INSTRUCCIONES GENERALES DE OPERACIÓNINSTRUCCIONES GENERALES DE OPERACIÓN Fabricantes Manual D-3...

INSTRUCCIONES GENERALES DE OPERACIÓN

Fabricantes Manual Sección D 10-AUG

Instrucciones Generales de Operación D-1

Haciendo las corridas de las camas D-4

Limpieza final D-6

TROUBLESHOOTING

STRAND SLIPPAGE D-9

STRESS CRACKING D-18

SHRINKAGE CRACKING D-18

LONGITUDINAL CRACKING D-19

LINES, CRACKS ON SIDES OF PRODUCT D-20

HORIZONTAL CRACKING - (END SHEAR) D-21

BOTTOM WEB VARIATION D-24

SIDE TEARING AND PULLING D-26

WEB TEARING/COLLAPSE D-27

BATCH PLANT RECOMMENDATIONS D-30


Fabricantes Manual Sección D 10-AUG


Fabricantes Manual D-1 10-AUG

INSTRUCCIONES GENERALES DE OPERACIÓN 1. Despues de que la máquina ha sido configurada de acuerdo a los ajustes

preliminares recomendados. La extrusora y el carro son asegurados en una de las posiciones predefinidas del caballete. Esto posiciona apropiadamente el extrusor para moldear la cama deseada.

2. La extrusora es posicionada en la cama de forma tal que la parte trasera del molde esté enfrente de los pernos tensores.

3. Entonces se baja lentamente la extrusora de manera que la parte trasera de los marcos este aproximadamente a 1/16" (1.5mm) sobre el nivelador, o sobre la losa anterior. La experiencia del operador determinará los ajustes propios de su planta.

4. Los compactadores frontales, A y B (vea pagina C-2), son atornillados en posicicion y se debe de revisar perfectamente para los ajustes de aproximación. Si no se requiere un cable superior, los compactadores A y B son atornillados en posición para poder bajar la máquina.

Guía de Cable

5. El cable guía se baja a su posición correcta. El cables se acomoda en los

lugares apropiados en la guía y la correa de acero se inserta para

sostener o colocar el cables. Revise perfectamente (con una regla) la

altura del cables.



6. Antes de mover la máquina en reversa, hacia la posición inicial,

asegurese de que los Nucleos libren todos los bloques y fijadores de los

cables. Entonces, lentamente mueva la máquina en reversa, hasta que la

cara posterior de la Tolva Medía, esté adyacente a la cara exterior de los

Batientes.

7. Llene todas los tolvas con material, primero accione todos los

mecanismos de la extrusora y despues ponga al caballete en movimiento.

En algunas máquinas, la máquina en su totalidad puede pararse al

presionar alguno de los botones de Alto de la extrusora o del caballete o

jalando el hilo de "E-Stop" (Paro -Alto- de emergencia)

8. En este momento observe los compactatadores y el flujo de materiales al

tener algunos pies de alto antes de hacer cualquier ajuste. Se recomienda

que durante este periodo se hagan una serie de revisiones, incluyendo,

pero no limitándosea a las siguientes:

a. Asegurese de que las compuertas de las Tolvas estén abiertas.

b. Detrás del compactador B y frente a los Nucleos, revise el alto del concreto compactado. Esto puede hacerse mientras la máquina esta funcionando.

Caer el Agua del Múltiple



c. Revise el flujo de agua sobre el cables que está entre los

compactadores B y A,también debe de revisar el sistema de

goteo de agua.

Tubos de goteo de agua

d. Determinar si la línea del bisel del marco esta lo mas abajo

posible acercandose al nivelador o losa inferior sin tocarlas.

e. Vigile el flujo del material de hasta abajo en el Compactador A y haga los ajustes necesarios con la llave (rueda) de ajuste.

f. Vigile el flujo del material de enmedio y haga los ajustes

necesarios con la rueda de ajuste en la llave de paso de enmedio.

g. Si el material se está abultando frente al Compactador E, baje el

compactador D. No intente cambiar de posición (subir) el E, de otra manera el espacio superior será muy delgado. Despues de ajustar el D, será necesario bajar también el Compactador C. Si despues de bajar el Compactador C, hay abultamiento excesivo frente al Compactador C, cierre la llave de paso.

h. Asegurese de que todos los compactadores toquen el concreto.

Hay una tendencia de los operadores de tener el Compactador E tan alto que nunca tocará el concreto. En este caso, deberá bajar el compactador E de manera correcta, para permitir que toque el concreto lo suficiente para cerrar las aperturas causadas por los



sostenedores del núcleo. Vea la ilustración en la página d-2, o vea tambien la "Tabla de síntomas, problemas y soluciones"

i. Revise la cantidad de mezcla superior entre las paletas F y G y haga los ajustes necesarios subiendo o bajando la paleta F.

j. Las revisiones mencionadas deben de ser hechas periodicamente durante cada corrida para asegurar la uniformidad y calidad requerida.

k. Se deberán hacer revisiones periódicas del cable guia para determinar si los cables están en posición y altura correctas.

l. Tambiéne deberá revisar periodicamente la altura, superior e inferior de cada losa.

m. Una supervisión constante sobre la parte superior de la máquina para determinar que el nivelador o la losa moldeada arriba esta limpia y seca. Esto se puede lograr usando un chorro alimentado por un compresor de aire para quitar cualquier basura. A pesar de que esto parezca relativamente sin importancia, esto mejorará la apariencia de la losa que se esté moldeando. No moldee una losa sobre una cama mojada ya que de ser asi, la losa se pegará con la inferior.

HACIENDO LAS CORRIDAS DE LAS CAMAS

Es imporante que al terminar una corrida, haga los siguientes pasos pare evitar problemas innecesarios:

1. Asegurese de que los cables guía son levantados aproximadamente a 20 pies (6 metros) de los pernos tensores.

2. Asegurese que el camino esté libre de obstrucciones frente a la máquina.

3. Asegurese que la máquina este posicionada apropiadamente para poder librar los batientes.

4. Cierre las compuertas la tolva inferior.

5. Cierre las compuertas de la tolva superior.

6. Cierre las compuertas de la tolva de enmedio.



7. Si no hay cables superior en la losa, la máquinaria se quedará sin cama en los Compactadores inferiores que faltan.

8. Si hay cables superior en la losa, pare la máquina completamente, lo suficientemente alejado de los batientes para dejar suficiente espacio para quitar los compactadores inferiores.

9. Comience con el proceso de limpieza inmedíatamente despues de terminar una corrida, prestando particular atención a lo siguiente:

d. Limpie el concreto de la parte superior de los Núcleos y de los

sostenedores de los núcleos con un raspador de acero.

e. Limpie dentro de los marcos con una estopa o con un estropajo de acero.

f. Limpie los Compactadores y las Paletas con una estopa o con un

estropajo de acero.

g. El proceso de limpieza al finalizar una corrida no debe tomar mas que algunos minutos.

10. Vuelva a posicionar y fije la máquina sobre la siguiente cama a moldear

inmedíatamente después de terminar una corrida. 11. Baje la máquina a la altura correcta para librar las placas tensoras. Mueva

lentamente a traves de los batientes y despues regrese rápidamente a su posición inicial.

12. Siga los procedimientos de configuración como fue establecido anteriormente.

13. Si se requiere algun cambio entre las losas, será necesario vaciar el extrusor de todo material para prevenir el endurecimiento del concreto en las tolvas. Y a continuación siga el siguiente procedimiento:

a. Limpie la máquina.

b. Configure la máquina.

c. Acomode o baje la máquina a la siguiente cama.

NOTA: Se requiere de generar una buena base de experiencia entre cada

moldeado para determinar la conveniencia de usar material residual en la siguiente losa y no requerir un cambio.



LIMPIEZA FINAL Al terminar la última corrida de losa del día, se deberá prestar mucha atención a la limpieza de la máquina. Se recomienta que se establezca y siga un procedimiento definitivo para asegurar una limpieza completa y apropiada así como para realizar esta función de la manera más eficiente. Para ayudarlo en esta importante operación, sugerimos seguir el siguiente procedimiento que ha probado ser satisfactorio.

1. La limpieza de la máquina debe ser un esfuerzo en equipo incluyendo al operador de la máquina y al operador del caballete. El generar un hábito de limpieza apropiada hace el trabajo mucho mas fácil

2. Inmedíatamente despues de completar la ultima corrida del día, deberá tirarse todo el concreto sobrante de las tolvas en las cubetas que están al final de la cama.

3. El operador del caballete deberá limpiar dentro de las tolvas. Para lograr un trabajo completo, será necesario que el operador se incline dentro de las tolvas, y usando un raspador, estopa o un estropajo de acero limpiar el interior de la tolva. NO use martillos dentro de las tolvas.

4. Despues de limpiar las tolvas, el operador del caballete deberá reunirse con el operador de la máquina para realizar el siguiente procedimiento:

a. Con una estopa seca o estropajo de acero, Saque todo el concreto suelto dentro de los compactadores, núcleos, moldes y tolvas. Los pedazos grandes de concreto que se formen en las esquinas de las tolvas y alrededor de los compacatores, asi como en cualquier otro lado deberán ser removidos con un raspador de acero. Las partes mas duras podran ser quitadas con un cincel y un martillo de tal manera estos golpes hagan desprender o pelar el concreto solidificado, y no tratar de eliminarlo a golpes directos del martillo.

b. Remueva la tolva pequeña usada para la mezcla superior y limpie completamente. El quitar esta tolva tambien facilitará la limpieza apropiada de las paletas y el área entre ellos.

c. Toda máquinaria incluyendo la máquina SPANCRETE® , está

sujeta a desgaste y raspaduras y requiere reparación o reemplazo de las partes dañadas.



Todas las partes móviles, incluyendo los fijadores y los bujes, deben de ser lubricados en intervalos regulares. todos los compartimientos para grasa y tapas de aceite necesarios son proveidos. También se recomienda que todas las superficies que tienen contacto con el concreto sean rociadas con algun buen aceite lubricante. Se deberá tener especial cuidado en no engrasar de mas los soportes o motores. Podrá encontrar comentarios extra acerca de este tema en la sección de mantenimiento.

d. Se recomienda ampliamente que no use agua para limpiar la máquina por las siguientes razones:

1. El agua puede filtrarse hacia los motores electricos y causar graves daños.

2. Las particulas sueltas de arena o cemento llegarán a los soportes, bujes, soportes del motor u otros, causando fallas prematuras.

3. Incluso si usted es cuidadoso en el secado de su máquina, habrán ciertas zonas que no podrá secar completamente, causando oxidación y finalmente fallas.

4. Si la máquina es lavada, deberá secarse completamente y cubrir todas las partes de la máquina que entren en contacto con el concreto de aceite de motor o algun agente de eliminación de concreto similar basado en aceite.

e. No permita la acumulación de concreto endurecido, y si es asi,

remuevalo con raspadores y/o cinceles, no use un martillo directamente para aflojarlo.



f. Limpie las cubetas de concreto usadas para alimentar de material

a la máquina, especialmente en el área de los dientes. La limpieza apropiada de las cubetas asegurará una apertura fácil de éstas. Cuando el material sea transportado por un montacargas, se sugiere que el operador del montacargas sea el responsable de esta función.

g. Revise la máquina buscando partes flojas para preparar la máquina para el siguiente día de producción. Preste especial atención al soporte central de la almohadilla del bloque del eje del oscilador, si este soporte se afloja, el eje del oscilador puede doblarse.

h. Haga un cambio si es necesario, o revise para los ajustes necesarios en los espaciadores del nucleo, molde, etc..


SOLUCIÓN DE PROBLEMAS


Strand Slippage

Bonded Strand After the Strand is de-

tensioned, you will notice some

of the wires in the Strands have

“curled up”.

First signs of bonding

Fixture for marking Strand

Quality Control typically

paints an area near the entry

point of the Strand and

records how much initial

slippage has occurred

throughout the bed.

Ideally, during de-tensioning,

both ends of the Casting Bed

are cut simultaneously in the

same pattern described

elsewhere in this Handbook.




Poorly Bonded Strand Because the direction of strand movement will vary, always look at both ends of a piece to determine slippage.

Normal Strand Slippage per PCI Standards 270k 7-wire Strand

Strand

db 3/8” / 9mm 1/2” / 13mm Jacking % fpu

60% 1/32” / 0,8mm 2/32” / 1,6mm

62.5% 2/32” / 1,6mm 2/32” / 1,6mm

65% 2/32” / 1,6mm 2/32” / 1,6mm

70% 2/32” / 1,6mm 3/32” / 2,4mm

Based on: 5% Initial Loss 20% Total Loss Es = 28500 ksi

See PCI Manuals for total report and procedures that can be used to evaluate plank capacity when strand slip is excessive.

Because this type of failure is structural in nature, Strand slippage in finished

product must be evaluated carefully to determine whether or not the product is

useable or should be disposed of as scrap.




Troubleshooting De-bonding and Slippage issues Before evaluating the machine settings, examine the following areas:

Possible Cause Action / Solution

Contaminated Strand Clean or dispose of contaminated Strand

Dry Mix Correct Batching formula and System

Too little/Too much cement in mix Check Batch Scaling

Improper Strand Bond Breaker Application

Evaluate bed layout / procedures

Premature De-tensioning Check QC Records/Break Tests

Overstressed Strand Examine Stressing unit/records

Oversized Strand Verify Engineering specifications




Slippage Problems Related to Machine Set-Up / Adjustments


Improper Strand Height • Adjust Height of Strand

Improper Blocking/centering at plates • Use Strand standoffs,

• Check height of Stressing Plates.

Bottom Tamper / Wire Guide slots Striking Strand

• Center Wire Guide properly

• Verify Strand position

• Adjust Mid-bed wire guides if used.

• Check center points on machine for parallel.

Strand not in proper position • Center Strands Properly**, Double

check Pouring Kit and Prints for accuracy.

Scratcher Rubbing Strand • Check Strand height, Scratcher

length

Improper Scratcher Setting • Lower or raise Scratcher

Middle Tamper Striking Top Strand • Adjust Tamper height/clean buildup

Machine Speed too Fast • Water unable to keep up

Improper Water Drip Rate –Too much or Too little

• Adjust as needed

Improper concrete feed amount. (Not enough material on top of Strand)

• Adjust Flowgate.

• “Notching” Flowgate above top Strand may be necessary to allow more feed on Strand.

• Scalloped Flowgates are another option.

Inadequate Compaction • Adjust Flowgates,

• Adjust “E” Tamper to fill voids caused from Scratcher.

Too Little Vibration (Top Strand) • Inspect Vibrator.




Top Strand Scratchers A Scratcher bar is added to the Oscillator to create a furrow in the concrete that has been deposited by the Middle Hopper and then compacted by the 1st Middle Tamper. The furrow allows water from the Top Strand Watering Bar to reach the Strand.

As you can see, the Scratchers are very close to the Strand. Between 1/8” – 3/16” (3-5mm) from Strand is ideal.

Scratchers

BETTER PHOTO NEEDED

BETTER PHOTO NEEDED




TYPICAL TOP STRAND PRODUCTION SET-UP

1. Correct Strand placement begins prior to stressing the Strand.

a. Be sure that the strand template or marking stick used to place

strand, corresponds with the centerline and set-up of the machine

and cores.

b. The Wire Guide must also be centered correctly.

Wire Guides are centered using cross-sectional prints showing Strand placement.

Measure from the center point of the mounting bar to the center of the Strand notch-outs to correspond with the print. Marks can be made on the Wire Guides and Mounting Bar to

make centering an easy task after the first set-up.

c. Incorrectly aligned Top Strand will cause material to build-up

behind rear Tamper and result in bonding issues. The 6” (150mm)

product is especially vulnerable to centering top strand placement

between the cores.

2. At the front of the machine, the bottom of the Top Strand will be set

between 1/8” – 1/4" (3.2mm - 6.4mm) above the specified location for the

Top Strand. The extra height is based on how much a Strand typically

settles after it passes through the machine. *Be sure that the machine is

set at production height.




3. You may have to lower the Strand slightly to avoid Scratcher interference.

Always check height with print.

4. Tampers may need to be adjusted to avoid hitting Top Strand during

production.

5. Make sure that the Scratcher is lining up with Strand.

6. Verify that Water Line drips are directly above with Strand and flowing at

the correct rate for the speed of production.

7. Bleeding the air out of Water Lines prior to startup, or restarts.

Checking bond of Top Strand while producing:

• After it passes through the finish Troweler, use a margin trowel to expose

and observe Strand. You should see visible moisture starting to form

around each Strand. Also watch for movement in Strand. If the Strand is

moving, check for interference with tamper or scratcher.

• Feel the Top Strand with your margin trowel for Strand movement

• If too much puddling or air bubbling is occurring around the Strand,

decrease water to prevent “washing out” or tear-dropping beneath Strand.

Checking Bottom Strand bonding: • Ensure that the Water Line drips are in line with Strand. If running double

strand, ensure that an individual drip is used for each Strand or that the

drip is centered between the Strands and flowing adequately.

• Adequate material cover must be over strand. 1/2" (12.5mm) to 3/4"

(19mm) of cover prior to vibration is normally enough. After the pan

vibrator passes over, the strand should have about of 1/8” (3mm) of cover

and be centered in slurry.

How to Determine Correct Strand Height




• Bottom - Measure the distance from the Casting Bed to the bottom of the

Strand. If the bottom Strand height specification is 1” (25mm), the Wire

Guide can be set at 1-1/8” (29mm) to compensate for settling. If using a

blocking method to hold up Strands, a slightly larger block is used to

compensate for settling. NOTE: If transverse re-bar is being used, be

sure that the cores have enough clearance as they pass over the re-bar.

• Top - Measure the distance from the Casting Bed to bottom of the Strand.

Adjust the Top Strand vibrating bar to desired height, keeping in mind the

1/8” (3,2mm) settling factor, and the diameter of the Strand. Verify that the

machine is at the proper production level.

Cores rubbing on

rebar.




• Topping Strand for Insulated Wall Panel - Strand height for Insulated

Wall Panel Topping is set in place according to print by the layout crew.

Factors such as insulation thickness, total Panel thickness and whether or

not there are reveals are taken into consideration.

Topping Strand is used with Insulated Wall Panel for exterior layer (Wythe)




Stress Cracking

Transverse Cracking Possible Cause Action / Solution

Poor Quality Cement • Check and Adjust

Improper Curing Procedure • Adjust curing procedure to speed of

moisture loss.

Curing to Long • Beds should be de-tensioned as soon as

adequate PSI strengths allow.

Improper De-tensioning Procedure • Check procedure

Cracks in Casting Bed / Settling in Base Slab

• Fill cracks and grind smooth.

• Re-pour Casting Bed with proper curing procedure.

Improper Batch Design • Check Batch design, Admixture

Over Designed for length (accompanied with excessive camber)

• Verify Engineering

Curing Methods • Water

• Steam

• Natural

• Insulation, Plastic Covering, Burlap

Curing methods will vary by location and must take into consideration ambient

conditions and humidity. The purpose of controlled curing is to reduce/eliminate

shrinkage cracks. There are specific curing instructions for each method in the

QC section of the Manufacturing Handbook.




Longitudinal Cracking Longitudinal cracking refers to cracks along the length of the piece. It can be visible either in the top, inside the core wall or along the sides.


Improper Detensioning Procedure • Check Procedure, Adjust as Required

Worn or damaged core • Inspect/Replace

Improper Storage and/or Handling • Adjust Procedure

Bad Batching resulting in delamination

• Check Batch design, Adjust as Required

Cables not aligned properly, too close to core wall.

• Check Cable layout compared to machine set-up, adjust as necessary

Variations in Stressing Tensions • Check Procedure, Adjust as Required

No transverse re-bar rods used (8’) • Use transverse rods or scrap cable at

ends/middle

Improper strand slipping procedure • Verify Engineering




Lines, Cracks on Sides of Product


Sideforms Improperly Adjusted • Check front width and pitch settings,

readjust as necessary

Incorrect Batching • Adjust water and/or plasticizer in batch

design

Sideform Wear Plate edge too

sharp • Contour as necessary

Sideform Not Smooth • Sideform Wear surface should be free of

rust, burrs, paint and graphite residue.

Over Compaction, Drag • Reduce amount of material, check water

amount.

Over working the product • Increase production speed

Vertical pitch is built into Sideforms. It is not necessary to adjust the pitch of

Sideform Carriers other than to make sure that they are vertical level. Minor

width adjustments can be made to Sideform Adjusting Nuts while producing or

during setup.

Care must be taken to not overly adjust the width while running, as this will cause

Sideforms to bind, and likely contribute to the lines on the sides of the product.

Over adjustment can sometimes lead to cave-ins on the sides as well.




HORIZONTAL CRACKING (END SHEAR)

The primary reason for Horizontal Shear is excessive Strand force in the ends of an

individual slab (plank).

We have tested and proven in production that by limiting the Strand force to the

equivalent of six (6) 1/2” (12,7mm) Strand at the end of a plank, you can eliminate

the excessive force that causes the Horizontal Shear.

On our Strand Slip Chart we show the number of Strand to slip to minimize End

Shear and the number of Strand to be slipped to convert a higher series (more

Strand) slab to a lower series slab.




The back side of this chart explains how to read the product series and how to use

the chart:

Product Being Produced > 301212 301210 301208 Strands to be slipped to

Control End Shear > >

(6) .6m ea. end (4) .6m ea. end (2) .6m ea. end

Example: On a 30cm product when 12 Strands are used, should be slipped .6m

from each end. Several methods can be used to slip Strand, however the most

consistent is the use of a paintable retarder directly on the Strand to be slipped.




Photo shows production worker applying Retarder on Strands.

Locations that are to be slipped are marked on the Casting Beds by the Layout

Personnel (red crayon marks) approximately 0.6m from the end of the Slab

(marked on edge of Casting Bed). These locations should be checked by Quality

Control prior to the workers applying the Retarder. Care must be taken to prevent

Retarder from being applied to the Casting Surface. A less experienced worker

would use a piece of wood or cardboard under the Strand to prevent contamination

of the Casting Bed.

The same method of painting the Strand with Retarder is used for converting high

series slabs.




Bottom Web Variation The recommended bottom web dimensions are shown on the Cross Section

drawings for each depth of product. Specifications for each product are located

in the Manufacturers handbook. This measurement is considered the optimum

thickness to allow the hollow core slab/panel to perform structurally.

Measuring Bottom Thickness

• On any series of Cores the bottom web thickness is measured by placing a

string line or straight edge across the bottom rear of the Sideforms.

• Measure from the string/straight edge to the bottom rear of the Core

• Each Core should be measured at this time to insure proper set-up of the

Core Assembly for production.

Measuring bottom web dimensions




Adjusting Bottom Thickness

If it becomes necessary to adjust the bottom thickness, it is recommended that

the Trowels be moved for minor adjustments rather than the Oscillator. If

frequent adjustment or the adjustment distance is considerable, a shim can be

used between the Core Assembly Master Plate and the bottom of the Oscillator

plate.

It is desirable to avoid having to adjust for different Core Assemblies in order to

facilitate changeover speed and maintain product accuracy. Refer to the cross

section dimensions and shim according to manufacturer’s specs. If help is

needed to determine shim sizing, contact Spancrete Machinery.

If an Oscillator adjustment is necessary, the Connecting Rods may have to be

adjusted to maintain even force and spacing. This is referred to as “timing” the

oscillator.

**Correct bottom web thickness is more important than top web thickness. Older manuals may refer to measuring from the bottom of the finish Trowelers to the top of the Cores in the setup section. This may be used as a rough guideline, but should not be used as the final set-point.




Side Tearing and Pulling Tearing on the side is often caused by a Sideform problem, but can sometimes

be caused from a bad batch, as seen below. You may notice that the tearing

occurs on one side only, or more on one side versus the other. This is an

indication that there may simply be a Sideform issue.

• Be sure that Sideform Carrier Brackets are level and that Sideform is able to

move with little restriction. Remove the Oscillator pin if necessary to

determine an even pull.

• Check the Sideform width in the front of the machine vs. the back. There

should be no more than 1/4" (6mm) difference.

• Check to see if Sideform is rubbing on Troweler Plate, adjust Sideform as

necessary.




• Check Sideform drive pins on Oscillator. Make sure they are not loose. This

can cause erratic movement leading to tearing.

• Check timing of the Oscillator, adjust as necessary.

• Check the condition of the bushings and pins on the sliding blocks. Ensure

that adequate grease is in the bushings and pins, and that they are free of

grit.

• Riding too close to Casting Bed can cause tearing also.

• Verify Oscillator Speed is set correctly. If a batch is not flowing well, it will

cause drag and tearing. Turn up the speed until batch problems can be

solved

Tearing on Bottom Edge of Product:

• Misaligned Rear Adjustable Bevel Strip - Rear Adjustable Bevel Strip may

be set at an improper angle. Adjust or replace as necessary

• Worn Front Bevel Strip - Over time, the Front Bevel Strip can become

dished out, causing an excess of material for the Rear Adjustable Bevel

Strip to finish. Replace as necessary.




Web Tearing If outer web tearing is an issue, go through the Sideform check list as described

above. For interior web tearing, check the following.

• Misaligned Cores – If Cores are not properly set-up and adjusted they can

contribute to a web tearing issue.

• Check batch design. Many times, web tearing and excessive porosity is

related to incorrect batching. Material must flow through Slipformer easily to

allow the concrete to be evenly dispersed. This will allow for better

compaction. At the same time, there must be enough moisture content to

activate the cement.

• Check admixture - Although this is also batch design related, make sure that

the admixture used in the correct volume and is dispersed throughout the

mix.

• Tearing can also be simply a case of too much or too little water, so

experiment with water content prior to making any changes in machine set-

up.




In the example in figure 8 above, de-lamination is evident.

The middle portion of the plank was not receiving adequate feed and un-

compacted material from the rear hopper was forced to fill the void. This

condition also resulted in considerable amounts of porosity in the webs as well as

de-bonding of the Top Strands. Because the material was not flowing through

the machine correctly, an adjustment was made to the aggregates and a different

admixture was used to allow for a higher moisture content in which to fully

activate the cement.

De-lamination




Figure 1

Figure 9, is classic “tearing” which in this case, was related to admixture. The mix

was initially to dry, but increasing the moisture content to the proper cement to

water ratio produced a very sticky mix which led to over-compaction. The

admixture was not allowing us to increase the moisture content to acceptable

levels to activate the cement. The addition of water created excessive drag and

sticking. Changing the admixture allowed us to increase the water content,

reducing drag and over-compaction.

Tearing




Batch Plant Recommendations

• Be sure that your batching system has a feature which will enable mixer

operator to add or subtract water if necessary without making an

adjustment to the sand, cement, or coarse aggregates.

• Use Moisture probes to adjust for changes in moisture content in

aggregates. Daily extremes in humidity and rainfall will directly affect the

amount of moisture in the material.

• A means to regulate the temperature of the mix. A batch is considered

optimum around 65o-70o F (18o – 20o C) degrees.

• Have direct communication with the machine top operator. Radios are

essential equipment to allow the operator to keep track of mixes.

• Keep mixer clean. Allowing hardened chunks to build-up and fall into the

batch could catch beneath the cores and wedge in the rear hopper.




NOTES:

INSTRUCCIONES GENERALES DE OPERACIÓNINSTRUCCIONES GENERALES DE OPERACIÓN Fabricantes Manual D-3...

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