I acknowledge the support of the Leicester School of Architecture, Faculty of Art and Design, De Montfort University, Leicester, and Professor Brian Ford, School of the Built Environment, University of Nottingham. I am grateful to the building owners, architectural practices and their photographers for the inclusion of the photographs.
INFORMATION SOURCES
General
Units
Chemical symbols
Cement notation
BRICKS AND BRICKWORK
Introduction
Clay bricks
Sand bricks are susceptible to surface damage during handling, exposing the underlying color of the brick. Both the content of the technical literature and the products themselves are subjected to this investigation.
Unfired clay bricks
The thermal conductivity of bricks depends on density and moisture content, but in general clay bricks are poor thermal insulators. However, the application of acoustic plaster or the addition of a free-standing plasterboard panel backed by absorbent material improves impact noise insulation.
Reclaimed clay bricks
Recently, some buildings have been constructed with lime mortar, specifically with a view to the potential recycling of the metric bricks at the end of the useful life of the construction. Of the estimated 2500 million bricks demolished in the UK each year, only around 5% are reclaimed and almost half are crushed and used as hard fill.
Brickwork
When trimming old masonry, it is particularly important to adapt the porosity of the brick to the water retention properties of the mortar. Movement-tolerant wall ties bend or slide in a slot system attached to one leaf of the masonry.
Calcium silicate bricks
However, calcium silicate bricks should not be used as pavers where winter salting can be expected. However, calcium silicate bricks are particularly popular for their light-reflecting properties, for example in light wells or atriums.
Concrete bricks
The thermal conductivity of concrete bricks is equal to that of clay and calcium silicate bricks of similar density. The fire resistance of concrete bricks is of the same order as that of clay and calcium silicate bricks.
BLOCKS AND BLOCKWORK
Concrete blocks
Medium and lightweight concrete blocks are manufactured incorporating a wide range of aggregates, including expanded clay, expanded blast furnace slag, sintered ash and pumice. The textures range from polished, smooth and weathered (sanded or blasted) to striated and split flat (Fig. 2.7), the latter intended to give a random variability more associated with natural stone.
Clay blocks
Light concrete blocks are available in a wide range of colors from white, to buff, sandstone, yellow, to pink, blue, green and black. The glazed blocks are available in an extensive range of durable bright colors and are suitable for indoor or outdoor use.
Gypsum blocks
Unfired blocks made of clay and sometimes with straw can be used for non-load-bearing partitions. Gypsum blocks can be used as non-load-bearing partitions and internal wall insulation.
Blockwork
Ideally, such movement joints should be located at intersecting walls or at other points of structural discontinuity, such as columns. Where masonry is to be applied the mortar should be raked back to a depth of 10mm for additional wedge.
Beam and block flooring
External siding or suspended tiles should be secured to battens separated from the blockwork with a vent membrane. For exterior plastering, a spatter coat must first be applied to dense blockwork, followed by two coats of cement/lime/sand plaster.
Landscape blockwork
BS Code of Practice for the Design and Installation of Damp-Resisting Layers in Masonry Structures. PD CEN/TR Design and use of inserts for lifting and handling of precast concrete elements.
LIME, CEMENT AND CONCRETE
Lime
The carbonation process is slow, as it is controlled by the diffusion of carbon dioxide into the bulk of the material. Hydraulic lime can be used for interior limewashes, and also for fixing glass bricks where a flexible binder with minimum shrinkage is required. The recycling of bricks and blocks is easier due to the lower adhesion of the mortar.
In exposed situations hydraulic lime is used and the thicker initial layer can be reinforced with horsehair.
Cement
Grade 42.5 Portland cement accounts for approximately 90% of total UK cement production. Sulfate resistant Portland cement (BS) is suitable for concrete and mortar in contact with soil and groundwater containing soluble sulfates up to a maximum level (measured as sulfur trioxide) of 2% in soil or 0.5% in groundwater. The composition of the material is generally similar Portland cement as shown in Table 3.9.
However, the ultimate strength of mature concrete is comparable to equivalent Portland cement.
Concrete
Sulfates are often present in the soil, but the rate at which sulfate attacks the concrete depends on the soluble sulfate content of the groundwater. The chemical design class (DC1 to DC4) defines the qualities of the concrete required to resist chemical attack. The degree of creep is largely dependent on the elastic modulus of the aggregate.
The extent of creep can be several times greater than the initial elastic strain of concrete under the same applied load.
Reinforced concrete
This ensures that any tensile force within the concrete is transferred to the steel reinforcement. The shape and condition of the steel surface and the quality of the concrete all affect the bond strength. When the cover exceeds 40 mm, additional reinforcement will be required to prevent spalling of the concrete at the surface.
The tendons are cut at the ends of the beams, whereby the concrete is pressed together.
Visual concrete
Therefore, surface defects must be corrected with fillers before the subsequent assistance and painting of the concrete. Discoloration is reduced by the use of matte coatings, which retain the mold release agent during compaction of the concrete. The number of blow holes is reduced by using less absorbent materials such as wood and polystyrene.
Depending on the size of the grit used and the hardness of the concrete, a range of finishes can be achieved, including sculptural designs.
Concrete components
BS specification for hot-rolled and hot-rolled and worked high-tensile alloy steel bars for prestressing concrete. BS ISO Epoxy powder and sealant for coating steel for concrete reinforcement. BS EN Pigments for coloring building materials based on cement and/or lime.
BS EN Assessment of in-situ compressive strength in precast concrete structures and components.
TIMBER AND TIMBER PRODUCTS
Timber
According to the size and distribution of vessels, hardwoods are divided into two distinct groups. During the seasoning process, the shrinkage of the timber is different in three main directions; moreover, as described in the section "Moisture Movement" (page 115), the outside of the wood tends to dry out faster than the inside. Hardwoods are graded THA or THB (structurally soft hardwoods), TH1 or TH2 (structurally soft hardwoods) or rejected as appropriate. The higher THA and TH1 grades in each category have fewer natural defects, such as knots or slanted grain.) The only class for tropical hardwoods is HS (hard tropical structural hardwood).
Chemical modification of wood involves acetylation of the wood by adding acetyl groups to the free.
Timber products
The BS EN standard specifies six classes of hardboard based on load-bearing capacity and environmental conditions. The BS EN standard defines ten classes of low (L) and high (H) medium density according to load-bearing requirements and environmental conditions. The BS EN standard specifies five grades of softboard based on load capacity and environmental conditions.
SB.HLS Bearing Humid Yellow, yellow green The Euroclass fire performance rating under the conditions specified in BS EN for 9 mm untreated softboard of 250 kg/m3 is Class E, pass for non-floor use and Class EFL-s1 for floors.
Recycling timber
Options for reducing waste include better construction site management and direct recycling, such as in wooden floors. BS Code of practice for wood flooring, wood products and wood-based panel products. BS EN Wood and wood-based materials in external windows, external door leaves and external door frames.
BS EN Wood and wood based materials in exterior windows, interior door leaves and interior door frames.
FERROUS AND NON-FERROUS METALS
Ferrous metals
Normally, universal profiles can be bent to smaller radii than hollow profiles with the same dimensions. The rate of heating of a structural steel section within a fire depends on the severity of the fire and the degree of exposure of the steel. Corner planks of suitable cross-section, with a large part of the steel encased in the concrete floor structure, can achieve a fire resistance of 60 minutes (Fig. 5.14).
The standard sections have a regular trapezoidal profile, where the depth of the section depends on the load and required span (fig. 5.15).
Ferrous alloys
Stainless steel is hot rolled into plate, bar and sheet, while thin sections can be cold rolled. Stainless steel is available in square, rectangular, oval and round hollow profiles as well as standard profiles for structural work. A minimum thickness of 0.4 mm is specified Table 5.8 Stainless steel compositions and grades according to BS EN for different environmental conditions.
In addition to organic coatings, stainless steel can be tern-coated (see tern-coated steel) or galvanized with ≥10 g/m2 tin to BS EN.
Coated steels
Terne-coated stainless steel does not suffer from bimetallic corrosion and can normally be used in contact with lead, copper, aluminum or zinc. Due to the support provided by the steel substrate, lead-coated steel or stainless steel can be used for self-supporting fascias, interior walls, gutters and curved profiles. Cut ends must be protected by brazing in the case of lead-coated steel, although the stainless steel version does not require protective treatment.
Polyvinylidene fluoride-coated zinc/tin-coated (terne) steel or stainless steel is also available in a variety of color finishes that include copper, copper patina, and stainless steel.
Aluminium
