The degree of saturation is the ratio of the volume of water in a soil to the volume of voids. $latex S = \frac{V_w}{V_v}\times 100\%\newline\newline =\frac{V_w}{V_g + V_w}\times 100\%&s=2$ Where: S = Degree of Saturation Vw = Volume of water (m3 or ft3) Vv = Volume of voids (m3 or ft3) Vg = Volume of […]
How to Calculate Moisture Content
December 13, 2013 by Leave a Comment
The moisture content of a soil is the ratio of the mass of water in a soil to the mass of solids. $latex n = \frac{m_w}{m_s} \times 100\%&s=2$ Where: mw = Mass of water (kg or lbs) ms = Mass of solids (kg or lbs) The moisture content is thus a ratio which can be […]
How to Calculate Soil Porosity
December 12, 2013 by Leave a Comment
The soil porosity, also called the void fraction, is the ratio of the volume of voids (open spaces, i.e. air and water) in a soil to the total volume. $latex n = \frac{V_v}{V_t}\newline\newline =\frac{V_g + V_w}{V_g + V_w + V_s}&s=2$ Where: Vv = Volume of voids (m3 or ft3) Vt = Total Volume (m3 or […]
Concrete Slump: Explanation, testing and Interpretation
December 6, 2013 by Leave a Comment
Concrete slump is a definition of the consistency, often called workability, of concrete. Slump Test The slump test is defined by ASTM C143 and AASHTO T119 in the United States, and EN 12350-2 in Europe. There is no significant other testing method for concrete workability in industry use today. A standard size cone (Base diameter […]
How to Design Guardrail
November 29, 2013 by Leave a Comment
The design guidelines for all barriers is taken from the AASHTO Roadside Design Guide. Determining if Guardrail is Required It is necessary to calculate a “clear zone” which is a distance from the pavement edge within which there should be no hazards. If a non-breakaway appurtenance must appear within the clear zone, a barrier is […]
How to Calculate the Water Cement Ratio
November 28, 2013 by Leave a Comment
The water to cement ratio is the most important factor in concrete strength. The ratio is, as it’s name implies, the ratio of water to cement. $latex w/c\: ratio = \frac{weight\: of\: water\: (lbs)}{weight\: of\: cement\: (lbs)}&s=2$ If you can measure the volume of water, a common conversion is: $latex Weight\: of\: Water\:(lbs)\: =\: 8.33\cdot […]
Water Reducing Admixtures
November 27, 2013 by Leave a Comment
Water-reducing admixtures reduce the quantity of water required to produce concrete of a certain slump. They also: Reduce the water-cement ratio Reduce cement content increase slump Typically, water reducing admixtures reduce the water content by approximately 5 – 10% for the same strength properties. Effect on Strength Generally, an increase in strength is obtained with […]
Air Entraining Admixtures
November 26, 2013 by Leave a Comment
Air entraining admixtures, as you can probably guess, force air into the concrete. They result in microscopic air bubbles spread relatively evenly throughout the concrete. Reasons for Using Air Entraining Admixtures There are several reasons to have air entrainment in concrete: To improve freeze-thaw resistivity To increase resistance to de-icing chemicals To enhance the workability […]
Types of Concrete Admixtures
November 25, 2013 by Leave a Comment
Admixtures are used in almost any concrete mixture produced today. Following is a list of the most common ones: Accelerators When you need fast strength gain because other components require construction adjacent to the concrete. Accelerating admixtures shorten the setting and early-strength development time. They consist of Calcium chloride, Triethanolamine, sodium thiocyanate, calcium formate, calcium […]
Concrete Strength Factors
November 22, 2013 by Leave a Comment
The compressive strength of concrete is expressed in Megapascals (MPa) or pounds per square inch (psi) at an age of 28 days. Since the strength is constantly increasing, the reference strength chosen by industry is 28 days. Typical strengths are in the range of 25 – 35 MPa (3,600 – 5,000 psi). On my bridge […]