Effect of Naphthalene Compounded Superplasticizer on Strength and Shrinkage of Ready-Mixed Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 488-495
Author(s):  
Yu Fei Wang ◽  
Han Dong Yan
Keyword(s):  
Cement Paste ◽  
Test Data ◽  
Concrete Strength ◽  
Reducing Agent ◽  
The Other ◽  
General Rules ◽  
Early Strength ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

Superplasticizer is widespread applied in the ready-mixed concrete in China. In the specific engineering, it is not only has the requirement of water-reducing ratio for superplasticizer, but also the superplasticizer has to meet the demand such as early-strength, air-entraining, retarding and so on. In current, the naphthalene compounded superplasticizer is conducted on the basis of the FDN modification. This paper selects two kinds of representative naphthalene compounded superplasticizers, one is the setretarder superplasticizer (WRA1), and the other one is the early strength-air entraining-retarding superplasticizer (WRA2). The effect of performance on neat cement paste, mortar and concrete which mixed with the two admixtures are compared with the benchmarks (not mixed with water reducing agent) and mixed with FDN. Through the analysis and comparison of the test data, the general rules of the naphthalene compounded superplasticizer to concrete strength and shrinkage are put forward in this paper. Also, according to those rules, it poses the concrete problems to be noted in the production. This may have guidance for reducing the early cracks of ready-mixed concrete.

A Study on Incorporating the Tabular CUSUM and Shewhart Control Chart to Monitor Road Surface Quality

2013 ◽  
Vol 723 ◽  
pp. 782-789
Author(s):  
An Pi Chang ◽  
Jyh Dong Lin ◽  
Chien Cheng Chou ◽  
Chen Yu Hsu
Keyword(s):  
Quality Control ◽  
Statistical Analysis ◽  
Control Chart ◽  
Concrete Strength ◽  
Control Analysis ◽  
Rigid Pavement ◽  
Shewhart Control Chart ◽  
Shewhart Control ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

In this article, the Tabular CUSUM (Cumulative Sum) Charts statistic method is employed to analyze the strength quality control of ready-mixed concrete for rigid pavement, for which the CUSUM is also used to analyze and monitor the micro changes of process mean for the strength of the ready-mixed concrete. The result of analytical study supports that the CUSUM statistical analysis skill is more sensitive than the Shewhart Control Chart in terms of designed mixing ratio parameter, water-cement ratio, and admixtures analyzed under the same concrete strength. When micro changes are presented in continuous mean strength value of the ready-mixed concrete, it can detect the continual changes of the concrete quality in a more accurate way. By combining the CUSUM statistical analysis and Shewhart Control Chart, higher accuracy of the quality control analysis could even be achieved in order the enhance quality control performance when pouring the ready-mix concrete on rigid pavement.

The Rheological and Mechanical Performances of Concrete Manufactured with Blended Admixtures Based on Phosphonates

2016 ◽  
Vol 674 ◽  
pp. 159-164 ◽  
Author(s):  
Luigi Coppola ◽  
Sergio Lorenzi ◽  
Stefano Garlati ◽  
Patricia Kara
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Threshold Value ◽  
Strength Gain ◽  
Concrete Mixtures ◽  
Flow Table ◽  
Mechanical Performances ◽  
Ready Mixed Concrete ◽  
Compressive Tests ◽  
Mixed Concrete

The paper deals with the effectiveness of blended phosphonate-based superplasticizers (PHN) for ready mixed concrete. Two phosphonates (PNH1 and PNH2) were added in different percentage to naphthalene sulphonate (NSF) or polycarboxylates (PCEs) based admixtures to improve both compatibility with different cements and workability retention of concrete. The performance of the obtained concrete mixtures was compared to concretes manufactured with the pure NSF or PCE based admixtures. Concretes with the same initial workability (flow table > 580mm) were produced at a temperature of 20 °C and 30 °C. Workability was measured at 0, 30 and 60 minutes to evaluate the flow retention performances of blended superplasticizers. Compressive tests were carried out to study the influence of the superplasticizer on concrete strength gain at the age of 1, 7 and 28 days. PNH1 in combination with NSF improved workability retention with respect to pure NSF, but caused a reduction in the early compressive strength when the dosage exceeded 0.10% (dry polymer vs. cement mass). Dosage of hybrid PCE-PNH superplasticizers to attain the targeted workability was lower with respect to hybrid PNH1/NSF admixtures. PNH1 was more effective than PNH2 in hybrid PCE admixtures in terms of workability retention. A threshold value for PNH dosage (about 0.18 - 0.20 %) exists also in hybrid PCE superplasticizers, but it is about two times higher than that of hybrid PNH1/NSF.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

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