Influence of Water Cement Ratio and Curing on the Permeability and Structure of Hardened Cement Paste and Concrete

1988 ◽  
Vol 137 ◽  
Author(s):  
Herbert Gräf ◽  
Max J. Setzer
Keyword(s):  
Pore Structure ◽  
Structural Changes ◽  
Early Stage ◽  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Systematic Research ◽  
Hardened Cement ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water

AbstractCuring affects sincerely the durability of concrete especially in surface regions. This is reflected in the pore structure and in the permeability. In a systematic research the structural changes due to water cement ratio and curing have been studied by mercury porosimetry, by nitrogen adsorption, by oxygen diffusion and by oxygen permeability. Due to these results diffusion and permeability are connected by a power law. Structural changes alter the permeability by four orders of magnitude. The results can be well explained by pore size distribution both for hcp and for concrete. Carbonation and frost action as well as strength and elastic modulus are closely correlated to permeability and therefore to pore structure. For practical application it is possible to give advice for concreting and curing. Service life can be predicted by permeability measurements in an early stage. The results are comparable with Nyames /20/.

scholarly journals Effect of Phenolic Particles on Mechanical and Thermal Conductivity of Foamed Sulphoaluminate Cement-Based Materials

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3596 ◽  
Author(s):  
Xiuzhi Zhang ◽  
Qing Yang ◽  
Qinfei Li ◽  
Heng Chen ◽  
Guofa Zheng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pore Structure ◽  
Dry Density ◽  
Mechanical And Thermal Properties ◽  
Foaming Agent ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Performance Indexes ◽  
Foamed Concrete ◽  
Inorganic Matrix

Foamed concrete materials based on sulpoaluminate cement were prepared by the chemical foaming method. The effects of water–cement ratio, foaming agent, and foaming stabilizer on the mechanical and thermal properties of foamed concrete were studied. Meanwhile, a portion of cement was replaced with foamed phenolic particles to further optimize the performance of foamed concrete; the results show that when the water–cement ratio was 0.53, the foaming agent content was 5%, the foam stabilizer was 1%, and the substitution of phenolic particles was 20%, the performance indexes of foamed concrete were the best. Methods, describing briefly the main methods or treatments applied: dry density was 278.4 kg/m3, water absorption was 19.9%, compressive strength was 3.01 MPa, and thermal conductivity was 0.072 W/(m·K). By the pore structure analysis of the foamed concrete suing Micro-CT, it was found that when the replacement amount of phenolic particles was 20%, the pore size of foamed concrete was relatively uniform, the minimum D90 was 225 μm respectively. The combination of organic and inorganic matrix and optimized pore structure improved the performance of foamed concrete.

Evaluation Shale Pore Size Spectrum Using Mercury Porosimetry and Nitrogen Adsorption Experiment: A Case Study from the Longtan Formation Shale, Southeastern Hunan, China

2014 ◽  
Vol 962-965 ◽  
pp. 34-40
Author(s):  
Ning Yang ◽  
Shu Heng Tang ◽  
Song Hang Zhang ◽  
Jun Jie Yi
Keyword(s):  
Pore Structure ◽  
Parallel Plate ◽  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Size Spectrum ◽  
Adsorption Experiment ◽  
Structure Characteristics ◽  
Gas Shales ◽  
Strong Ability

Gas shales have a complex pore structure. Using mercury porosimetry and nitrogen adsorption experiment on shale of Longtan Formation in southeastern of Hunan, the pore structure characteristics were contrast analyzed, influencing factors and its impact on reservoir-forming were discussed. Longtan Formation shale is composed of nanopores, include the cylinder pores with two ends open and parallel-plate pores with four sides open. The efficiency of mercury ejection ranges 31.45%~63.82%, 51.94% on average, pores uniformity is well. The size of nanopores is 5~30nm, taking up 94.74% of the total volume and 98.08% of specific surface area. Brittle minerals content is high, as an important parameter influencing pore development. The nanopores have a strong ability to absorb gas, methane molecule exist in a structured way.

Experimental Investigation on the Influence of Water-Cement Ratio on Air-Void Parameters of Cement Concrete

2013 ◽  
Vol 771 ◽  
pp. 29-33
Author(s):  
Jin Xi Zhang ◽  
Chao Wang ◽  
Ming Yang Guo ◽  
Mao Cheng Ma
Keyword(s):  
Experimental Investigation ◽  
Hardened Concrete ◽  
Cement Concrete ◽  
Marked Rise ◽  
Air Voids ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water ◽  
Air Void ◽  
The Impact

This paper studies the effect of water-cement ratio [w/ on the air-void parameters of cement concrete, which has a significant influence on the durability of concrete. Based on the experimental investigation, it is found that the impact on the air content of hardened concrete due to different water-cement ratio is not great. Test results also indicate that with the increase of water-cement ratio, the spacing factors also experienced a marked rise, and the mean diameters as well as the specific areas of air voids evidently increased or declined, respectively, which may lead to an adverse effect on the frost resistance of concrete.

Experimental Study on the Influence of Water Cement Ratio on the Compressive Strength of Shale Ceramsite Concrete

2012 ◽  
Vol 204-208 ◽  
pp. 3895-3898 ◽  
Author(s):  
Zhen Min Cao ◽  
Zhi Gang He ◽  
Yi Yang
Keyword(s):  
Compressive Strength ◽  
Strength Properties ◽  
Light Weight ◽  
Concrete Compressive Strength ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
General Law ◽  
Influence Of Water ◽  
Light Weight Aggregate ◽  
Experimental Preparation

Shale ceramsite concrete is a kind of light weight aggregate concrete. In this paper shale ceramsite concrete compressive strength properties are studied by experimental preparation of different water cement ratio, and made an analysis of compressive strength comparatively among 7 days, 28 days, 56 days. The result shows that the rules of compressive strength of shale ceramsite concrete are in line with the general law strength of concrete, and increases with the age increasing, decreases with water cement ratio increasing, but they are not entirely linear relationship.

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