How does the maximum size of aggregate affect the concrete compressive strength?

How does the maximum size of aggregate affect the concrete compressive strength?

A. As the nominal maximum size of the aggregate is increased, the amount of water needed for the same workability is reduced. At the same cementitious material content, strength is therefore greater because the w/cm is lower.

How does aggregate size affect compressive strength?

strengths than the larger sized coarse aggregate. Cook observed that the difference in compressive strengths due to aggregate size is increasingly larger with a decreasing water-to-cement ratio and increasing test age. The smaller sized coarse aggregate also increases the flexural strength of the concrete.

What is the effect of W C ratio on compressive strength of concrete?

If the water-cement proportion is higher, it brings about wider spacing between the cement aggregates and thus, influences the compaction. Correspondingly, concrete’s durability and compressive strength are decreased due to increased dampness levels.

Why maximum size aggregate is important in the mix design of concrete?

Using larger coarse aggregate typically lowers the cost of a concrete mix by reducing cement requirements, the most costly ingredient. Less cement (within reasonable limits for durability) will mean less water if the water-cement (w/c) ratio is kept constant.

What is the maximum aggregate size?

Aggregate Size Nominal Maximum Size: The smallest sieve opening through which the entire amount of aggregate is permitted to pass. coarse aggregate MUST pass the 1.5” sieve but 95 – 100\% MAY pass the 1” sieve, therefore # 57 aggregate is considered to have a Maximum size of 1.5” and an Nominal Maximum size of 1”.

Why it is important to control the maximum size of the coarse aggregate?

The maximum size of coarse aggregate is one of the factors that controls water demand to achieve certain workability. As the maximum size of coarse aggregate reduces, surface area of coarse aggregate increases. Higher the surface area, greater is the water demand to coat the particles and generate workability.

What are the effects of the size shape and texture of aggregates on the strength and workability of concrete?

The shape and texture of aggregate affects the properties of fresh concrete more than hardened concrete. Concrete is more workable when smooth and rounded aggregate is used instead of rough angular or elongated aggregate.

How does size of aggregate affect workability?

Surface area of aggregates depends on the size of aggregates. For a unit volume of aggregates with large size, the surface area is less compared to same volume of aggregates with small sizes. Hence, lower sizes of aggregates with same water content are less workable than the large size aggregates.

How does aggregate size affect water demand?

As the maximum size of coarse aggregate reduces, surface area of coarse aggregate increases. Higher the surface area, greater is the water demand to coat the particles and generate workability.

What is the allowable maximum W C ratio for RCC?

0.70
When w/c is higher than 0.70 all capillary pores are connected. So most of the standards recommend 0.70 as the maximum value for w/c ratio. Higher is the aggressiveness of the environment lower should be the w/c ratio. For concrete exposed to a very aggressive environment, the w/c should be lower than 0.40.

What is the maximum w/c ratio?

The 1997 Uniform Building Code specifies a maximum of 0.5 ratio when concrete is exposed to freezing and thawing in a moist condition or to de-icing chemicals, and a maximum of 0.45 ratio for concrete in a severe or very severe sulfate condition.

What factors affect the performance of concrete mix?

Changes in gradation, maximum size, unit weight, and moisture content can all alter the character and performance of your concrete mix. Economy is another reason for thoughtful aggregate selection. You can often save money by selecting the maximum allowable aggregate size.

What is the effect of W/cm on cement content?

With the w/cm fixed, the larger the nominal maximum size of aggregates, the lower the cement content for a given consistency. Or, stated differently, for a given cement content, the larger the nominal maximum size of aggregate, the lower the water requirement.

What is the ratio of water to concrete?

The concrete mixtures incorporate either basalt or crushed limestone, aggregate sizes of 12 mm (‘h in.) or 19 mm (:Y. in.), and coarse aggregate contents with aggregate volume factors (ACI 211.1-91) of0.75 and 0.67. Water-to-cementitious material ratios range from 0.24 to 0.50.

How does aggregate content affect the compressive strength of high-strength concrete?

High-strength concrete containing basalt and normal-strength concrete containing basalt or limestone yield higher compressive strengths with higher coarse aggregate contents than with lower coarse aggregate contents. The compressive strength of high-strength concrete containing limestone is not affected by aggregate content.