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A pinhole occluder is an opaque disk with one or more small holes through it, used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such as myopia. Because light passes only through the center of the ...
Concrete is poured around these plastic forms to create internal voids in the slab A voided biaxial slab installation in Turkey. Voided biaxial slabs, sometimes called biaxial slabs or voided slabs, are a type of reinforced concrete slab which incorporates air-filled voids to reduce the volume of concrete required.
The derivation of the maximum arching moment of resistance of laterally restrained concrete bridge deck slabs utilised Rankin's [21] idealised elastic-plastic stress-strain criterion for concrete, valid for concrete cylinder strengths up to at least 70N/mm 2, which he had derived on the basis of Hognestad, Hanson and McHenry's [23] ultimate ...
A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel- reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving ( see below ).
They stop the bridge from bending out of place in extreme conditions, and also allow enough vertical movement to permit bearing replacement [1] without the need to dismantle the bridge expansion joint. There are various types, which can accommodate movement from 30 to 1,000 millimetres (1.2 to 39.4 in), including joints for small movement ...
In civil engineering, concrete leveling is a procedure that attempts to correct an uneven concrete surface by altering the foundation that the surface sits upon. It is a cheaper alternative to having replacement concrete poured and is commonly performed at small businesses and private homes as well as at factories, warehouses, airports and on roads, highways and other infrastructure.
A bughole (or pinhole) is a small hole in the surface of a concrete structure caused by the expansion and eventual outgassing of trapped pockets of air in setting concrete. [ 1 ] [ 2 ] [ 3 ] Bugholes are undesirable, as they may compromise the structural integrity of concrete emplacements.
Lift slab construction (also called the Youtz-Slick Method) is a method of constructing concrete buildings by casting the floor or roof slab on top of the previous slab and then raising (jacking) the slab up with hydraulic jacks. This method of construction allows for a large portion of the work to be completed at ground level, negating the ...