Search

The viscosity-reducing polycarboxylic acid superplasticizer PCZ-100 was synthesized from the copolymerization of methacrylate block polyether (JHE-220), acrylic acid (AA) and sodium methylallyl sulfonate (SMAS). The effects of monomer molar ratio, reaction temperature, amount of chain transfer agent and amount of initiator on the properties of superplasticizer were studied, and the effects of different ratios of viscose-reducing carboxylic acid and water-reducing carboxylic acid on the properties of concrete were tested. The results show that the optimum synthesis conditions of PCZ-100 are as follows: n (JHE-220) :n (AA) :n (SMAS)=1.0:3.5:0.3, the amount of chain transfer agent was 1.7% of the total weight of monomer, the amount of initiator was 1.2% of the total weight of monomer, the reaction temperature is 65~70 °C. The superplasticizer synthesized by the above formula and process can better reduce the viscosity of concrete and obviously improve the strength of concrete. [ABSTRACT FROM AUTHOR]

Using epoxy resin and polyol diluents as base materials, adding appropriate curing agents and fillers, an epoxy resin mortar for rapid repair and reinforcement of solventless concrete was prepared. The effects of the amount of diluent, the type and amount of filler on the properties of epoxy mortar were studied. The results show that when the dosage of diluent is 20%, the dosage of cement is 27%, the dosage of thickener is 3%, the dosage of standard sand is 35% and the dosage of slag is 14%, the 3-day test compressive strength reaches more than 80% of the 28-day compressive strength, which can be used for rapid repair of concrete engineering. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to explore the repair characteristics of polymer modified silica powder mortar, an experimental study was conducted on the compressive, splitting and tensile properties of mortar mixed with acrylic emulsion (10%, 20% and 30%) and silica powder (5% and 10%) and its direct tensile bonding and bending bonding properties so as to provide a basis for the application of high-performance repair materials on concrete surface. The results show that, the addition of acrylic emulsion and silica powder can effectively improve the compressive strength and splitting tensile strength of mortar. When the addition of acrylic emulsion is 30% and the addition of silica powder is 10%, the compressive strength and splitting tensile strength of specimens at 28 d are increased by 15.24% and 46.90% respectively when compared with control samples. The addition of silicone powder and acrylic emulsion can effectively improve the bonding strength of mortar. The direct tensile bonding strength and flexural bonding strength of repair mortar using acrylic emulsion as the binder can reach 3.3-4.2 MPa and 7.5-11.4MPa,respectively. Acrylic emulsion modified silica mortar has excellent tensile and bonding properties and can be used as an ideal repair material for concrete, especially hydraulic concrete. [ABSTRACT FROM AUTHOR]

With the construction of underground subways and tunnels in major cities, large volume concrete is more and more widely used, and the release of a large amount of heat of hydration generated by its pouring is more concentrated. The application results in cracks arising from the large temperature difference between the inside and outside of concrete, which affects the safety of the structure and normal use. As a new type of concrete admixture, glassy fly ash beads have the advantages of high activity, light weight, corrosion resistance, wear resistance, high compressive strength and good thermal stability. Adding them to concrete can improve the pore structure of concrete and increase the crack resistance and compactness of concrete. The effects of different dosing of glassy fly ash beads on the compressive strength and splitting tensile strength of C20, C30 and C40 concrete and the heat of hydration were studied. The test shows that the content of glass fly ash microbeads for C20 concrete should be controlled at about 10%, for C30 concrete should be controlled at about 15%, and the content of glass fly ash microbeads for C40 concrete should not exceed 10%, resulting in better concrete quality. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new type of high activity EPEG monomer was selected to react with acrylic acid, hydroxyethyl ester and other small monomers. The optimal process for synthesizing anti mud and slump retention polycarboxylate superplasticizer was determined through orthogonal experiment and single factor influence experiments as follows: Acid-ether ratio 2.0, ester-ether ratio 2.6, dropping time material A 40 min, material B 50min, reaction process without temperature control, primer concentration 60%, reducing agent dosage 0.23%, chain transfer agent dosage 0.69%, terminating phosphate ester dosage 4.30%. The test results of cement paste and concrete show that the synthesized polycarboxylate superplasticizer has good dispersibility and slump retention, and has no adverse effect on the strength of concrete. [ABSTRACT FROM AUTHOR]

The ultrafine composite mineral admixture (HP-UA) of fly ash-mineral powder was prepared by grinding treatment. The effects of 15%, 25% and 35% dosage on concrete mechanical properties, durability were studied. It used scanning electron microscope and X-ray diffractometer to analyze the mechanism of its effect on concrete properties. The results show that the addition of HP-UA is beneficial to the improvement of concrete mechanical properties, shrinkage resistance, water penetration resistance, chloride ion penetration resistance, sulfate corrosion resistance. It had a two-sided effect on the carbonation resistance of concrete. The particles of HP-UA had fewer apparent defects. HP-UA formed better particle gradation with cement. Its hydration produced more calcium silicate hydrate and C-S-H gel. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of how to regulate the expansion effect of MgO expansive concrete, the time-dependant effects of reinforcement ratio, reinforcement stress and curing method on the limited expansion rate of MgO expansive concrete were studied, the shrinkage compensation characteristics of MgO expansive concrete were analyzed, and the regulation measures of MgO expansive concrete were put forward. The results show that with the increase of reinforcement ratio, the limiting expansion rate and the limiting expansion rate growth rate of MgO expansive concrete show a downward trend. When the reinforcement ratio exceeds 1.54%, it would significantly inhibit the expansion effect of MgO expansive concrete. When the tensile stress of reinforcement is less than 20%, the influence of reinforcement stress on the expansion effect of MgO expansive concrete is not obvious. Polymer film covering curing can effectively promote the expansion effect of MgO concrete in the early stage, but the expansion promoting effect in the later stage is lower than the standard curing method. [ABSTRACT FROM AUTHOR]

The effects of different forms of silica ash and compounding ratios on the rheological properties and activity index of rubber sand were studied, and the effects of equal amounts of composite admixtures on concrete work and mechanical properties were studied. The results show that when the silica ash compound ratio exceeds 40%, the flow rate decreases. When the compound ratio is 8:2, the two encrypted states of silica fume-fly ash composite doping activity index is the highest, and the semi-encrypted silica ash activity index is higher than that of full encryption. The use of composite admixture can improve the strength performance of concrete while increasing the expandability and improving the adhesion of concrete, but it contributes less to the strength of the long -term age. Comparing the intensity contribution rate of the volcanic ash effect, it was found that the contribution rate of the composite admixture to the ash effect strength of the early and late concrete was low, and the contribution rate of the semi-encrypted silica ash-fly ash admixture to the strength of the concrete volcanic ash effect was higher. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to improve the application performance of pumping concrete, the liquid antifreeze pumping agent was prepared by adding antifreeze, air entraining, retarding and early strength components into water reducing agent. The optimal concentration of each component was determined by 5-factor 4-level orthogonal test design. Analysis of variance (ANOVA) was used to study the low temperature storage stability of antifreeze pumping agent, the slump of concrete, the slump loss value and the technical performance indexes of R-7, R28 and R-7+28. The effect of antifreeze pumping agent on concrete microstructure was dis cussed by scanning electron microscope (SEM). The results show that when the mass fraction of polycarboxylate superplasticizer, sodium gluconate, twelve alkylbenzene sulfonate, calcium nitrate and methanol were 25%, 0.3%, 0.5%, 11% and 9% respectively, their low temperature frost resistance, initial slump, loss of time slump and low temperature compressive strength were better. The C-S-H gel was connected and packed early in the tested concrete with antifreeze pumping agent And the internal pores of concrete was filled and the microstructure was compact. [ABSTRACT FROM AUTHOR]

Taking the mass block and unloading-board concrete structure of gravity wharf as the research object, through temperature measurement and contrast test, we have made a research in preventing the cracks of mass concrete structure by using temperature controlling expending agent. Through exploring its control ability in temperature and cracks preventment of mass concrete, we have come up with the optimal dose of HST-A2 temperature controlling expending agent in normal mass concrete construction condition and key technical measures to be taken in construction. The goal of eliminating the mass concrete cracks has achieved basically. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)