scholarly journals Investigation into the Heat of Hydration and Alkali Silica Reactivity of Sustainable Ultrahigh Strength Concrete with Foundry Sand

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Federico Aguayo ◽  
Anthony Torres ◽  
Tate Talamini ◽  
Kevin Whaley
Keyword(s):  
High Strength ◽  
Heat Of Hydration ◽  
Foundry Sand ◽  
Supplementary Cementitious Material ◽  
Strength Concrete ◽  
Ultrahigh Strength ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar ◽  
The Impact

This study presents the hydration reactivity and alkali silica reaction (ASR) of ultrahigh strength concrete (UHSC) that has been made more sustainable by using spent foundry sand. Spent foundry sand not only is sustainable but has supplementary cementitious material (SCM) characteristics. Two series of UHSC mixtures were prepared using a nonreactive and reactive sand (in terms of ASR) to investigate both the impact of a more reactive aggregate and the use of spent foundry sand. Conduction calorimetry was used to monitor the heat of hydration maintained under isothermal conditions, while ASR was investigated using the accelerated mortar bar test (AMBT). Additionally, the compressive strengths were measured for both series of mixtures at 7, 14, and 28 days to confirm high strength requirements. The compressive strengths ranged from 85 MPa (12,345 psi) to 181.78 MPa (26,365 psi). This result demonstrates that a UHSC mixture was produced. The calorimetry results revealed a slight acceleration in the heat of hydration flow curve compared to the control from both aggregates indicating increased hydration reactivity from the addition of foundry waste. The combination of foundry sand and reactive sand was found to increase ASR reactivity with increasing additions of foundry sand up to 30% replacement.

scholarly journals Accelerated test methods for evaluating alkali-silica reactivity of recycled concrete aggregates

2021 ◽  
Author(s):  
Robert C Johnson
Keyword(s):  
Binding Capacity ◽  
Recycled Concrete ◽  
Test Duration ◽  
Accelerated Tests ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Alkali Silica Reactivity ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar

This thesis reports the findings of a study carried out to determine the effectiveness of Accelerated Tests in evaluating the Alkali-Silica Reactivity of Recycled Concrete Aggregates. The study evaluated the variability of the Accelerated Mortar Bar Test due to test variables as well as the single and multi-laboratory variation. The variability of the Concrete Microbar Test due to test variables and the correlation to results from Accelerated Mortar Bar and Concrete Prism Test results were also evaluated. The tests were corroborated by comparing the porosity, permeability and alkali binding capacity of samples tested by the accelerated tests. It was found that the Accelerated Mortar Bar Test provides acceptable results when the test variables, such as crushing methods and absorption values, are carried out and evaluated properly. The Concrete Microbar Test was found to underestimate the expansion of reactive aggregates. However, the same test was found to provide good correlation to the expansion results of Concrete Prisms incorporating Supplementary Cementing Materials when the test duration was increased.

scholarly journals Reduce the Influence of Horizontal and Vertical Cold Joints on the Behavior of High Strength Concrete Beam Casting in Hot Weather by Using Sugar Molasses

2018 ◽  
Vol 7 (4.19) ◽  
pp. 794
Author(s):  
Fatimah Hameed Naser Al-Mamoori ◽  
Ali Hameed Naser Al-Mamoori
Keyword(s):  
High Strength Concrete ◽  
Concrete Beam ◽  
Setting Time ◽  
Weather Condition ◽  
High Strength ◽  
Point Load ◽  
Concrete Element ◽  
Strength Concrete ◽  
Hot Weather ◽  
The Impact

The current research studies the effect of cold joints on the behavior shear and flexure of High Strength Concrete (HSC) beams caused by delayed casting sequence during the hot weather in summer of Iraq.Fresh concrete should be kept alive during the various casting batches for concrete element by re-vibration. However, the over vibration caused loss in homogeneity and it is difficult to keep the workability of concrete during hot weather due to the effect of setting time.To deal with this problem of improper casting sequence, which eventually leads to the formation of cold joints, it will be used sugar waste (named as Sugar Molasses (SM)) is a by-product resulted from refining process of sugar as a delayed agent to increase the setting time in order to prevent early set of concrete due to adverse effects in construction joint of hot weather.In the current study, the first objective aims to investigate some of fresh and hardened mechanical properties of HSC (with high cement content) using SM at percentages of (0, 0.05, 0.1, 0.2, 0.3) % from the weight of cement under the concept of sustainable development. The second objective aims to investigate the location and surface texture effect of horizontal and vertical cold joints on the flexural and shear behavior of beam with/without SM. This objective includes testing of twenty four plain concrete beam of (110×110×650 mm) under two point load; half of them casting without roughing (smooth) the old layer and the other casted after roughed it.SM content of 0.2% of cement weight can improve compressive strength by about 11.2% at 28 days and delay initial setting time by about 4.617 hours (277 minutes). No adverse effect on concrete have been observed at this dosage of SM concentration for the ages of concrete cylinders studied. Delays in the setting of concrete at this dosage of SM content help in reducing the early setting of concrete and therefore reduced the impact of the cold joints formation in concrete beams under Iraqi hot weather condition. The failure load for the beams with SM of smooth and rough vertical joints is in the range between (1.95 - 2.12) and (1.46-1.37); respectively times that of the case of beam without SM. 

How does fly ash mitigate alkali–silica reaction (ASR) in accelerated mortar bar test (ASTM C1567)?

2013 ◽  
Vol 37 ◽  
pp. 143-153 ◽  
Author(s):  
Seyed M.H. Shafaatian ◽  
Alireza Akhavan ◽  
Hamed Maraghechi ◽  
Farshad Rajabipour
Keyword(s):  
Fly Ash ◽  
Alkali Silica Reaction ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar

scholarly journals Fire Performance of Columns Made of Normal and High Strength Concrete: A Comparative Analysis

2016 ◽  
Vol 711 ◽  
pp. 564-571 ◽  
Author(s):  
Thomas Gernay
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Strength Loss ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Strength Concrete ◽  
The Impact

The use of high strength concrete (HSC) in multi-story buildings has become increasingly popular. Selection of HSC over normal strength concrete (NSC) allows for reducing the dimensions of the columns sections. However, this reduction has consequences on the structural performance in case of fire, as smaller cross sections lead to faster temperature increase in the section core. Besides, HSC experiences higher rates of strength loss with temperature and a higher susceptibility to spalling than NSC. The fire performance of a column can thus be affected by selecting HSC over NSC. This research performs a comparison of the fire performance of HSC and NSC columns, based on numerical simulations by finite element method. The thermal and structural analyses of the columns are conducted with the software SAFIR®. The variation of concrete strength with temperature for the different concrete classes is adopted from Eurocode. Different configurations are compared, including columns with the same load bearing capacity and columns with the same cross section. The relative loss of load bearing capacity during the fire is found to be more pronounced for HSC columns than for NSC columns. The impact on fire resistance rating is discussed. These results suggest that consideration of fire loading limits the opportunities for use of HSC, especially when the objective is to reduce the dimensions of the columns sections.

Applicability of the Accelerated Mortar Bar Test for Alkali-Silica Reactivity of Recycled Concrete Aggregates

2013 ◽  
Vol 2 (1) ◽  
pp. 20120030 ◽  
Author(s):  
Matthew P. Adams ◽  
Angela Jones ◽  
Sean Beauchemin ◽  
Robert Johnson ◽  
Benoit Fournier ◽  
...  
Keyword(s):  
Recycled Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Alkali Silica Reactivity ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar
Sign in / Sign up

Export Citation Format

Share Document