What causes the weakening of the strength of concrete?

What causes the weakening of the strength of concrete?

When excess water creates greater spaces between aggregate materials, the voids fill with air after the moisture evaporates. The resulting inadequate compaction reduces the concrete’s strength. Concrete with trapped air levels as little as 10 percent experiences reductions in strength of up to 40 percent.

What are the factors that affect the strength and workability of concrete?

The Factors that Affect the Workability of Concrete are Given Below:

• Water Content of the Concrete Mix:
• The Size of Aggregates:
• The shape of Aggregates:
• Surface Texture of Aggregates:
• The Porosity of Aggregates:
• Grading of Aggregates:
• Uses of Concrete Admixtures:
• Ambient Temperature:

What has the biggest impact on the strength of concrete?

Water to Cement Ratio: The ratio of the weight of water to the weight of cement is called the Water/Cement ratio. It is the most important factor for gaining the strength of concrete.

What affects the tensile strength of concrete?

This chapter reviews various influences that affect the tensile strength of concrete. These influences include composition (e.g. type of aggregate and water cement ratio), age and curing, as well as environmental effects such as sustained loading.

What causes concrete to deteriorate?

Concrete degradation may have various causes. Concrete can be damaged by fire, aggregate expansion, sea water effects, bacterial corrosion, calcium leaching, physical damage and chemical damage (from carbonatation, chlorides, sulfates and non-distilled water).

What causes concrete failure?

The two most common causes of failure are carbonation and chloride contamination of the concrete. Both of these lead to corrosion of the embedded steel reinforcement and as the steel corrodes it expands and exerts pressure on the concrete so that, eventually, the concrete cracks and spalls.

What are the two most important factors affecting strength of concrete?

Two of the most important factors that affect concrete strength are: a the cement-aggregate ratio and curing time.

Which factor affects workability of concrete?

Factors affecting the workability of concrete are materials such as water content, cement concrete, sand and aggregate properties such as size, shape, grading, mix design ratio and use of admixtures.

What are the causes of deterioration of concrete?

Main Causes of Concrete Deterioration Are:

• Corrosion of Rebars or Other Embedded Metals. Exposure of R.C concrete to chloride ions.
• Freezing and Thawing. Expansion of Aggregates.
• Chemical Attack. Exposure to Acid Attack.
• Alkali-Aggregate Action.
• Abrasion or Erosion of Concrete Surfaces.
• Fire and Heat Action.
• Volume Changes.

What are the factors affecting strength of a compression member?

These factors include member slenderness, material nonlinearity, initial imperfections in geometry (out-‐of-‐straightness), and partial yielding accentuated by residual stresses.

How porosity affect the strength of concrete?

The primary factor that governs the strength of brittle materials, like concrete, is porosity. As the capillary porosity decreases compressive strength increases. Also there is data to indicate that large pores may be more effective than small pores in reliving stress concentrations at crack tips.

How do you weaken concrete?

Spread your phosphoric acid or trisodium phosphate over the concrete area you want to clean first, using a mixture with water that’s recommended by the individual manufacturer. Use a brush to scrub the acid into the concrete. These are weaker acids that just might work to dissolve a sufficient amount of concrete.

How does cement content affect strength of concrete?

Aggregate / Cement Ratio. The influence of cement content on workability and strength is an important one to remember and can be summarized as follows: For a given workability an increase in the proportion of cement in a mix has little effect on the water demand and results in a reduction in the water/cement ratio.

How does workability affect the strength of concrete?

However if the workability becomes too low the concrete becomes difficult to compact and the strength reduces. For a given set of materials and environment conditions, the strength at any age depends only on the water-cement ratio, providing full compaction can be achieved.

How is the strength of a concrete cylinder affected?

The concrete strength is affected by the shape and size of the specimens, but high strength concretes is less affected than the low strength. Concrete Fig.14.3 shows the influence of height/diameter ratio on the strength of cylinder for different strength of concrete as suggested by Murdok and Kesler. Failure of Compression Specimens:

How is the compressive strength of concrete determined?

Depending on the water-cement ratio, the compressive strength is defined in the mix designs. When we required a certain grade of concrete, firstly we select an appropriate water-cement ratio to proceed with the mix design. As indicated in the above figure, the increase of the water/cement ration reduces the compressive strength of the concrete.