scholarly journals Influence of Coarse Aggregate Type on the Mechanical Strengths and Durability of Cement Concrete

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1036
Author(s):  
Lin Wang ◽  
Han Yong ◽  
Jinyu Lu ◽  
Chunxue Shu ◽  
Hui Wang
Keyword(s):  
Coarse Aggregate ◽  
Penetration Resistance ◽  
Shrinkage Rate ◽  
Cement Concrete ◽  
Freeze Thaw ◽  
Slump Flow ◽  
Binder Ratio ◽  
Chloride Penetration Resistance ◽  
Mechanical Strengths ◽  
Curing Age

In this paper, the influence of coarse aggregate on the slump flow and the following mechanical strengths (flexural and compressive strengths), the shrinkage rate, the chloride penetration resistance, and the freeze–thaw resistance were investigated. Water–binder ratios in this study were 0.22, 0.30, 0.34, and 0.45. Sand ratio in this study was 0.45. All samples were cured for 7 d, 14 d, 28 d, and 56 d, respectively. Results indicated that the fluidity of cement concrete with different coarse aggregate increased in this order: gneiss < limestone < basalt < diabase. The mechanical strengths and shrinkage rate increased obviously with the increasing curing age when the curing age ranged from 7 days to 28 days. However, the mechanical strengths and shrinkage rate trended to a stable value when the increasing curing age increased from 28 days to 56 days. The mechanical strengths with different coarse aggregate increased in this order: diabase < basalt < limestone < gneiss. Meanwhile, the shrinkage rate demonstrated this trend of development: diabase < basalt < limestone < gneiss. The resistance to freeze–thaw cycles of cement concrete decreased with the increasing water–binder ratio. Meanwhile, the resistance to freeze–thaw cycles was closely related to the types of coarse aggregate.

scholarly journals The Rapid Chloride Migration Test in Assessing the Chloride Penetration Resistance of Normal and Lightweight Concrete

2021 ◽  
Vol 11 (16) ◽  
pp. 7251
Author(s):  
Jorge Pontes ◽  
José Alexandre Bogas ◽  
Sofia Real ◽  
André Silva
Keyword(s):  
Lightweight Concrete ◽  
Chloride Transport ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Migration Test ◽  
Simple Method ◽  
Chloride Migration ◽  
Binder Ratio ◽  
Chloride Penetration Resistance ◽  
Water Binder Ratio

Chloride-induced corrosion has been one of the main causes of reinforced concrete deterioration. One of the most used methods in assessing the chloride penetration resistance of concrete is the rapid chloride migration test (RCMT). This is an expeditious and simple method but may not be representative of the chloride transport behaviour of concrete in real environment. Other methods, like immersion (IT) and wetting–drying tests (WDT), allow for a more accurate approach to reality, but are laborious and very time-consuming. This paper aims to analyse the capacity of RCMT in assessing the chloride penetration resistance of common concrete produced with different types of aggregate (normal and lightweight) and paste composition (variable type of binder and water/binder ratio). To this end, the RCMT results were compared with those obtained from the same concretes under long-term IT and WDT. A reasonable correlation between the RCMT and diffusion tests was found, when slow-reactive supplementary materials or porous lightweight aggregates surrounded by weak pastes were not considered. A poorer correlation was found when concrete was exposed under wetting–drying conditions. Nevertheless, the RCMT was able to sort concretes in different classes of chloride penetration resistance under distinct exposure conditions, regardless of the type of aggregate and water/binder ratio.

Proportion Design of Autoclaved Cement Concrete Based on High Strength

2011 ◽  
Vol 391-392 ◽  
pp. 161-164
Author(s):  
Tie Quan Ni ◽  
Chang Jun Ke ◽  
Li Zhang
Keyword(s):  
Coarse Aggregate ◽  
High Strength ◽  
Orthogonal Test ◽  
Mineral Admixture ◽  
Mix Design ◽  
Hydration Reaction ◽  
Cement Concrete ◽  
Binder Ratio ◽  
Four Levels ◽  
Water Binder Ratio

According to the particularity of the autoclaved cement concrete that partial aggregate could participate in hydration reaction in the process of autoclaving, the optimal gradation of coarse aggregate and the optimal slurry aggregate ratio is studied, and the effect of water reducing agent for fluidity of cement paste is also studied. The optimized mix design of autoclaved cement concrete based on high strength (compressive strength and flexural strength) is done by orthogonal test with four factors (water-binder ratio, type of mineral admixture, amount and sand ratio) and four levels.

Influence of Curing Age and Water-Binder Ratio on Chloride Permeability under Freeze-Thaw and Load

2013 ◽  
Vol 405-408 ◽  
pp. 2610-2615
Author(s):  
Lei Hong ◽  
Run Min Duo
Keyword(s):  
Diffusion Coefficients ◽  
High Performance ◽  
High Performance Concrete ◽  
Chloride Diffusion ◽  
Chloride Permeability ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Binder Ratio ◽  
Water Binder Ratio ◽  
Curing Age

The chloride diffusion coefficients of different water-binder ratio high performance concrete (HPC) subjected to different one-way loads，freeze-thaw cycles and different standard curing ages were measured by electro-migration (RCM) tests and the results were analyzed. The test results indicate that with the increase of one-way load, its influence on the chloride permeability of different water-binder ratio HPC rises in the same proportion. The influence of the curing age on the chloride permeability of HPC will decrease with the reduction of the water-binder ratio of HPC. Under the same freeze-thaw cycle conditions, the relationships between chloride diffusion coefficients of different water-binder ratio HPC and curing ages are nearly suitable to power function.

scholarly journals Influence of NaCl Freeze Thaw Cycles and Cyclic Loading on the Mechanical Performance and Permeability of Sulphoaluminate Cement Reactive Powder Concrete

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1227
Author(s):  
Xinghua Hong ◽  
Hui Wang ◽  
Feiting Shi
Keyword(s):  
Cyclic Loading ◽  
Mechanical Performance ◽  
Strength Loss ◽  
Steel Fibers ◽  
Freeze Thaw ◽  
Sulphoaluminate Cement ◽  
Compressive And Flexural Strengths ◽  
Reactive Powder ◽  
Mechanical Strengths ◽  
Curing Age

This paper aimed to investigate the coupling effects of NaCl freeze–thaw cycles and cyclic loading on the mechanical performance and permeability of sulphoaluminate cement reactive powder concrete (RPC). Firstly, the compressive and flexural strengths of sulphoaluminate cement RPC were investigated. Then, the chloride ion permeability, mechanical strengths (compressive and flexural strengths) and mass loss were determined. Results indicated that the increased steel fibers content and curing age played positive roles in the mechanical strengths. The threshold values of steel fibers and curing age were 3.0% and 14 days. Sulphoaluminate cement RPC with early curing age (5 h) showed relatively high mechanical strengths: flexural strength (8.69~17.51 MPa), and compressive strength (34.1~38.5 MPa). The mass loss, the chloride migration coefficient, and the compressive strength loss increased linearly with NaCl freeze–thaw cycles. Meanwhile, the flexural strength loss increased with the exponential function. The relative dynamic modulus of elasticity of specimens decreased linearly with the increased freeze–thaw cycles. Finally, it was observed from this paper, cyclic loading demonstrated negative roles on the mechanical strengths and resistance to chloride penetration.

A Study on the Influence of Coarse Aggregate on Rheological Properties of Self-Compacting Concrete

2014 ◽  
Vol 633 ◽  
pp. 130-135
Author(s):  
Yu Chuan Jiang ◽  
Da Huo ◽  
Hai Wen Teng ◽  
Jin E Xu
Keyword(s):  
Particle Size ◽  
Rheological Properties ◽  
Coarse Aggregate ◽  
Volume Ratio ◽  
Flow Time ◽  
Self Compacting Concrete ◽  
Slump Flow ◽  
Binder Ratio ◽  
Funnel Flow ◽  
Water Binder Ratio

This paper presences the influence of coarse aggregate-space coefficient on the rheological properties of self-compacting concrete (SCC). The results indicate that coarse aggregate-space coefficient has significant influence on slump flow and V-funnel flow time of SCC, when the maximum aggregate particle size is 16mm and the volume ratio of sand and motor is 0.43, meanwhile water binder ratio is 0.38. The higher the coarse aggregate-space coefficient, the lager the slump flow, the shorter the V-funnel flow time. The range of coarse aggregate-space coefficient of SCC is suitable for 1.31~1.58 under the condition of the paper. The suitable range can guarantee excellent rheological properties and stability of SCC mixture. There is little effect of coarse aggregate-space coefficient on compressive strength in this paper tests.

scholarly journals Influence of NaCl Freeze–Thaw Cycles on the Mechanical Strength of Reactive Powder Concrete with the Assembly Unit of Sulphoaluminate Cement and Ordinary Portland Cement

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1238
Author(s):  
Zhangjie Cai ◽  
Hui Wang
Keyword(s):  
Loss Rate ◽  
Quadratic Function ◽  
Strength Loss ◽  
Polypropylene Fibers ◽  
Freeze Thaw ◽  
Sulphoaluminate Cement ◽  
Binder Ratio ◽  
Compressive And Flexural Strengths ◽  
Reactive Powder ◽  
Mechanical Strengths

The influence of sulphoaluminate cement and the dosage of polypropylene fibers on the basic mechanical strengths (compressive and flexural strengths) of reactive powder concrete (RPC) cured for 1 d, 3 d, 7 d, 14 d and 28 d is studied in this research. The content of sulphoaluminate cement ranges from 0% to 100% and the dosages of polypropylene fibers are 0%~3.5%, respectively. Moreover, the mechanical properties (compressive and flexural strengths), the relative dynamic elastic modulus (RDEM) and the chloride permeability of specimens with 50% sulphoaluminate cement and different dosages of polypropylene fibers are determined after the specimens are exposed to different NaCl freeze–thaw cycles. The water–binder ratio in this study is 0.25, and the sand-to-binder ratio is 1.25. Results show that the relationship between the mechanical strengths of RPC at early curing ages (lower than 7 d) and the sulphoaluminate cement content is a linear function with a positive correlation. However, when the curing age reaches 14 d, the compressive and flexural strengths decrease in the form of a linear function with the addition of sulphoaluminate cement. The correlation between the mechanical strengths and polypropylene fiber volume is a positive quadratic function. However, the mass loss rate and flexural strength loss rate increased in the form of a quadratic function, and RDEM shows a negative quadratic function with the freeze–thaw cycles. Moreover, the compressive strength loss rate increases linearly with the freeze–thaw cycle. The addition of polypropylene fibers can effectively improve the freeze–thaw resistance of cement mortar with an assembly unit of ordinary cement and sulphoaluminate cement.

scholarly journals CHLORIDE PENETRATION RESISTANCE OF CONCRETE SEALER AND COATING SYSTEMS

2015 ◽  
Vol 21 (4) ◽  
pp. 492-502 ◽  
Author(s):  
Khaled A. Soudki ◽  
Md. Safiuddin ◽  
Paul Jeffs ◽  
Gary Macdonald ◽  
Marcos Kroker
Keyword(s):  
Concrete Surface ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Water Soluble ◽  
Test Results ◽  
Nacl Solution ◽  
Total Water ◽  
Freeze Thaw ◽  
Powder Samples ◽  
Chloride Penetration Resistance

This study investigated the chloride penetration resistance of a silane-based sealer (SS1), an acrylic-based coating (AC1), and two cementitious coatings (CC1 and CC2) when applied on concrete surface. Concrete powder samples were collected from 15, 30 and 45 mm depths of sealer and coating treated concrete prism specimens, which were exposed to H2O and de-icing solutions of NaCl, Geomelt S30, MgCl2 and CaCl2 for 100 freeze-thaw cycles followed by 25 wet-dry cycles. Chloride analysis was carried out to determine the total water-soluble chlorides of concrete. Test results revealed that the chloride penetration for exposure to the de-icing chemicals occurred at a depth of 15 mm from the concrete surface. The highest chloride penetration occurred for the non-treated concrete. The sealer ‘SS1’ exhibited good performance except with exposure to NaCl solution. Among the three different coating products, the acrylic-based coating ‘AC1’ was the best-performing coating, whereas the cementitious coating ‘CC1’ had the worst performance. The amount of penetrated water-soluble chlorides was greater than the maximum recommended value of 0.025% (by concrete weight) at 15 mm depth for the sealer ‘SS1’ when exposed to NaCl de-icing solution, and for the coating ‘CC1’ when exposed to NaCl, CaCl2 and MgCl2 solutions.

scholarly journals Influence of Lightly Burned MgO on the Mechanical Properties and Anticarbonization of Cement-Based Materials

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 714
Author(s):  
Lin Wang ◽  
Chao Li ◽  
Chunxue Shu ◽  
Han Yong ◽  
Jianmin Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Shear Stress ◽  
Cement Paste ◽  
Plastic Viscosity ◽  
Expansion Rate ◽  
Cement Concrete ◽  
Slump Flow ◽  
Cement Based Materials ◽  
Curing Age

This study aims to study the influence of a lightly burned magnesium oxide (LBMO) expansion agent on the rheological properties (the slump flow, plastic viscosity and variation of shear stress) of cement-based materials. Four different mass contents (i.e., 0%, 3%, 6% and 9%) of LBMO were selected. The following compressive strength and expansion value of the corresponding cement concrete were tested. Cement concrete with two strength grades of 30 MPa and 50 MPa (C30 and C50) was selected. Results indicated that the addition of LBMO can effectively decrease the fluidity and increase the plastic viscosity of fresh cement paste. An optimum dosage (3%) of LBMO is the most advantageous to the compressive strength of cement concrete. The addition of LBMO can increase the expansion rate of cement concrete, thus preventing inside cracks. Moreover, the incorporation of LBMO led to a reduction in the fluidity of the cement paste and an increase in plastic viscosity. The addition of LBMO can increase the expansion rate of cement concrete, thus preventing inside cracks. It can be found that little difference exists in the compressive strength and the expansion rate of cement concrete with strength grades of 30 MPa and 50 MPa. Finally, the increased dosage of LBMO, curing age and compressive strength led to improving the carbonization resistance of cement concrete.

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