![]() ![]() the force of the weight is straight down. First, the load is considered to be a pullout or tension load, i.e. An object placed overhead is critical for a number of reasons. Where the object is placed is a major consideration due to the different load values. Is it overhead on a wall or fastened to the floor into concrete? The difference in these minimum embedments results in a stronger holding value for the 3/4" concrete anchor in comparison to the holding value of the 1/4" anchor. For example, a 3/4" diameter anchor has a minimum embedment of 3-1/4" and a 1/4" anchor has a minimum embedment of 1". The larger the diameter- the higher holding values the anchor will have. The best holding values are achieved when the concrete is hard and the embedment into the concrete is deep. In most cases- it is the concrete that fails, not the anchor. The weakest link of a concrete anchor is the concrete in which it is placed. It is important to determine the diameter of the anchor needed from the weight of the object to be fastened to the concrete. Increased holding values will also be attained when the working end of a concrete anchor is on the far side of rebar. Generally, the deeper the embedment of a concrete anchor, the better the pullout/holding values will be. While these special rebar bits work well, they are fairly expensive and add extra work when placing anchors. There is special rebar cutting bits that can be used when rebar is located in areas where the anchor must be placed. The rebar may get in the way when trying to place a concrete anchor deeply or it may cause problems when drilling a hole. This will create an unsupported edge which will reduce the holding values of the concrete anchors.Ĭoncrete reinforced with rebar may cause problems. ![]() It is important to avoid having the working end of the concrete anchor too close to the bottom of the concrete. It makes sense then that the larger the diameter- the larger the minimum embedment. As a rule of thumb, the smaller the diameter- the shorter the minimum embedment will also be. There is a minimum embedment with all concrete anchors which is determined by the diameter of the anchor being used. Standard concrete is less than 7,000 psi and high strength concrete is measured between 7,000 and 14,500 psi. For example, concrete that is designated as 3,000 psi concrete is concrete that is able to carry a compression stress of 3,000 psi after 28 days. The measurement is calculated by pouring concrete in a cylinder and then measuring the force needed to break the concrete after it is hardened. The compression strength of concrete is measured in psi, or pounds per square inch. What is the compression strength of concrete? A specific concrete anchor or fastener may not work in all applications. However, the reason there are a variety of concrete fasteners is that a variety of concrete also exists. Most other concrete fasteners will successfully work in concrete regardless of age. Tapcon® screw may not work in extremely old concrete because the lead threads deteriorate and prevent the screw from being inserted the minimum of one inch. In some cases, concrete also becomes more abrasive as it ages. The older the concrete, the harder it gets and therefore the more difficult to drill into. ![]() Green concrete, which is less than 28 days old, should not be drilled or anchored into. The truth is that only concrete sidewalks and mixers exist! People wrongly call sidewalks "cement" and point out "cement trucks" and "cement mixers". The hydration hardens the concrete for years, which means that concrete gets stronger as it ages. The cement and water harden and bind the aggregates into a solid mass over time through a process called hydration. Portland cement is not a brand name but rather a generic term for the type of cement used in most concrete. Concrete is a mixture of water, aggregates (i.e. The words "concrete" and "cement" are often erroneously used as interchangeable terms. ![]() What is the difference between cement and concrete? Purchase Anchors What is the base material? ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |