Experimental Research on Seismic Behaviour of Low-Carbon Construction Materials RAC Frame Columns

2011 ◽  
Vol 194-196 ◽  
pp. 1958-1961
Author(s):  
Chao Liu ◽  
Guo Liang Bai ◽  
Hong Jin Zhao
Keyword(s):  
Failure Process ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Low Carbon ◽  
Replacement Rate ◽  
Seismic Behaviour ◽  
Aggregate Concrete ◽  
Ordinary Concrete ◽  
Concrete Frame ◽  
Seismic Behaviors

A comparative study is conducted on the seismic behaviors of three recycled aggregate concrete (RAC) frame columns under low cyclic load. The recycled aggregate replacement rate is 0%, 50%, 100% respectively. The mechanical characteristics, failure mode, hysteresis loops, ductility and consumption characteristics of frame columns with different recycled aggregate replacement rate and same axial compression ratio are analyzed in this paper comparatively. The rule characteristics between ordinary concrete and recycled aggregate concrete frame columns are found. The result indicates that failure process of recycled aggregate concrete frame columns is similar to that of ordinary concrete. The seismic behaviors of recycled aggregate concrete frame columns, including the ductility etc., still meet the related requirements of earthquake-resistance designing. So it is concluded in this paper that the recycled aggregate concrete can be applied in concrete structures. Because of its properties are certain deficiencies, some tectonic measures must be enhanced.

scholarly journals Experimental Study on a Prediction Model of the Shrinkage and Creep of Recycled Aggregate Concrete

2019 ◽  
Vol 9 (20) ◽  
pp. 4322 ◽  
Author(s):  
Lv ◽  
Liu ◽  
Zhu ◽  
Bai ◽  
Qi
Keyword(s):  
Substitution Rate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Creep Model ◽  
Aggregate Concrete ◽  
Ordinary Concrete ◽  
Group I ◽  
Significant Difference ◽  
Shrinkage And Creep ◽  
Group Ii

The significant difference between recycled aggregate and natural aggregate is the content of the attached mortar layer. With the increase of the replacement rate of recycled aggregate, the shrinkage and creep of recycled aggregate concrete is significantly increased. In this paper, 180-day shrinkage and creep tests of recycled aggregate concrete with different water–cement ratios were designed in order to analyze the effect of the substitution rate and water–cement ratio on shrinkage and creep properties. The results show that the shrinkage strain of recycled aggregate concrete with a substitution rate of 50% and 100% at 180 days is 26% and 48% higher than that of ordinary concrete, respectively, and the growth of group II is 22% and 47%, respectively. When the load was 180 days old, the creep coefficient of recycled aggregate concrete with a substitution rate of 50% and 100% in group I increased by 19.6% and 39.6%, respectively compared with ordinary concrete, and group II increased by 23.6% and 44.3%, respectively. Based on the difference of adhering mortar content, the creeping increase coefficient and shrinkage increase coefficient of the attached mortar were proposed, and a shrinkage and creep model of recycled aggregate concrete was established. When compared with the experimental results, the model calculation results met the accuracy requirements.

scholarly journals Discrete Element Mesoscale Modeling of Recycled Lump Concrete under Axial Compression

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3140 ◽  
Author(s):  
Yong Yu ◽  
Bo Wu
Keyword(s):  
Mechanical Properties ◽  
Axial Compression ◽  
Discrete Element ◽  
Relative Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Ordinary Concrete ◽  
Coarse Aggregates ◽  
Spatial Locations

In the past decade, directly reusing large pieces of coarsely crushed concrete (referred to as demolished concrete lumps or DCLs) with fresh concrete in new construction was demonstrated as an efficient technique for the recycling of waste concrete. Previous studies investigated the mechanical properties of recycled lump concrete (RLC) containing different sizes of DCLs; however, for actual application of this kind of concrete, little information is known about the influence of the spatial locations of DCLs and coarse aggregates on the concrete strength. Moreover, the mechanical responses of such a concrete containing various shapes of DCLs are also not well illustrated. To add knowledge related to these topics, two-dimensional mesoscale simulations of RLC containing DCLs under axial compression were performed using the discrete element method. The main variables of interest were the relative strength of the new and old concrete, the distribution of the lumps and other coarse aggregates, and the shape of the lumps. In addition, the differences in compression behavior between RLC and recycled aggregate concrete were also predicted. The numerical results indicate that the influence tendency of the spatial locations of DCLs and coarse aggregate pieces on the compressive stress–strain curves for RLC is similar to that of the locations of coarse aggregates for ordinary concrete. The strength variability of RLC is generally higher than that of ordinary concrete, regardless of the relative strength of the new and old concrete included; however, variability has no monotonic trend with an increase in the lump replacement ratio. The mechanical properties of RLC in compression are little influenced by the geometric shape of DCLs as long as the ratio of the length of their long axis to short axis is smaller than 2.0. The compressive strength and elastic modulus of RLC are always superior to those of recycled aggregate concrete designed with a conventional mixing method.

Test Research on Elastic Modulus and Poisson’s Ratios of Long Age Recycled Aggregate Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 1051-1055 ◽  
Author(s):  
Wei Ning Li ◽  
Dong Hui Zhan ◽  
Jin Jun Xu ◽  
Wen Zhang ◽  
Zong Ping Chen
Keyword(s):  
Elastic Modulus ◽  
Time Effect ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Compression Tests ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Axial Compressive Strength ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

In order to reveal the constitutive behavior of recycled aggregate concrete (RAC) which is related to time effect, 33 prismatic specimens were designed to have uniaxial compression tests. The changing variation of elastic modulus and Poisson’s ratios of RAC specimens which were placed two years in the lab were inspected, and a related correction formula was put forward to describe the elastic modulus. The results show that with the aggregate replacement rate growing, the RAC brittleness was relatively obvious. Since time effect played a great role, the axial compressive strength and elastic modulus were larger than those of normal concrete and the standard age concrete which is calculated. Poisson's ratio did not change significantly and the values were relatively stable, while the higher replacement rate is, the lower values are.

Experimental Study on Compressive Strength of Recycled Aggregate Concrete with Different Replacement Ratios

2012 ◽  
Vol 174-177 ◽  
pp. 1277-1280 ◽  
Author(s):  
Hai Yong Cai ◽  
Min Zhang ◽  
Ling Bo Dang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Failure Mode ◽  
Failure Process ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Replacement Ratio ◽  
Aggregate Concrete

Compressive strengths of recycled aggregate concrete(RAC) with different recycled aggregates(RA) replacement ratios at 7d, 28d, 60d ages are investigated respectively. Failure process and failure mode of RAC are analyzed, influences on compressive strength with same mix ratio and different RA replacement ratios are analyzed, and the reason is investigated in this paper. The experimental results indicate that compressive strength of recycled concrete at 28d age can reach the standard generally, it is feasible to mix concrete with recycled aggregates, compressive strength with 50% replacement ratio is relatively high.

Mechanical Research on Bond-Slip Behaviors of Recycled Aggregate Concrete-Filled Square Steel Tubes

2012 ◽  
Vol 166-169 ◽  
pp. 3233-3236 ◽  
Author(s):  
Jun Tao Li ◽  
Jin Jun Xu ◽  
Zong Ping Chen ◽  
Yi Li ◽  
Ying Liang
Keyword(s):  
Bond Strength ◽  
Concrete Strength ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Steel Tubes ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Ultimate Bond Strength

In order to research the interface bond-slip behaviors of recycled aggregate concrete-filled square steel tube (RACFSST), ten specimens using waste concrete were designed for launch test. The three changing parameters were concrete strength grade, embedded length and recycled coarse aggregate replacement rate. The load–slip curves of square steel tubes and recycled aggregate concrete were obtained, and starting bond strength and ultimate bond strength influenced by each changing parameter were analyzed. The results show that the replacement rate had a slight influence on the starting bond strength and ultimate bond strength, while the embedded length had the opposite effect. The shorter embedded length specimens had larger bond strength. The concrete strength had a relatively large influence on them.

On Construction Wastes Recycling and its Economy

2013 ◽  
Vol 567 ◽  
pp. 119-122
Author(s):  
Yue Qin Tang
Keyword(s):  
High Performance ◽  
Drying Shrinkage ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Bleeding Rate ◽  
Aggregate Concrete ◽  
Ordinary Concrete ◽  
Easy Bleeding ◽  
Large Water ◽  
Water Absorbability

This paper addresses problems of aggregate concrete of construction wastes, which were featured as large water absorption, quick slump loss, as well as easy bleeding and low strength of concrete. A comparative analysis by experiment between recycled aggregate concrete and ordinary concrete was made on aspects of water absorbability, compressive strength, slump loss, bleeding rate, drying shrinkage and economic efficiency. It has found possible to preparing the recycled aggregate concrete of high performance through the prewetting recycled aggregate. It is concluded that construction wastes can be recycled by obtaining the optimum mole of preparing recycled aggregate concrete of construction wastes and evaluating their reliability on cost-lefficiency and mechanic capability，thus, it also recycled the limited resources and solve some environment problems.

scholarly journals Compressive Strength Study on the Freeze-thaw Resistance of Recycled Aggregate Concrete Members

2017 ◽  
Vol 11 (1) ◽  
pp. 270-280 ◽  
Author(s):  
Haicheng Niu ◽  
Yonggui Wang ◽  
Xianggang Zhang ◽  
Xiaojing Yin
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Surface Scaling

Introduction: Freeze-thaw resistance of recycled aggregate concrete with partial or total replacement of recycled aggregate compared with that of natural aggregate concrete was investigated in this paper. Method: Ninety specimens were fabricated to study the influence of different recycled aggregate replacement ratios on the surface scaling, mass loss, and residual compressive strength after 100 freeze-thaw cycles. Results: The experiment results indicate that the type of recycled aggregate and its replacement ratio have significant effects on the freeze-thaw performance. The cubic compressive strength of recycled aggregate concrete is overall slightly lower than that of normal concrete. After 100 freeze-thaw cycles, the compressive strength decreases and the reduction extent increases with increasing replacement rate of recycled aggregate. The surface scaling of reinforced recycled concrete prisms tends to be more severe with the increase of freeze-thaw cycles. Conclusion: Furthermore, a notable rise in mass loss and the bearing capacity loss is also found as the substitution ratio increases. Under the same replacement rate, recycled fine aggregate causes more negative effects on the freeze-thaw resistance than recycled coarse aggregate.

scholarly journals Experimental Research on the Wettability of Recycled Aggregate Concrete with Fly Ash

2013 ◽  
Vol 7 (1) ◽  
pp. 232-236
Author(s):  
Yuanchen Guo ◽  
Xue Wang ◽  
Jueshi Qian
Keyword(s):  
Fly Ash ◽  
Moisture Absorption ◽  
Drying Shrinkage ◽  
Absorption Capacity ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Structure Theory ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Main Factors

Material adsorption, the reverse process of evaporation diffusion, directly reflects the wettability of materials. Wettability is one of the main factors that affect the drying shrinkage of materials. A device that measures the wettability of recycled aggregate concrete (RAC) with fly ash is proposed in this study based on pore structure theory. The isothermal absorption curve of RAC is examined with different fly ash contents. Results show that as the recycled aggregate replacement rate increases, the moisture absorption capacity of RAC gradually increases. The addition of fly ash improves the porosity of RAC structures and reduces material wettability.

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