Curing CMUs

Heat of Hydration

Low Pressure Steam Kiln

Autoclaving

Configuration and design of curing

chambers• Sample Layout – Individual Atmosphere Chambers with

moving rack system

Configuration and design of curing

chambers

• Sample layout – Single Atmosphere large room

system

SUBJECTS TO BE COVERED

1). STEAM CONDITIONS

2). CURING CYCLE

3). KILN DESIGN

4). BOILER SELECTION

CONTROLLED CONDITIONS

OF STEAM

1). Quantity

2). Quality

3). Velocity

Quantity - Have the required boiler

capacity to produce enough steam to

complete the curing cycle.

Quality - Saturated steam is a quality

steam, having the correct amount of heat

& moisture present.

Velocity - Correct piping to induce

steam evenly into kilns for equal

distribution.

Rate of Temperature Rise of

Block Should be About:

60 deg. F or 33.3 deg. C/ hr.

5.5deg.C /10 min.or 33.3deg.C/hr

EQUILIBRIUM

TEMPERATURE WILL VARY

WITH:

1). Type of Block

2). Material

3). Kiln Size

4). Rate of Temperature

Rise

5). Weather

6). Kiln Insulation

AFTER SHUTTING OFF STEAM, BLOCK SHOULD BE ALLOWED

TO SOAK 6 TO 8 HOURS.

The soaking period is as important as the steam time. The longer the

units are allowed to soak the better will be the final results. As long

as the air in the kiln is not disturbed, the humidity of the kiln increases

as the temperature decreases, because the moisture content is relatively

constant. An accelerated curing condition is maintained in the kiln

during the entire time the temperature is falling to 70 degrees (21.11c).

Therefore, the longer soaking period is extended, the greater the

compressive strength of the block.

DETERMINATION OF

BOILER LOAD

1). Individual kiln requirements

2). Number of kilns being operated simultaneously

3). Plant heating requirements

4). Miscellaneous loads

In conclusion it must be remembered that the

proper curing of concrete masonry is a processing

problem and not a heating problem. The proper

installation of a efficient curing system is the job of a

person thoroughly familiar with the thermodynamic

properties of steam and air, and also familiar with

boilers, preheating and water treatment.