The building site is roughly square in shape, the building had a playground-courtyard in the middle and an high
Colonnade surrounded by shops along the perimeter facing Calles Galiano, Reina, Aguila, and Dragones. The ground floor was commercial, the upper floors were occupied by the residences of some 200 families. slabs are today rare and have limited practical applications, with one exception being the mud slab. They were once common, but the economic value of reinforced ground-bearing slabs has become more appealing for many engineers. Since unreinforced concrete is relatively very weak in tension, it is important to consider the effects of tensile stress caused by reactive soil, wind uplift, thermal expansion, and cracking. One of the most common applications for unreinforced slabs is in concrete roads. Mud slabs, also known as
rat slabs, are thinner than the more common suspended or ground-bearing slabs (usually 50 to 150 mm), and usually contain no reinforcement. This makes them economical and easy to install for temporary or low-usage purposes such as subfloors, crawlspaces, pathways, paving, and levelling surfaces. In general, they may be used for any application which requires a flat, clean surface. This includes use as a base or "sub-slab" for a larger structural slab. On uneven or steep surfaces, this preparatory measure is necessary to provide a flat surface on which to install rebar and waterproofing membranes. In this application, a mud slab also prevents the plastic bar chairs from sinking into soft topsoil which can cause
spalling due to incomplete coverage of the steel. Sometimes a mud slab may be a substitute for coarse
aggregate. Mud slabs typically have a moderately rough surface, finished with a
float. Before the development of effective methods of
steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron. It was given the name
wrought because it was hammered, rolled or otherwise worked while hot enough to expel molten slag. The modern functional equivalent of wrought iron is
mild steel, also called low-carbon steel. Neither wrought iron nor mild steel contain enough carbon to be hardenable by heating and quenching. Wrought iron is highly refined, with a small amount of slag forged out into fibres. It consists of around 99.4% iron by mass. The presence of slag is beneficial for blacksmithing operations, and gives the material its unique fibrous structure. The silicate filaments of the slag also protect the iron from corrosion and diminish the effect of fatigue caused by shock and vibration. Historically, a modest amount of wrought iron was refined into
steel, which was used mainly to produce
swords,
cutlery,
chisels,
axes and other edged tools as well as springs and files. The demand for wrought iron reached its peak in the 1860s, being in high demand for
ironclad warships and
railway use. However, as properties such as brittleness of
mild steel improved with better
ferrous metallurgy and as
steel became less costly to make thanks to the
Bessemer process and the
Siemens-Martin process, the use of wrought iron declined. Many items, before they came to be made of
mild steel, were produced from wrought iron, including
rivets,
nails,
wire,
chains,
rails,
railway couplings,
water and steam pipes,
nuts,
bolts,
horseshoes,
handrails, wagon tires, straps for timber
roof trusses, and
ornamental ironwork, among many other things. Wrought iron is no longer produced on a commercial scale. Many products described as wrought iron, such as
guard rails,
garden furniture and
gates, are actually made of mild steel. They retain that description because they are made to resemble objects which in the past were wrought (worked) by hand by a
blacksmith (although many decorative iron objects, including fences and gates, were often cast rather than wrought). ==Vendors==