scholarly journals Optimization of Steam-Curing Regime for Recycled Aggregate Concrete Incorporating High Early Strength Cement—A Parametric Study

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2487 ◽  
Author(s):  
Asad Hanif ◽  
Yongjae Kim ◽  
Muhammad Usman ◽  
Cheolwoo Park
Keyword(s):  
Total Duration ◽  
Recycled Aggregate Concrete ◽  
Peak Temperature ◽  
Curing Temperature ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Steam Curing ◽  
Aggregate Concrete ◽  
Early Strength ◽  
Curing Cycle

This paper investigates the properties of steam cured recycled aggregate concrete (RAC), in an attempt to determine the optimum conditions of the steam-curing cycle for RAC, and incorporating high early strength cement (HESC). Varying conditions of steam curing were employed. The steam-curing cycle was set based on the peak temperature, and the duration for which the peak temperature was maintained. Three peak temperatures were used for steam curing, 50 °C, 60 °C, and 70 °C, maintained for up to two hours. The compressive strength results indicated that the steam-curing cycle employing the peak temperature of 50 °C maintained for one hour with a total duration of four hours was the optimum for strength development, both at the early and late stages of hydration. Determining the optimum steam-curing temperature and duration will help reduce the associated curing cost, thus further economizing the production cost of recycled aggregate concrete.

scholarly journals Application of the High Early Strength Type Expansive Agent to the Blast Furnace Slag Combination Concrete with GGBFS under Steam Curing

2019 ◽  
Vol 278 ◽  
pp. 01005
Author(s):  
Erica Enzaki ◽  
Takashi Sakuma ◽  
Eizou Takeshita ◽  
Shigeyuki Date
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Early Stage ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Strength Development ◽  
Steam Curing ◽  
Expansive Agent ◽  
Early Strength ◽  
Furnace Slag

In recent years, the use of blast furnace slag material is being focused as environmental loading reduction and sustainable construction. However, in general, autogeneours shrinkage of the concrete using much amount of GGBFS is large in compared to normal concrete, therefore risk of cracking should be cared. On the other hand, strength development speed of concrete at early stage will be decreasing as the dosage of GGBFS increases, even under steam curing condition. It can be considered these points will be significant disadvantage in both productivity and quality of precast concrete. So in this study, early strength type expansive agent and setting accelerator were used in combination. As a result, it was confirmed that compressive strength at early stage is obviously increased. And steam curing temperature can be reduced about 10 degrees, and also, 600×10-6 of restraint expansion was obtained.

EXPERIMENTAL INVESTIGATION ON SELF CURING RECYCLED AGGREGATE CONCRETE MEMBERS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
V. Bhikshma ◽  
J. Ravi Kumar
Keyword(s):  
Coarse Aggregate ◽  
Heat Of Hydration ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Curing Agent ◽  
Rc Beams ◽  
Aggregate Concrete ◽  
Peg 6000 ◽  
Recycled Coarse Aggregate

Self-curing concrete is an important aspect in strength development, which is neglected due to various reasons such as shortage of water, inaccessibility of structures during curing. Self-curing agents play important role in heat of hydration and strength development. The present study involves the use of self-curing agent polyethylene glycol (PEG 6000). In this investigation, M20 to M50 grade concrete has been considered to evaluate strength characteristics and flexural behavior using natural and recycled aggregate concrete. The various percentages of PEG 6000 have been used. The test result indicates self-curing concrete has indicated strength enhancement compared to conventional curing concrete. The strength for normal coarse aggregate concrete with a self-curing agent (PEG 6000) at 2% with 10% GGBS is decreased when compared with recycled coarse aggregate concrete with 1% (PEG 6000) with addition 10% GGBS. Mechanical properties are 7% to 20% higher for self-curing concrete when compared to natural concrete. Similarly, the flexural strength of normal coarse aggregate concrete was found to be varying from 4% to 16% more than with recycled coarse aggregate concrete at 28 days. Ultimate deflection of RC beams is 10% greater than the NC beams and ultimate moments of RC beams were 1% to 3% less than the corresponding NC beams. The moment-curvature relationship and load-deflection characteristics of the NC beams and RC beams show a similar trend.

scholarly journals Compressive performance of 50 MPa strength concrete-filled square and circular tube (CFT) columns using recycled aggregate

2018 ◽  
Author(s):  
Sung-Mo Choi ◽  
Won Ho Choi ◽  
Kangseok Lee ◽  
Jae-Yong Ryoo ◽  
Sunhee Kim ◽  
...  
Keyword(s):  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Steel Pipe ◽  
Strength Development ◽  
Fine Aggregate ◽  
Mixing Ratio ◽  
Compressive Behavior ◽  
Aggregate Concrete ◽  
Cft Column

Recycled aggregate is an environmentally self-sustainable solution that can reduce construction waste and replace natural aggregates. However, there is a disadvantage in concrete such as initial strength drop and long-term strength development. Therefore, the interaction effect of the two materials can be expected by filling the cyclic aggregate concrete in the CFT column. In order to develop a concrete with compressive strength of 50 MPa as a recycled aggregate, we carried out a mixing experiment and fabricated 18 specimens to confirm the compressive behavior of a RCFT (Recycled Concrete Filled Tube) column that can be applied to actual buildings. Variable is the shape and thickness of steel pipe, concrete strength and mixing ratio, and coarse aggregate and fine aggregate are all used as recycled aggregate. The optimum mixing ratio for recycled aggregate concrete to be filled in the CFT filled steel pipe was found through three concrete preliminary mixing experiments. In addition, the compression test of the RCFT column was carried out to observe and analyze the buckling shape of the CFT column. Based on the analysis of the buckling configuration and the experimental data, the load-displacement curves of the specimens were drawn and the compressive behavior was analyzed. 

scholarly journals The estimation of compressive strength of normal and recycled aggregate concrete

2011 ◽  
Vol 9 (3) ◽  
pp. 419-431 ◽  
Author(s):  
Ksenija Jankovic ◽  
Dragan Nikolic ◽  
Dragan Bojovic ◽  
Ljiljana Loncar ◽  
Zoran Romakov
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Concrete Strength ◽  
Recycled Aggregate Concrete ◽  
Curing Temperature ◽  
Recycled Aggregate ◽  
Coefficient Of Determination ◽  
Aggregate Concrete ◽  
Ready Mixed Concrete

Estimation of concrete strength is an important issue in ready-mixed concrete industry, especially, in proportioning new mixtures and for the quality assurance of the concrete produced. In this article, on the basis of the existing experimental data of compressive strength of normal and recycled aggregate concrete and equation for compressive strength calculating given in Technical regulation are compared. The accuracies of prediction by experimental data obtained in laboratory as well as by EN 1992-1-1, ACI 209 and SRPS U.M1.048 are compared on the basis of the coefficient of determination. The determination of the compressive strengths by the equation described here relies on determination of type of cement and age of concrete with the constant curing temperature.

scholarly journals Geopolymer Recycled Aggregate Concrete: From Experiments to Empirical Models

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1180
Author(s):  
Hoai-Bao Le ◽  
Quoc-Bao Bui ◽  
Luping Tang
Keyword(s):  
Sodium Hydroxide Solution ◽  
Empirical Models ◽  
Recycled Aggregate Concrete ◽  
Curing Temperature ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Fine Aggregate ◽  
River Sand ◽  
Conventional Concrete ◽  
Aggregate Concrete

Ordinary cement concrete is a popular material with numerous advantages when compared to other construction materials; however, ordinary concrete is also criticized from the public point of view due to the CO2 emission (during the cement manufacture) and the consumption of natural resources (for the aggregates). In the context of sustainable development and circular economy, the recycling of materials and the use of alternative binders which have less environmental impacts than cement are challenges for the construction sector. This paper presents a study on non-conventional concrete using recycled aggregates and alkali-activated binder. The specimens were prepared from low calcium fly ash (FA, an industrial by-product), sodium silicate solution, sodium hydroxide solution, fine aggregate from river sand, and recycled coarse aggregate. First, influences of different factors were investigated: the ratio between alkaline activated solution (AAS) and FA, and the curing temperature and the lignosulfonate superplasticizer. The interfacial transition zone of geopolymer recycled aggregate concrete (GRAC) was evaluated by microscopic analyses. Then, two empirical models, which are the modified versions of Feret’s and De Larrard’s models, respectively, for cement concretes, were investigated for the prediction of GRAC compressive strength; the parameters of these models were identified. The results showed the positive behaviour of GRAC investigated and the relevancy of the models proposed.

Experiment Research on Basic Mechanic Property of Recycled Concrete with Different Ratio of Recycled Aggregate

2011 ◽  
Vol 250-253 ◽  
pp. 994-1000
Author(s):  
Yue Dong Sun ◽  
Xiang Xiao
Keyword(s):  
Compressive Strength ◽  
Elasticity Modulus ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Experiment Research ◽  
Crushing Strength ◽  
Aggregate Concrete ◽  
Mechanic Property

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.

Study on Preparation of High Early Strength Recycled Aggregate Concrete

2013 ◽  
Vol 639-640 ◽  
pp. 404-410
Author(s):  
Jian Yin ◽  
Wei Min Song ◽  
Yi Chi ◽  
Wei Zou
Keyword(s):  
Influencing Factor ◽  
Empirical Relationship ◽  
Recycled Aggregate Concrete ◽  
Mineral Admixture ◽  
Recycled Aggregate ◽  
Orthogonal Experimental Design ◽  
Aggregate Concrete ◽  
Binder Ratio ◽  
Early Strength ◽  
Water Binder Ratio

An orthogonal experimental design method was adopted for the mix design of high early strength recycled aggregate concrete (HSRAC), and the influence of water-binder ratio, percentage of recycled aggregate(RA）and highly active compound mineral admixture (HACMA) content on the strength of the concrete was discussed. The test results indicated that water-binder ratio was the most principal and significant influencing factor on the strength of HSRAC, regardless of age. An empirical relationship among the strength of HSRAC, the water-binder ratio, the percentage of recycled aggregate and HACMA content was proposed by using multivariate regression analysis. The demand of opening heavy or heavier traffics and rapid repair concrete on strength to HSRAC could be all met.

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