scholarly journals Determination of the Optimum Amount of Superplasticizer Additive for Self-Compacting Concrete

2020 ◽  
Vol 10 (9) ◽  
pp. 3096 ◽  
Author(s):  
Jose A. Sainz-Aja ◽  
Isidro A. Carrascal ◽  
Juan A. Polanco ◽  
Israel Sosa ◽  
Carlos Thomas ◽  
...  
Keyword(s):  
Power Consumption ◽  
Saturation Point ◽  
Self Compacting Concrete ◽  
Optimum Amount ◽  
Concrete Mixer

Self-compacting concrete modifies its workability with small variations in the amount of superplasticizer additive. For this reason, large number of tests are required to monitor its workability. In order to determine the appropriate amount of additive for a single mix, the evolution of the power consumption of the concrete mixer during the addition of small amounts of additive to the concrete was analyzed. These results were compared both with typical workability characterization for self-compacting concrete and with the saturation point results, determined by the Marsh cone method. After this comparison, a good correlation was obtained between the results from the traditional tests and the proposed “concrete mixer method”.

scholarly journals Saturation Point of Superplasticizers Determined by Rheological Tests for Self Compacting Concrete

2017 ◽  
Author(s):  
Mehena Oualit ◽  
Amar Irekti ◽  
Yannick Melinge
Keyword(s):  
Experimental Research ◽  
Coaxial Cylinder ◽  
Mix Design ◽  
Saturation Point ◽  
Self Compacting Concrete ◽  
Mix Proportioning ◽  
Concrete Mix ◽  
Final Adjustment ◽  
Definition Of

The dosage of superplasticizer is first determined in mortar mixtures and it is after adjusted in concrete mix trials. Other self compacting concrete (SCC) mix proportioning methods rely on the definition of the superplasticizer saturation dosage in pastes. These approaches to mix design have advantages over the ones based exclusively on concrete batching because it is less expensive and material demanding to perform tests in mortar and paste than in concrete. This paper presents the results of an experimental research carried out to investigate the use of tests performed in paste to define the optimum dosage of superplasticizer for self-compacting concrete. The materials employed were Portland cement, pozzolana and three types of superplasticizers: poly naphthalene sulfonate (PNS), poly melamine sulfonate (PMS) and a polycarboxylate. The saturation point of each superplasticizer was determined in pastes by rheological tests using a coaxial cylinder rheometer AR2000. Self-compacting concretes were prepared using the superplasticizer contents found. The results obtained led to the conclusion that in SCC mixture proportioning methods, the determination of the superplasticizer content in the paste phase is paramount. Nevertheless, final adjustment of w/c+f ratio was always needed in order to produce SCC.

Variation in the respiratory quotient of birds and implications for indirect calorimetry using measurements of carbon dioxide production

1995 ◽  
Vol 198 (1) ◽  
pp. 213-219 ◽  
Author(s):  
G Walsberg ◽  
B Wolf
Keyword(s):  
Carbon Dioxide ◽  
Power Consumption ◽  
Indirect Calorimetry ◽  
Respiratory Quotient ◽  
Current Knowledge ◽  
Bird Species ◽  
Passer Domesticus ◽  
Carbon Dioxide Production ◽  
Accurate Estimation

Determination of animal power consumption by indirect calorimetry relies upon accurate estimation of the thermal equivalent of oxygen consumed or carbon dioxide produced. This estimate is typically based upon measurement or assumption of the respiratory quotient (RQ), the ratio of CO2 produced to O2 consumed. This ratio is used to indicate the mixture of lipids, carbohydrates and proteins in the metabolic substrate. In this analysis, we report the RQ for two bird species, Passer domesticus and Auriparus flaviceps, under several dietary and fasting regimes. RQ commonly differed substantially from those typically assumed in studies of energy metabolism and often included values below those explainable by current knowledge. Errors that could result from these unexpected RQ values can be large and could present the primary limit to the accuracy of power consumption estimates based upon measurement of carbon dioxide production.

Fracture Toughness and Cracking Behaviour of SCC Compared to VC

2013 ◽  
Vol 577-578 ◽  
pp. 205-208
Author(s):  
Sara Korte ◽  
Veerle Boel ◽  
Wouter de Corte ◽  
Geert de Schutter
Keyword(s):  
Fracture Toughness ◽  
Fracture Process ◽  
Critical Value ◽  
Fracture Parameter ◽  
Self Compacting Concrete ◽  
Bending Tests ◽  
Three Point Bending ◽  
Notched Specimens ◽  
Subsequent Determination

Vibrated concrete (VC) and self-compacting concrete (SCC) have a substantially different composition, resulting in dissimilar mechanical properties regarding cracking behaviour. The critical value of the mode I stress-intensity factor KICis an appropriate fracture parameter for evaluating fracture toughness and can be obtained from three-point bending tests (3PBT) on small, notched specimens. Subsequent determination of the energy release rate thus allows to examine the crack propagation and fracture process of both concrete types. This paper describes the results of such 3PBTs on samples, made from VC and SCC. Evaluation of the cracking behaviour, derived from these results, reveals remarkable differences.

scholarly journals Determination of fiber saturation point of rattan (Calamus simplicifolius) using the LF-NMR and two conventional methods

2020 ◽  
Vol 54 (3) ◽  
pp. 667-682
Author(s):  
Limei Yang ◽  
Genlin Tian ◽  
Shumin Yang ◽  
Lili Shang ◽  
Xing’e Liu ◽  
...  
Keyword(s):  
Fiber Saturation Point ◽  
Saturation Point ◽  
Fiber Saturation ◽  
Conventional Methods ◽  
Calamus Simplicifolius ◽  
Lf Nmr
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