SSD stands for saturated surface-dry and it describes a condition that a concrete surface must be brought to when a cement product is to be applied to it. The surface is SSD when the substrate is saturated with water, filling the voids in the substrate's aggregate, but the outer surface is devoid of free water.
Bulk SSD Specific Gravity: The ratio of the weight in air of a unit volume of aggregate, including the weight of water within the voids filled to the extent achieved by submerging in water for approximately 15 hours, to the weight in air of an equal volume of gas-free distilled water at the stated temperature.
Subtract the dry weight from the wet weight and divide the difference by the dry weight. Multiply the. answer by 100 to obtain the percent of total moisture in the sample. From this figure you must. subtract the absorbed moisture to obtain the free moisture, which is used to adjust the batch.
Saturated surface-dry (SSD): This is achieved under laboratory conditions when all the pores are completely filled with water but no free water remains on the surface of the aggregate. Aggregates in this condition will not contribute free water nor absorb water from the mix.
ASTM C128 - Specific Gravity and Absorption of Fine Aggregate How does one know when SSD has been reached in a sand sample? Condition Using the cone test, tapping the sample 25x in place then removing the cone from the sample, the sample should slump slightly which will conclude that it has reached SSD.
SSD stands for saturated surface-dry. The surface is SSD when the concrete is saturated with water to a depth of several millimeters, but the other surface is devoid of free water, as if it had been dried with a towel.
Specific gravity is the ratio of the solid density of sand particles to the density of water. This determines the proportioning or ratio between cement, aggregate and water. A high specific gravity means that the sand particles are heavier and more densely packed, resulting in a dense concrete mix.
Free moisture means liquid that drains freely by gravity from solid materials. Sample 2. + New List. Free moisture means liquid that drains freely by gravity from solid materials. "
The amount of water is determined by subtracting the dry weight from the initial weight, and the moisture content is then calculated as the amount of water divided by the dry weight or total weight, depending on the reporting method.
Moisture. Relative humidity (RH) is often mistaken for moisture; however, these terms measure two different characteristics of concrete. Moisture content represents the amount of water in liquid form, while humidity levels represent the amount of water in vapor form.
Decreased strength: When relative humidity levels increase, the compressive strength of concrete decreases, affecting its durability. Microbial growth: Moisture creates the ideal conditions for the growth of mold, mildew and bacteria. When mold and bacteria grow and reproduce within concrete, they affect its strength.
aggregate AG-rih-gut noun. 1 : a mass or body of units or parts somewhat loosely associated with one another. 2 : the whole sum or amount : sum total. Examples: The university's various departments spent an aggregate of 1.2 million dollars in advertising last year.
Aggergate Absorption UseAggregate absorption is the increase in mass due to water in the pores of the material. Aggregate absorption is a useful quality because: High values can indicate non-durable aggregate. Absorption can indicate the amount of asphalt binder the aggregate will absorb.
The aggregates should be weighed (Weight 'A'). iv) The aggregates should then be placed in an oven at a temperature of 100 to 110oC for 24hrs. It should then be removed from the oven, cooled and weighed (Weight 'B'). Formula used is Water absorption = [(A – B)/B] x 100%.
In aggregates. Generally, an aggregate has four different moisture conditions. They are Oven-dry (OD), Air-dry (AD), Saturated surface dry (SSD) and damp (or wet).
Readings on a moisture reader will generally range from 5 to 40 percent. A range of 5 to 12 percent is considered optimal. A reading of up to 17 percent is generally considered moderate moisture and acceptable.
DEFINITION. The natural water content also called the natural moisture content is the ratio of the weight of water to the weight of the solids in a given mass of soil. This ratio is usually expressed as percentage.
Usually water content refers to wet basis while moisture content refers to a dry basis. So basically water content = (total weight - dry weight)/total weight and moisture content = (total weight - dry weight)/dry weight.
Any household produces moisture by cooking, washing, bathing and exercising. Even breathing brings moisture into the air. Your family and pets bring many litres of water into your home every day. Moisture can also enter your house from the soil through the basement or crawl space.
Moisture determination is one of the most important and most widely used measurements in the processing and testing of foods. Since the amount of dry matter in a food is inversely related to the amount of moisture it contains, moisture content is of direct economic importance to the processor and the consumer.
The principle of the thermogravimetric method of moisture content determination is defined as the weight loss of mass that occurs as the material is heated. The sample weight is taken prior to heating and again after reaching a steady-state mass subsequent to drying.
Put the sand into a transparent jar, add water to about 50% above the sand level and shake the jar strongly for at least 30 seconds.
- Water & Sand.
- Shake strongly and wait until the water is clear.
- Clay and silt content = 100 * h1 / h2
- Determine weight of wet sand (Q1)
- Heat it.
- Determine weight of dry sand (Q2)
Recommended Values of Specific Gravity and Water Absorption for Aggregates. The specific gravity of aggregates normally used in road construction ranges from about 2.5 to 3.0 with an average of about 2.68. Water absorption shall not be more than 0.6 per unit by weight.
The significance of fineness modulus (FM) is in specifying the proportions of fine and coarse aggregates when designing concrete mixes. The higher the value of FM, the coarser the aggregate. Generally, a lower FM results in more paste, making the concrete easier to finish.
When measuring moisture in concrete, the best and most reliable method is to use the ASTM F-2170 testing method. Under this method, you'll use a thermo-hygrometer with in-situ probes, along with a series of prepared holes, to get readings of relative humidity deep in the concrete slab.
