Advanced Materials Research Vols. 941-944

Abstract: The cementitiousness between rubber particles and cement-based material could be raised because of the surface modification of rubber,thus enhance the mechanical property of crumb rubber concrete and improve the interface effect of rubber particles.We had researched the change regulation about the ratio of bending-compressive strength of the crumb rubber concrete modified by latex,the concrete with various quantity of rubber,under the condition dosage of latex is 0.5% of cement quality.The result of experimental prove that,compressive strength, splitting tensile and flexural strength could be enhanced because of latex injecting,and the ratio of bending-compressive strength could be enhanced at the same time.

Abstract: The plastic ultimate moment of concrete-filled steel tubular and the ultimate displacement of the simply supported beam under uniformly distributed load is established based on unified strength theory. Considered nonlinear impact of mass and stiffness changed in the process of the reaction, the dynamic response of concrete-filled steel tubular columns under blast load were analyzed by the equivalent single degree of freedom model and step by step integration method. Compared the results of this method with relevant literatures, the consequence is good. It can be seen that from the results, this method was satisfied for the requirement of the analytical precision, it can be referred for the research and the safety of concrete-filled steel tubular columns under blast load.

Abstract: Aiming at the specific concrete filled square steel tubular short column stiffened with PBL under axial compression load, considering about the useful effect of the PBL shear connectors, the mechanical behavior of PBL stiffening ribs was analyzed. Through the analysis of the effective restriction-area and ineffective restriction-area of core-concrete, introduce into the effective constraint coefficient of concrete. The ultimate bearing capacity was deduced based on the unified strength theory, with some influencing factors analyzed as well. Compared with the test results in relevant documents, they coincided well with each other. The result shows that the formula which is deducted from the unified strength theory has good applicability and the solution will show its positive impact in the related fields.

Abstract: Aggregate characteristics of shape, texture and grading influence on workability, finishability, bleeding, pumpability and segregation of fresh concrete and affects the strength, shrinkage, density, and durability of hardened concrete. About 80% of total volume of concrete consists of aggregate. Construction and durability problems have been reported due to poor mixture proportioning and variation on grading. Aggregate characteristics significantly affect the performance of Quality Concrete (QC) both in fresh and hardened state and have an impact on the cost effectiveness. Flaky and elongated particles lead to higher voids than cubical, rounded and well graded particles. The shape factor of aggregate plays a vital role in the design and performance of QC mix and it is mainly depends on the rock formation and type of crusher being used for crushing the aggregates. Flaky and elongated particles have larger specific surface area which results in higher demand of cement paste in cement concrete mix. These particles impede compaction or break during rolling and decrease the strength of the concrete structures. An attempt is made to study the effect of shape of aggregate on quality of the concrete used for the buildings and pavements. Initially an aggregate samples were collected from the stone crusher (two types) and prepared with different proportions of Flakiness and Elongation indices to conduct tests on properties of aggregates and compressive strength and flexural strength tests on concrete. The effect of different percentages from 0 to 50% of combined Flaky and Elongation Aggregates (CFEA) for quality concrete on the compressive and flexural strength of cement concrete is studied. The other properties of aggregate such as bulk density, impact value, water absorption have been studied for different shapes of aggregates. The cost analysis has been carried out with an optimum value of 30% CFEA in 1:3 proportions of flaky and elongated particles.

Abstract: In the process designing of concrete arise the problem - compatibility polycarboxylates with cement different parties. In some cases, when you receive the next batch of cement concrete mobility decreased sharply. Additive had to pick again. When choosing supplements examined its effect on the technological properties of concrete mixtures: workability, resistance to water gain, air entrainment. Test results showed that the addition of superplasticizer based on sulfonated naphthalene-formaldehyde resins (SNF) on the effectiveness of the plasticizing action is not inferior hyperplasticizer based polycarboxylate. Unlike polycarboxylates SNF additive has good compatibility with various cements, which provides stability regardless of the characteristics of the concrete mix to the vibrations of the chemical composition of cement. With increasing content of cement in the concrete superplasticizer efficiency increases, both in terms of workability, and in respect water gain of a concrete mixture.

Abstract: This article deals with the strength and thermophysical test results made on the basis of the masonry samples of cellular autoclave curing concrete (aerated concrete blocks) with the use of polyurethane adhesive. Aerated concrete masonry walling with the use of polyurethane adhesive is indicated herein to be technologically feasible and economically viable. The major advantage of the masonry option under consideration lies in the following aspect: thermal conductivity of polyurethane adhesive used to fasten aerated concrete blocks in masonry walls is significantly less than thermal conductivity of concrete adhesives and mortars. For this reason, thermal insulation properties of the masonry with polyurethane adhesive appear to be better comparatively to the block masonry made with the usage of concrete adhesives of any other type. On the ground of the tests conducted the following was resumed: it is acceptable to carry out masonry works with the use of aerated concrete blocks and polyurethane adhesive in construction of exterior and interior nonbearing walls provided appropriate justifying calculations are made.

Abstract: This paper fitted the measured data of surface settlement with the Peck formula on the background of Xi'an metro line 2, modified the trough width parameter K and volume loss η of Peck formula to make it apply to the loess region and provide a reference for future shield subway construction in loess area. The results have shown that the modified settlement trough width parameter K=0.42~0.44, volume loss η should be determined according to the different formation conditions and construction parameters, 0.7%~2.0% is reasonable under normal circumstances.

Abstract: Concrete filled steel tube Support has a good load-bearing capacity, in this paper, shallow arch circular concrete filled steel tube support was designed, two kinds supports of Φ194×8 and Φ168×6 are to experiment according to shallow arch circular steel concrete structures and their load-displacement curves, ultimate bearing capacity and support failure mode are especially tested in experiment.

Abstract: Based on the review of the history of domestic and foreign architecture, the necessity and urgency of industrialization in construction is expounded. According to the current status and problems of the assembled structure in severe cold region, the method is given. The feasibility analysis is done in the light of the comparatively example.

Abstract: The main direction of energy saving in construction is the construction of buildings with high heat-shielding properties walling. In connection with this widespread walling using efficient insulation, allow to increase thermal protection of buildings.