Concrete
This is the most widely used construction material for NRCS with a long history of use.
What is concrete?
This type of cement is used for pavements, sidewalks, and reinforced concrete structural members.
Type I
Approximately, 60-80%of the concrete mixture is made up of aggregates. True/False
True
For concrete forming ______________ are used to maintain the wall width specified in the NRCS design.
What are tie rods?
The NEM and Conservation Practice Standards are the primary source of this for NRCS engineering.
What is Policy?
The chemical reaction between water and cement that causes the cement to cure or harden.
What is hydration?
This type of cement is used for large masses concrete structures such as nuclear plants and dams.
Type IV
Very fine sands (aggregate) are uneconomical. True/False
True (pg. 114)
The process of compacting freshly placed concrete in forms and around reinforcing steel to remove air and aggregate pockets.
What is consolidation?
The NEH, and other NRCS trusted sources, is the culmination of decades of knowledge and wisdom for design criteria of structures for farm production and conservation.
What is Guidance?
Binding compound of concrete that is a fine, pulverized material, consisting of compounds of lime, iron, silica, and alumina.
What is portland cement?
What are the three types of air-entrained portland cements?
Type IA, IIA, and IIIA
Sand is graded using a layered set of these with the aid of a shaker.
What are sieves?
Pneumatic placed concrete, sprayed on to a surface with a pressurized system, not using forms.
What is shotcrete?
The online repository for: GM, NEM, NEH, Technical Releases and many other national NRCS documents.
What is eDirectives?
The organization responsible to set standards for concrete by which NRCS engineering design criteria is based on.
What is the American Concrete Institute?
Which air-entrained type cement is high early strength used in cold weather.
Type IIIA
An admixture that speeds up the strength development of concrete.
What is an accelerator?
The process of concrete reaching its specified design strength after 28 days, this is known as _____________
curing
To determine concrete wall thickness and rebar design lateral earth loads need to be determined through criteria described in this well-known NRCS publication.
What is TR74?
During the curing process heat causes a concrete structure first to expand and then to retract as it cools.
What is shrinkage?
Type II cement is used to protect against severe sulfate conditions. True/False
False - It is used for moderate sulfate attack. Type V is used for severe sulfate.
_________ are admixtures that coat the cement particles, causing them to break away from the lumps and disperse in water.
What are superplasticizers?
The minimum rebar spacing for environmental structures.
What is 12 inches? (ACI 350)
The combined action of a group of people, especially when effective and efficient.
What is teamwork?