ACI Concrete Strength Testing
Technician CP-19 (14)
These procedures for capping enable concrete cylinders and cores to meet the
standard's requirements for Planeness and perpendicularity.
Equipment needed for the capping process includes capping Plates, alignment devices,
and melting pots.
Plates for neat cement and high strength gypsum plaster caps should be made
of Glass, metal, granite, or diabase.
Sulfur mortar cap plates should be formed against Metal or Stone plates.
The purpose of the guide bar or bull's eye level is to ensure that caps remain
perpendicular to the axis of the cylinder within 0.5 degrees. True.
To avoid accidents during reheating of cooled sulfur, use melting pots that
have Peripheral heating.
The technician should use a stiff layer of Neat cement paste to cap fresh concrete
cylinders.
Hardened concrete cylinders should be capped with High-strength gypsum
paste, neat cement paste, or sulfur mortar.
Plaster of paris and mixtures of plaster of paris and portland cement are examples of
suitable high strength plasters. False.
Sulfur mortars and high-strength gypsum cement cubes must demonstrate a minimum
compressive strength of 35MPa (5000 psi) or the cylinder strength, whichever is
greater.
, The cement paste should be applied to the freshly molded cylinder from 2 to 4 hours
after molding. This is to allow for settling of the concrete specimen.
The strength of the paste depends on:
a) the water-cement ratio
b) time
c) the equipment used
d) type of cement
a, b and d.
A slight twisting action will help eliminate Excess paste and air voids when the capping
plate is placed onto the mound of the paste.
Neat cement paste caps should not be used on dry specimens because the caps
may Shrink and crack when dry.
The technician should remove all Oily or waxy materials from the ends of hardened
concrete cylinders before capping.
Empty the pot and recharge with fresh material at intervals to insure that the oldest
material in the pot has not been used more than 5 times.
When capping concrete cylinders with a compressive strength of 35 MPa (5000 psi) or
greater, it is permitted to reuse compound recovered from the capping operation of old
caps. False.
To avoid Foaming, the sulfur mortar should be dry when it is added to the pot. It should
be kept away from water when heating.
The melting pot for the sulfur mortar must be located under a Hood with an exhaust
fan for ventillation.
Hydrogen sulfide gas, which may be produced during capping, may
be Lethal, nausea, stomach distress, dizziness, headache, irritation of the eyes.
Technician CP-19 (14)
These procedures for capping enable concrete cylinders and cores to meet the
standard's requirements for Planeness and perpendicularity.
Equipment needed for the capping process includes capping Plates, alignment devices,
and melting pots.
Plates for neat cement and high strength gypsum plaster caps should be made
of Glass, metal, granite, or diabase.
Sulfur mortar cap plates should be formed against Metal or Stone plates.
The purpose of the guide bar or bull's eye level is to ensure that caps remain
perpendicular to the axis of the cylinder within 0.5 degrees. True.
To avoid accidents during reheating of cooled sulfur, use melting pots that
have Peripheral heating.
The technician should use a stiff layer of Neat cement paste to cap fresh concrete
cylinders.
Hardened concrete cylinders should be capped with High-strength gypsum
paste, neat cement paste, or sulfur mortar.
Plaster of paris and mixtures of plaster of paris and portland cement are examples of
suitable high strength plasters. False.
Sulfur mortars and high-strength gypsum cement cubes must demonstrate a minimum
compressive strength of 35MPa (5000 psi) or the cylinder strength, whichever is
greater.
, The cement paste should be applied to the freshly molded cylinder from 2 to 4 hours
after molding. This is to allow for settling of the concrete specimen.
The strength of the paste depends on:
a) the water-cement ratio
b) time
c) the equipment used
d) type of cement
a, b and d.
A slight twisting action will help eliminate Excess paste and air voids when the capping
plate is placed onto the mound of the paste.
Neat cement paste caps should not be used on dry specimens because the caps
may Shrink and crack when dry.
The technician should remove all Oily or waxy materials from the ends of hardened
concrete cylinders before capping.
Empty the pot and recharge with fresh material at intervals to insure that the oldest
material in the pot has not been used more than 5 times.
When capping concrete cylinders with a compressive strength of 35 MPa (5000 psi) or
greater, it is permitted to reuse compound recovered from the capping operation of old
caps. False.
To avoid Foaming, the sulfur mortar should be dry when it is added to the pot. It should
be kept away from water when heating.
The melting pot for the sulfur mortar must be located under a Hood with an exhaust
fan for ventillation.
Hydrogen sulfide gas, which may be produced during capping, may
be Lethal, nausea, stomach distress, dizziness, headache, irritation of the eyes.
