Self-consolidating concrete properties with binary and ternary blends in hot weather

Author(s):  
Samer Al-Martini ◽  
Mohammed I. Al-Khatib
2022 ◽  
Author(s):  
Walid E. Elemam ◽  
Ahmed H. Abdelraheem ◽  
Mohamed G. Mahdy ◽  
Ahmed M. Tahwia

2021 ◽  
Vol 904 ◽  
pp. 453-457
Author(s):  
Samer Al Martini ◽  
Reem Sabouni ◽  
Abdel Rahman Magdy El-Sheikh

The self-consolidating concrete (SCC) become the material of choice by concrete industry due to its superior properties. However, these properties need to be verified under hot weather conditions. The paper investigates the behavior of SCC under hot weather. Six SCC mixtures were prepared under high temperatures. The SCC mixtures incorporated polycarboxylate admixture at different dosages and prolonged mixed for up to 2 hours at 30 °C and 40 °C. The cement paste was replaced with 20% of fly ash (FA). The fresh properties were investigated using slump flow, T50, and VSI tests. The compressive strength was measured at 3, 7, and 28 days. The durability of SCC mixtures was evaluated by conducting rapid chloride penetration and water absorption tests.


2016 ◽  
Vol 677 ◽  
pp. 254-259 ◽  
Author(s):  
Mohamed Al Khatib ◽  
Samer Al Martini

Self-consolidating concrete (SCC) has recently drawn attention to the construction industry in hot weather countries, due to its high fresh and mechanical properties. The slump flow is routinely used for quality control of SCC. Experiments were conducted by the current authors to investigate the effects of hot weather conditions on the slump flow of SCC. Self-consolidating concrete mixtures were prepared with different dosages of fly ash and superplasticizer and under different ambient temperatures. The results showed that the slump flow of SCC is sensitive to changes in ambient temperature, fly ash dosage, and superplasticizer dosage. In this paper, several artificial neural networks (ANNs) were employed to predict the slump flow of self-consolidating concrete under hot weather. Some of the data used to construct the ANNs models in this paper were collected from the experimental study conducted by the current authors, and other data were gathered from literature. Various parameters including ambient temperature and mixing time were used as inputs during the construction of ANN models. The developed ANN models employed two neural networks: the Feed-Forward Back Propagation (FFBP) and the Cascade Forward Back Propagation (CFBP). Both FFBP and CFBP showed good predictability to the slump flow of SCC mixtures. However, the FFBP network showed a slight better performance than CFBP, where it better predicted the slump flow of SCC than the CFBP network under hot weather. The results in this paper indicate that the ANNs can be employed to help the concrete industry in hot weather to predict the quality of fresh self-consolidating concrete mixes without the need to go through long trial and error testing program.Keywords: Self-consolidating concrete; Neural networks; Hot weather, Feed-forward back-propagation, Cascade-forward back propagation.


2016 ◽  
Vol 677 ◽  
pp. 3-7 ◽  
Author(s):  
Samer Al Martini ◽  
Mohamed Al Khatib

Self-consolidating-concrete (SCC) has gained wide acceptance in the construction industry given its ability to reduce construction duration and cost. All ready-mix concrete commonly used in hot weather countries, such as United Arab Emirates (UAE), is subjected to continuous agitation during hauling to construction sites. Prolonged mixing, especially at high temperatures can lead to loss of workability and increased difficulties for concrete placement and consolidation. This may result in lower mechanical and durability properties. In this paper, the mechanical and durability properties of self-consolidating concrete (SCC) under hot weather conditions were investigated. Mixing and testing were conducted outdoor at the construction material lab of Abu Dhabi University during last summer of 2014. The test results showed that the mixing time and hot weather adversely affected the fresh properties. The SCC mixtures were continuously mixed for 2 hours under a temperature ranged from 25 to 40 °C, to simulate concrete in a transit truck during transportation to a construction site under hot weather. Polycarboxylate-based high-range water-reducing admixture (PC) and fly ash were incorporated in the investigated SCC mixtures. The results showed that both the compressive strength and durability of SCC were highly affected by fly ash dosage and temperature.Keywords: Hot weather; hauling time, self-consolidating concrete.


2019 ◽  
pp. 6-10
Author(s):  
Yousif Hummaida Ahmed

Self-compacting concrete (SCC) is a special type of concrete able to flow and compact under its self-weight. The SCC requires high powder content (mainly of cement) up to 600kg/m3 to achieve its properties. This will be problematic if all cement content in the powder exceeded 400 kg/m3used in hot weather of Sudan. This paper investigates addition of Sudanese limestone powder (LSP) to reduce cement content. The LSP dosages between 20% and 28 % (by cement weight) are used in six mixes having maximum cement content 380kg/m3. Results show that five trial mixes achieved the self-compactibility tested by slump flow, sieve segregation, V-funnel and U-box tests. Compressive strength of these mixes show that the LSP increases strength with dosage. Therefore, further investigations of hardened concrete properties are recommended for the successful mixes to be applied in real projects in the Sudan. Also, it has been found that dry batching and forced-action pan mixers are the most suitable for producing SCC with high homogeneity compared to commercial tilted-drum mixers.


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