Advanced Materials Research Vols. 250-253

Abstract: Based on the analysis of the chemical structure of polycarboxylate-type SPs grafted PEO side chains, as well as sulfonic and carboxylic acid groups, a kind of polycarboxylate-based SPs grafted varied PEO side chains were synthesized by using radical polymerisation techniques.The relative dispersing effectiveness of the SPs was evaluated in cement paste and concrete by measuring paste flow and concrete slumps. The test results indicat that the copolymers with shorter PEO side chains (with 9 and 14 EO units) give lower initial dispersing power but higher time retention,with the prolonging of PEO side chains the higher initial dispersing effect and the lower time retention can be received. The excellent dispersing property and time retention of synthesized SPs for cementious systems can be achieved by grafted long side chain(with 45 EO units) integrated with short side chain(9 or 14 EO) at the backbone of anionic polymer.

Abstract: The effects of cement clinker on the properties of flue gas desulphurization gypsum-based steel slag composites were analyzed in this article and the influence rules of setting time, final setting time, flexural strength and compressive strength of cementitious composites were also discussed. The micro-morphology of the composite was observed by scanning electron microscope. At the same time, the excitation mechanism of cement clinker on gas desulphurization gypsum-based steel slag was put forward. It was demonstrated that cement clinker with content of 2% in the composites can better stimulate the activation of steel slag and improve the mechanical properties of the composites.

Abstract: The test confects C20, C25, C30, C35 and C40 recycled aggregate concrete, and the percentage of recycled aggregate are 0%, 20%, 30%, 50%, 70% and 100%,the test age of sample are 7d,28d and 56d.Through test, the cube crushing strength,prismatical compressive strength and elasticity modulus of recycled aggregate concrete with different recycled aggregate percentage and different ages are studied, and compare with general concrete. Test show that, with the development of age, the strength development law of recycled aggregate concrete is similar to general concrete; with the increase of amount of recycled aggregate, the strength and elasticity modulus of recycled aggregate concrete shows the trend of decline, and the basic mechanic property of recycled concrete meet the demand of existing criterion.

Abstract: Evaluation indexes system has been put forward in this paper for quantifying the systematical energy consumption, resources consumption, total emissions’ change and waste disposal capacity in road construction with recycled waste materials involved. With help of this evaluation indexes system, the contributions to environmental improvement caused by recycling waste materials in road construction can be quantified through calculating savings on environmental impact potentials, savings on energy consumption, on virgin materials’ consumption and waste disposal capacity provided by road construction. Based on the construction project of a road section numbered No.20 EWK0+400 ~ EWK0+600 of North highway to Shanghai Pudong international airport, which was the first trial project of using several kinds of recycled waste materials including bottom ash from incinerators to replace commonly used materials such as gravel in large scale in road pavement, the results of the four indexes, namely, savings on energy consumption and virgin materials’ consumption, environmental impact potentials as well as waste disposal capacity were obtained. It was found out that with multi recycled waste materials replacing part of the common construction material, systematical energy consumption can be reduced by 30%, a large amount of virgin resource consumption can be avoid and road construction also provides a remarkable large “dumping site” for solid wastes; while at the same time environmental impact potentials were saved for most impact categories except for increase in Ecotoxicity, water chronic, which was caused by heavy metals’ leaching and can be prevented by pre-treatment. Those results are useful for guiding the utilization of recycled waste materials, as well as for developing new technology process and advanced materials in road construction.

Abstract: We use the bottom ash from Harbin Municipal Solid Waste Incineration Plant as concrete coarse aggregate and study the engineering properties of the coarse aggregate, failure mode of waste incineration bottom ash concrete, the relationship between compressive strength and bottom ash coarse aggregate replacement rate, water cement ratio, apparent density and development trend of compressive strength. Comparing with natural aggregates, the bottom ash has higher water absorption rate, lower apparent density and crushing value index. The failure mode of waste incineration bottom ash concrete is similar to ordinary concrete and the flat and elongated particles have effect on compressive strength. Bottom ash coarse aggregate replacement rate has different effects on compressive strength in different water cement ratio. Compressive strength of waste incineration bottom ash concrete has the same development trend with ordinary concrete. Compressive strength and apparent density has a linear relation.

Abstract: Modified lignin cement water-reducer was prepared via hydroxymethylation followed sulfonation of wheat straw ethanol lignin. The optimum process conditions of sulfonation of wheat straw ethanol lignin were mainly investigated. Fourier transform infrared spectroscopy (FT-IR) was performed to characterize the chemical structure of mofified ethanol lignin. Its morphology was revealed by the scanning electron microscopy (SEM) observation. The application results showed that when the modified lignin dosage was 0.5% the fluidity of cement paste reached 208mm, water-reducing ratio was 14.9% which was 30.7% higher than using commercial Sodium Lignosulfonate; and with the addition of modified ethanol lignin, the 3 and 7 d compressive strengths of concrete are13.8 % and 9.9 % higher than using commercial Sodium Lignosulfonate respectively.

Abstract: Effect of iron ore tailings as fine aggregate on pore structure of mortars has been studied in this paper. The purpose is to investigate, as fine aggregate, comparing to natural sand, whether the iron ore tailings can improve the pore structures of mortars or not. Pore structure parameters were measured with the instrument of MIP and calculated with corollary software. The pore structure parameters from four kinds of mortars with different fine aggregates are compared with each other. This paper will provide more data about the use of this artificial aggregate, which may increase the feasibility of the use of this by-product in the mortar or cement concrete industry.

Abstract: This paper investigates the feasibility of using the P-wave velocity measured by the impact-echo technique to estimate the strength of hardened self-consolidating concrete. The relationship between the through-transmission ultrasonic pulse velocity (UPV) and the strength of high performance concrete was established previously by performing experimental studies on water-cured cylinders made of concrete having variations in water-cementitious amterial ratio and aggregate content. However, the through-transmission UPV measurement is not applicable to concrete elements with only one accessible surface. In this paper, two plate-like specimens were made of self-consolidating concrete and they had different curing conditions. One specimen was immersed in water and the other was covered with wet gunny sack for 7 days. The impact-echo technique, one-sided wave velocity measurement technique, is adopted to determine the P-wave velocity of the plate-like concrete specimens at an age of 28 days. The difference between the impact-echo P-wave velocity (IE-PV) and the through-transmission ultrasonic pulse velocity (UPV) is studied. In addition, the measured IE-PV is used to estimate the strength of the plate-like concrete specimen and the estimated strength is verified by taking cores from the specimen.

Abstract: The influence of fly ash as cement replacement on pore structure, chloride penetration and frost resistance of recycled concrete is investigated by evaporable water test, chloride natural diffusion test, and freeze-thawing test. The experimental results indicate that adding fly ash to recycled concrete can decrease its porosity and improve its pore size distribution. Chloride penetration resistance of recycled concrete is enhanced firstly and then reduced with increasing of fly ash content. The best proportion replacing cement with fly ash is 20%. Fly ash content has a certain influence on the frost resistance of recycled concrete, and the frost resistance of recycled concrete only has been improved when the proportion of fly ash replacing cement achieves more than 20%.

Abstract: The application of cold-formed steel in light steel framing design can become a popular choice of Industrialized Building System, by moving huge amount of construction work to the factory and leaving the construction site cleaner and safer. However the joints behaviour for primary structures, particularly the partial strength semi-rigid beam-to-column connection has not been studied in depth. This paper presents the isolated joint test on slip-in connection using 6 mm hot-rolled steel gusset plate. Two cold-formed lipped channel sections were placed back-to-back to form beam and column members. Three specimens with the depth of beam ranging from 150 mm to 250 mm were tested. From the experimental results, it is observed that the ratio of moment resistance of joint to the moment resistance of the connected beam increases in the range of 0.46 to 0.70. The rotational capacities of the joints exceed 30 mRad. The rotational stiffness achieves 511 kNm/rad to 1671 kNm/rad. It is concluded that the proposed connections could be classified as partial strength connection.