% and the toughening effect rises approximately 30%.

In order to solve the serious question of early cracking of concrete in drying environment in the western of china. Using the same volume steel slag substituting fine aggregate (coarse aggregate) to mixing concrete with its porous characteristics, which are carried out by the knife-edge method. The result shows that: the compressive strength of steel slag concrete is better than the blank group at 7d and 28d ages;The Water holding capacity, the time of early cracking of concrete is delayed, the width and area of crack is significantly reduced with the increase of steel slag in same water-cement ratio. Simultaneously, the water retention and the crack resistance of concrete using steel slag stone is better than concrete using steel slag sand in same dosage. The porous steel slag can improve the internal relative humidity of concrete, restrain the early shrinkage of steel slag concrete, and help to improve early cracking resistance of concrete from the view of internal curing.

The superstructure of H-bridge is prestressed concrete composite box-girder with corrugated steel webs with a main span of 90m, and the span arrangement is 52m+90m+52m. In this paper, the finite element method is used to model H-bridges superstructure and do analysis of construction stage and completed bridge stage, and the analysis is checked with the current corresponding regulatory of bridge design and construction. Checking results show that under the existing highway-level loads, the main beams carrying capacity, stress, crack resistance, deformation and corrugated steel webs shear strength and shear stability meet the regulatory requirements. The checking process also reflects the mechanical properties of corrugated steel web.

After thin layer repaired, airport pavement will still appear crack, this situation not only spend a lot of maintenance costs, and seriously affect the use. This paper made flat constraint test for concrete containing poly carboxylic acid by using reinforced constraint plate mold, then the KON-FK(O) crack width tester and KON-FSY crack depth tester has been used in measuring on the surface of a block. Through the measured data analysis, crack effect is best when poly carboxylic acid with percentage of 2% and 2%.

In order to comparatively study the effect of warm mix modifiers on the road performance of guss asphalt, the guss asphalt mixtures, whose asphalt aggregate ratio were 8.5%,9.0%,9.5% respectively, were mixed with 0%,1%,2%,3% of the RH and Sasobit warm mix modifiers. Then by means of Lueer test, penetration test, wheel track test and low-temperature bending test, the performance of guss asphalt were evaluated. The test results show that: RH and Sasobit can effectively improve the workability of guss asphalt; RH is better than Sasobit in reducing viscosity of guss asphalt; RH reduces the high-temperature properties of guss asphalt; On the contrary, Sasobit can improve the hightemperature performance of guss asphalt; RH and Sasobit have an adverse impact on the crack resistance of guss asphalt in low temperature, so their content should not too high. Guss asphalt has characteristics of high construction temperature and energy consumption. In order to reduce construction temperature, based on energy conservation, low-carbon emission environment, reduce the aging of asphalt principle, warm modifiers could be used to reduce the viscosity of guss asphalt at high temperatures[1-5]. Sasobit modifiers imported from Germany are used much more to improve the workability of guss asphalt. In this paper, 0%, 1%, 2%, 3% RH and Sasobit warm mix modifier were mixed with the aggregate ratio of 8.5%, 9.0%, and 9.5% of the Guss asphalt to compare and analyzed the performance of those two warm modifiers on Guss asphalt.