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Masonry Quiz Chapter 1-6
Terms in this set (68)
How did Romans achieve significant progress in masonry?
discovered Portland cement by mixing flash w/ lime
what are the two main components of portland cement?
lime and flyash
What are the advantages of plain concrete vs. historic masonry?
forming possible, no joints or block cutting, increased speed
what are the phases of formation of concrete?
fresh, setting, hardened
what are the advantages of using steel bars in concrete?
support tensile strength
what are the factors that enforce the compatibility of steel and concrete?
deformed steel bars, shrinking of concrete as it hardens
what are the advantages of using reinforced masonry vs. reinforced concrete?
formwork is not required and decreased construction times/complexity
what are the disadvantages of using reinforced concrete masonry vs reinforced concrete?
lower strength and reduced durability
what is the most important parameter in concrete mix design?
what is the value of the w/c ratio needed for portland cement hydration? Why is higher w/c ratio used in practice?
25%. Facilitates workability by increasing flowability
what are the main types of voids in concrete
3. interconnected air voids
4. isolated air voids
how is protection of concrete against freezing-thawing achieved?
describe the condition of the aggregate within fresh concrete. what term is used to describe this condition?
absorbs water- called transition zone
describe the effect of pozzolans on concrete properties
improve micro-structure of concrete via replacing weak calcium hydoxide
what is the agency responsible for preparing and publishing concrete materials specs?
define concrete workability and describe its method of measurement
what is the difference between required concrete compressive strength (f'cr) and the design or specified concrete compressive strength (f'c)?
f'cr is the anticipated test result average
f'c is for structural design of members
what is the main parameter that determines the mechanical properties of concrete? how is measured based on ASTM?
ACI. ASTM gives standards for materials and testing
why is tensile strength of concrete low?
presence of micro cracks result in sensitivity
what are the methods of testing the tensile strength of concrete?
1. direct tensile strength
2. the splitting tensile strength
3. the bending tensile flexural strength
why is the modulus of rupture of concrete higher than its splitting tensile strength?
concrete is weak in tension
what is the approximate value of drying shrinkage of concrete?
what are the precautions utilized to reduced concrete shrinkage and creep?
1. proper curing
2. decrease mixing water
3. use quality aggregate
4. proper mix design
5. construction joints
6. shrinkage/creep reinforcement
7. higher strength concrete
what are the two main quality control procedures for concrete?
municipality and special
what is the extra quality control procedure used for concrete in cold climates?
air content test
what is the extra quality control procedure used for concrete pavement?
flexural strength or modulus of rupture test
what is zero slump concrete? why is it suitable for block manufacturing?
has no workability. blocks maintain their shape
what are the pozzolans used for block manufacturing? what are their utilization manners?
flyash and slag- both are secondary cementicious material
what is the value of the water/cement ratio used for zero slump concrete? why is it considerably low compared to conventional concrete?
0.2-0.3 for low workability
what are the advantages of lime for concrete blocks?
provides a denser and water resistant product
what are the common types of aggegrate used for light weight CMU?
pumice, cinder, slate, fired expanded shale, expanded slag, expanded clay
what are the common types of aggregate used for normal weight concrete blocks?
limestone, granite, siliceous aggregate
what is the most common block size in construction?
8 x 8 x 16
what are the common types of concrete blocks?
standard, bond beam, open end, open end beam. double open end beam, half/column, lintel, pilaster
what are the most efficient block shapes?
open end- no voids
what is the difference between bond beam blocks and channel blocks?
bond beam has a notched web
what is the difference between nominal and actual dimensions of concrete? what does this represent?
3/8". accounts for mortar joint
what are the three types of pilaster blocks?
Block I, Block II, Corner
what is the defination of precision blocks? list four blocks in addition to precision blocks
untextured, smooth surfaces and precise dimensions
1. split face
4. ground/polished face
what is the ASTM standard that governs block properties?
why are block properties specified by ASTM?
they are considered standard materials
what are the ASTM standard test methods for block properties testing?
2. unit weight
3. water absorbtion
4. compressive strength
what are the important properties of mortar to function as a temp binding paste?
1. water retention
what are the primary constituents of mortar?
lime, sand, cement, water
what is the role of lime in mortar
1. water retention
2. enhance plasticity
3. delay setting
what are the four types of mortar?
M, S, N, O
describe the quality control procedure for mortar
there is none if proportion specs are used
what is the type of mortar used in Socal? why?
S. Has both strength and workability
how is grout different from conventional concrete?
smaller aggregate and higher slump
what are the two types of grout and what conditions are they used for?
Fine- used for spaces 3/8" or less
describe the grout sample used for testing grout strength for masonry construction
4 blocks around on top of special paper
how does one compensate for block absorption of mixing water from grout?
excess water is added to the grout
what are the min compressive strength and slump for grout?
greater than 2000 psi and 8-11 inches
what is the role of wall ties?
seismic and weather strengthening
why is it common for ties to be galvanized?
how does one adjust for misalignment of bed joints in masonry when using wall ties?
adjustable ties are used
what are the two major components of concrete masonry based on volume fraction?
block and grout
why is the compressive modulus of elasticity of concrete blocks practically constant?
what are the factors that affect compressive strength of CMU?
what are two methods for verifying compliance w/ f'm for concrete masonry?
1. component type/strength method
2. prism test method
what are the code requirements for grout compressive strength to assure compliance with f'm utilizing component type/strength method?
exceeds 2000 psi and f'm
what are the limits of of elastic range for concrete masonry in compression?
0-0.33 x compressive strength
what is the equation for concrete masonry compressive modulus of elasticity based on MSJC code?
what is the value of concrete masonry's poisson's ratio?
what is considered the weak link in concrete masonry for tensile bending resistance?
in which direction concrete masonry is stronger under the effect of tensile bending stress?
parallel to bed joints
what are MSJC code equations for shear and modulus of elasticity?
fv= 4 x SQROOT(f'm)
Ev = 360f'm
what is the other term used to refer to shear modulus of elasticity of masonry?
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