Frequently Asked Questions:

1. What are your hours of operation?
2. How can I pay for my concrete?
3. How do I find a good contractor?
4. How do I place an order?
5. What information will I need to place an order?
6. How much notice is required when placing an order?
7. What if I need to change or cancel my order?
8. How do I ensure my concrete will last?
9. What is fiber reinforcement?
10. Why can’t the concrete be sandier or wetter so it’s easier to pour?
11. What reasons should cause a pour to be cancelled?
12. How do I prepare for my pour?
13. How do I 1determine how much concrete I will need?
14. What are control joints and how many do I need?
15. How much does concrete color cost?
16. How can I ensure my colored concrete is consistent in color?
17. What are your delivery fees?
18. Is there a minimum amount that I have to order?
19. What do I do with my leftover concrete?
20. What area do you deliver to?
21. Are there any additional fees?
22. What is meant by curing concrete and how do I do it?
23. Why should I cure my concrete?
24. What method of cure should I use for my job?
25. What should I do to the concrete after it’s been poured?
26. What type of sealer is available?
27. How do I apply my sealer?
28. Will my sealed concrete be slick?
29. How long before I can drive on my concrete?
30. What caused these blemishes on top of my slab?
31. What makes good quality concrete?

1. What are your hours of operation?

A. Our dispatch is generally available from 5:00 am to 5:00 pm Monday through Friday and from 6:00 am to 12:00 pm on Saturdays.  If all orders are dispatched early on Saturday, dispatch may close early.  Our office is open Monday through Friday from 8:00 am to 5:00 pm.

2. How can I pay for my concrete?

A. You can pay several different ways. 

1) First is with cash on the jobsite (drivers do not carry change)

2) You may pay with a credit card.  We prefer to have the cardholder come into the facility so we can verify that it is not a stolen card, but payment may also be made via the telephone or website.

3) If your contractor is an account holder, they may pay for the concrete directly.  This can cause a problem if the contractor is not reputable and does not actually have an account established.  As a material supplier, we are entitled to mechanics lien rights.  What this means is when we supply a product, if we are not paid for it, we have the right to file a lien on the property where the material was supplied.  The best way to ensure this does not happen is to check the Contractors State License Board (CSLB) website for the contractor’s license status.  Next, check with us to verify account status of contractor.  Finally, either pay for the concrete yourself or issue a joint check made out to the contractor and Allied Concrete & Supply.

3. How do I find a good contractor?

A. There are several things to do.  Check with our dispatcher or sales staff to see if they know a contractor or ask friends and family if they know of someone.  You can also look in the telephone book or check around your neighborhood.  Once you have a list of a few contractors, check the CSLB website for each contractor’s license and bond status.  Next, get references from the contractors for work that they’ve done previously.  Call the provided references!  If possible, go look at some of the work that they’ve done.  Keep in mind, price is not the only factor to consider when looking for a contractor.  In most cases, you get what you pay for.  If one price is extremely low, they are probably not figuring something that’s necessary into their bid.

4. How do I place an order?

A. Call our dispatcher at (209) 524-3177 ext. 2.  Make sure you have all your information that we will need ready.

5. What information will I need to place an order?

A-            1) Know when you want to pour (the date and time preferred), our dispatcher will let you know what the availability is for that date and time. 

                  2) Have your dimensions ready or know how many cubic yards of concrete you need and what type of mix you will need (5 sack ¾” rock, 6 sack Pea Gravel, pump mix, etc.).  If unsure of requirement, ask our dispatcher for a recommendation.  PLEASE REMEMBER, it is your responsibility to know what local codes and restrictions are, not our dispatcher’s, but most commonly, a 5 sack ¾” rock mix (3000 psi) is used for driveways, sidewalks and patios.  A 6 sack pea gravel mix (2000 psi) is used primarily for pumping concrete.  For heavy vehicle traffic, a 6 sack ¾” rock mix (4000 psi) may be the right choice.

                  3) Know the “slump”, or how fluid you want the concrete.  This is a physical measurement that usually tells how much water is desired in the mix, or if a high strength/low permeability or colored mix is used, concrete admixtures can increase slump without damaging concrete or color like water will.  Usually a 4” – 5” slump is recommended. (for more information, see section on too much mix water and sand).

                  4) Know the address and cross streets for delivery.

                  5) Have a contact telephone number for the owner and contractor.

                  6) Let us know if you’re planning on pumping the concrete, need to schedule our concrete pump with your order, and if you need any extra products such as fiber, accelerator, retarder, color, etc.

                  7) For colored concrete, know which color you want and who the manufacturer is.

6. How much notice is required when placing an order?

A. This will vary depending upon the size of the pour and the desired day and time of delivery.  Generally, we require a couple of days notice for weekdays and approximately 1 weeks notice for Saturday deliveries.

7. What if I need to change or cancel my order?

A. Call our dispatcher as soon as possible.  Depending upon the delivery address, we will need approximately 1-2 hours notice minimum on the day of delivery.  IF LOAD HAS BEEN DISPATCHED ALREADY, YOU WILL BE BILLED FOR THAT LOAD AS CONCRETE IS A PERISHABLE ITEM. 

8. How do I ensure my concrete will last?

A. There are several things needed to make sure your concrete is as durable as possible:

1) The use of high quality materials such as cement, aggregate and clean water

2) Proper delivery of product

3) Proper placement, including grade preparation

4) Proper curing and sealing methods

5) Proper reinforcement, such as rebar or fiber reinforcement

9. What is fiber reinforcement?

A. Fiber reinforcement is an economical and easy to use alternative to wire mesh reinforcement.  It is extremely effective as it gets dispersed throughout the concrete load during transit to the jobsite.  Unlike wire mesh that gets pushed to the bottom of the slab during the pour from workers walking on top of it, fiber will stay suspended within the slab.  The fiber decreases the chances of plastic shrinkage cracking (a type of cracking common in concrete that isn’t cured properly or has been subjected to harsh environmental conditions the same day it is poured) and essentially, helps to keep small, microscopic cracks from becoming large cracks.  It is commonly used in conjunction with wire mesh as well.  Fiber reinforcement is not usually an alternative for rebar. 

Fiber comes in two different types.  The first, commonly called “Regular fiber”, is a fibrillated polypropylene (plastic) fiber and is easily seen in the concrete as well as during the finishing process.  Usually, after poured, it will stick up out of the top of the slab.  The other style, commonly referred to as “Stealth”, lives up to its name as it is extremely difficult to see in the concrete.  It is usually made up of fiberglass fibers (large enough so inhalation is not a concern), cellulose based or a monofilament polypropylene (plastic).  This fiber is ideal for decorative or architectural concrete.  It will not affect the color of concrete and does not affect the finish like “Regular fiber” does.  I would not recommend anyone pour residential or commercial concrete without the use of fiber reinforcement.

10. Why can’t the concrete be sandier or wetter so it’s easier to pour?

A. If too much sand or water is added to make the mix easier to use, the overall quality of the mix will be sacrificed.  Wet, sandy concrete is easy to screed, but is weaker and more susceptible to cracking and surface blemishes such as efflorescence (unsightly white salt deposit).  If too much water is used, the concrete will also be more porous as well as weaker.  The more sand you put in the mix, the more water you need to make it workable, so it becomes almost a self feeding problem.

11. What reasons should cause a pour to be cancelled?

A., This will depend on the experience level of the finishers.  The most detrimental environmental conditions are wind, dry/arid conditions, very hot weather, rain and freezing conditions. 

                  1) Wind- Windy conditions will cause plastic shrinkage cracking to occur on the surface of the slab.  This can be partially controlled with the use of fiber and a good curing method, but it is extremely advisable to postpone even if experienced finishing crew.

                  2) Dry/arid conditions- This is similar to wind in that it will cause plastic shrinkage cracking to occur.  It can be combated with Con-film and concrete retarders as well as with proper curing methods.

                  3) Very hot- This can be combated with the use of our concrete retarder.  You need to know how long you would like to have the concrete retarded for though (usually 1-1 ½ hours).

                  4) Rain- Depending on the amount of rain and placement of the concrete it may or may not be a requirement to cancel.  The concrete can be covered with plastic (visqueen) if it begins to rain after finishing in a lot of instances.  If the concrete has runoff water, such as from a down spout, going across it, you will lose the top layer.  If puddles are present prior to pouring, it may result in blotchiness or efflorescence (white powdery substance on surface of slab) occurring at a later date.  Another concern is access to and from the site in rain.  If the truck becomes stuck, it is the property owner’s responsibility to pay for any damages to the truck and to pay the tow bill too.  It is usually not a good idea to pour if rain is predicted in the immediate future.

                  5) Freezing Conditions- Do not pour if sustained freezing conditions are predicted.  It doesn’t usually happen here, but if you get caught, cover the slab with straw, heavy plastic or blankets.  If the top freezes on your concrete, the top will become “delaminated” or peel off.  If there is a low predicted during the night of 30 degrees F, you are probably ok, but if a hard freeze is coming, wait to pour until it passes.

12. How do I prepare for my pour?

A-            1) If hiring a contractor, make sure they are licensed and their license status is in good standing by visiting www.cslb.ca.gov and select “Check a license or HIS registration” on the left hand toolbar.  Ask the contractor for recommendations of previous clients and make sure that you go see jobs they’ve recently completed.  Check with our dispatcher or sales staff if they’ve heard of the contractor or know anything about them.

                  2) Find, clearly mark and notify all involved parties of jobsite hazards such as septic tanks, low hanging wires or tree limbs or other obstacles.  THIS IS EXTREMELY IMPRORTANT!!!  Make sure all tree limbs are trimmed back and there is adequate access to and from the site.  Please remember, as soon as our truck leaves the paved road, the property owner will be responsible for all damage that occurs to the truck or property (this includes tow bills if truck gets stuck).

                  3) You need to have an adequate area for clean-up.  If not available, inform or dispatcher at the time of placing order for the necessity of a reclaim bucket on the truck.  All fines for dumping in gutter or if runoff runs into the street will be paid by the owner.  Please note that these can be extremely expensive depending upon your location.

                  4) Ensure your forms are sound and your grade is even.  If your grade is off, even by ¼”, it can result in a large difference in product required over the total square footage of the pour. 

                  5) Make sure the contractor has accounted for proper drainage of water off the finished slab.  There should be between 1/8” to ¼” inch of fall per foot to get proper drainage.

6) Ensure sure your grade is well compacted and damp.  There should not be any standing water though. 

13. How do I determine how much concrete I will need?

A. You can use the concrete calculator or call us with your dimensions to get a rough estimate.  Keep in mind, not seeing & having measured, we will not guarantee volume required for your job.  A small variance in measurement can make a large impact on overall requirement.  For rough estimates, you can figure 1 cubic yard of concrete will cover approximately 80 square feet when using a 2” x 4” form.

14. What are control joints and how many do I need?

A. 1) One of the only guarantees with concrete is that it will crack.  Control joints must normally be used to allow the concrete to crack at predetermined intervals.  Although, if not placed close enough together or if not put deep enough into the slab, the concrete will seek its own location to crack.   Please keep in mind that even though control joints are placed properly and at the correct intervals, this will not ensure that the concrete will not ever crack outside of the joints as there are many other factors that play into concrete cracking.  This is the primary method of trying to minimize an undesirable outcome. 

2) Determining where control joints go is almost an art form, but there is a method behind it.  To determine the limits you’re trying to work with, you should multiply the depth of the slab (in feet) by a minimum of 24 and a maximum width of 36.  The maximum distance between joints should be 15 feet.  The length shouldn’t be any more than 1.5 times the width.

Example 1- You have a sidewalk that is 40’ long x 3’ wide and 4” thick.  You convert your depth into feet (divide 4” by 12” = .333).  Multiply this by 24 to 36 (.333 x 24 = 8’ or .333 x 36 = 12’).  The rule is no more than 1 ½ times your width though (1.5 x 3’ = 4.5’), so your spacing should be every 4.5’ you should have a joint.

Example 2- You have a patio that is 8’ wide by 25’ long and 4” thick.  You convert your depth into feet (divide 4” by 12” = .333).  Multiply this by 24 to 36 (.333 x 24 = 8’ or .333 x 36 = 12’).  Your width would fit nicely between the 8’ – 12’ rule for the 4” thick concrete.  This being the case, 1.5 times the width is 12 feet.  This is right at the maximum, so it may be advisable to joint it down the middle of the slab, but you should be ok at 12’ as well.

If putting concrete up against a pre-existing structure, a piece of expansion felt should be used as well.  This should be a minimum of ¼” thick and is usually ½”.

15. How much does concrete color cost?

A. This varies greatly depending upon the cement content of the mix and the color choice.  The price range is from approximately $6.25 up to $131.00 per cubic yard for a 6 sack mix for the color only.  The darker the color, the more expensive it is.  Some of the more popular choices are about $50.00 per cubic yard for a 6 sack mix.  Ask our dispatcher or a salesman for a quote on your job.

16. How can I ensure my colored concrete is consistent in color?

A. 1) You need to know approximately how many cubic yards of colored concrete you will need.  If pouring multiple colors, you should know how much of each color is needed.  If you need more than 1 load, you should order your loads as close to the same size as possible.

                  Example 1- If your job requires 21 cubic yards of concrete, you should order two 7 yard loads and a clean up (the exact amount required to finish pouring the last 1/3) which should be 7 – 8 cubic yards depending upon your grade.  This will help by making everything as consistant as possible, as opposed to ordering two 9 ½ yard loads and a 2 – 3 yard clean up which could come out to wet or dry because it is harder to control the consistency on smaller loads.

                  If you are pouring over multiple days, you should try to keep the days as close together (so you don’t have changing environmental conditions) and keep the pours approximately the same size so everyone knows what to expect. 

                  Example 2- If you have 50 cubic yards to pour, but only feel comfortable pouring 15 cubic yards at a time maximum, break your pour into four separate pours of approximately 12 ½ cubic yards each.  It doesn’t have to be exact, but you should try to keep it close.  In other words, if it’s more convenient to pour 10 yards one day as you reach a natural breaking point, and 15 yards on another day, that would be ok too.

                  2) Make sure your sub-grade is prepared properly.  You should have a consistent depth across the slab and your sub-grade should be moist, but NOT overly wet.  If you pour over the top of puddles or mud puddles, it will contribute to blotchiness in the slab color and increase the risk of efflorescence. 

                  3) Make sure all the loads are poured at the same slump (see information needed to place an order).  If water needs to be added, do so at the very beginning of the load and make sure that it gets mixed in thoroughly (should be 70 revolutions of the trucks drum at high mixing speed and should take about 3-5 minutes- all trucks have a drum counter, just make sure to tell the driver you want 70 revolutions of the drum).  If not mixed sufficiently or if more water is added later in the pour, the part of the load that has more water than the rest will be more diluted, thus having a lighter color that the rest of the pour.

                  4) Consider environmental effects, especially if pouring on multiple days.  Colored concrete tends to set up a little bit faster than plain concrete.  If it’s warm outside, you should consider using Delvo concrete retarder (slows down the chemical reaction for concrete by a specified amount).  Typically, 1 – 2 hours retardation is a good idea with color, depending upon how far away the jobsite is from the plant, the environmental conditions and the experience level of the finishers.  If nothing else, you should retard the concrete for the trip to your jobsite.  This will buy you a little extra time in case you need it (better to have and not need than to need and not have, as the concrete won’t wait!) and will help prevent the need to add additional unwanted water.

                  5) DO NOT spray the surface of the wet concrete with water.  This will only lighten the color of the surface.  If additional time is needed to finish working the concrete, use Con Film surface retarder.  If broom finished, be careful not to wet the broom to much as this too will cause the surface color to be diluted, resulting in light to dark streaks as the broom goes from wet to dry.

17. What are your delivery fees?

A. We have a $50.00 short load fee for orders less than 6 cubic yards.  There is a $20.00 fuel surcharge for each load that goes out as well.  These are subject to change at any moment, please call to confirm current price.

18. Is there a minimum amount that I have to order?

A. Yes.  For regular concrete there is a 2 cubic yard minimum.  For colored concrete, there is a 3 yard minimum requirement for batching purposes.  This is to help ensure as consistent a mix as possible.  Even if you are ordering a clean up, you should not order less than 3 cubic yards of colored concrete.  For aggregate deliveries (rock and sand) there is a 10 cubic yard minimum.

19. What do I do with my leftover concrete?

A. If you have concrete left over after you are finished pouring, you can send it back on the truck to our yard and we will dispose of it without any additional charges.  If you would like the driver to take it to another location that you want to pour it at, you may be subject to a delivery charge.  In addition, you need to let the dispatcher know prior to pouring that you want to do this for scheduling purposes.

20. What area do you deliver to?

A. Stanislaus county, southern San Joaquin county and northern Merced county.  We also service the La Grange & Don Pedro area.  Some areas, such as La Grange/Don Pedro, will require an additional delivery charge, called a zone delivery.  Please ask when placing an order if there are any additional charges for delivering to your area.

21. Are there any additional fees?

A. If you do not have a place to rinse the truck down ON YOUR property, there is a $2.00 environmental fee for using our reclaim system on our truck.  Be sure to alert dispatcher prior to delivery so proper equipment can be dispatched for this.

22. What is meant by curing concrete and how do I do it?

A. Curing concrete is essentially keeping the moisture from evaporating out of the concrete prematurely.  This is begun immediately following the completion of the finishing process, the same day the concrete is poured. This can be done by several different methods, although not every method is ok to use for every job.

1)    Moist curing is where most people get the idea that they should spray their freshly poured slab with water.  The correct way to moist cure is by flooding the slab and maintaining the water on it for approximately 1 week or by the use of sprinklers, which must run continuously for about the same amount of time, not allowing the surface of the concrete to dry at any location for the duration of the cure process.  If the top of the concrete is sprayed and let to dry and repeatedly, more harm than good may be done as this contributes to possible cracking from the expansion & contraction of the slab, among other reasons. 

2)    Another method is by covering the concrete with a “blanket”.  This is both figurative and literal as there are special blankets that can be used that will trap the moisture in the slab and help keep the slab from freezing in cold climates.  You can also use visqueen with a minimum thickness of 4 mil (white or clear in color so as to reflect sunlight) to prevent the moisture from evaporating, but the edges must be covered and secured.  Most commonly used is a liquid cure compound though.  This is sprayed on the top of the slab in even coats and acts as a figurative “blanket”, trapping the moisture in.  For decorative concrete, this is the most advisable method.  See later section on which cure is right for you for explanation.                 

3)    The last method is a combination of the previous two methods, where you can use wet burlap or wet straw piled 6” thick to cure the concrete.  Similar to the flooding method, extreme caution must be used to not allow these products to dry out for the duration of the curing process.  If they do dry out, they could have the exact opposite of the desired affect by actually pulling the moisture out of the slab prematurely.

23. Why should I cure my concrete?

A. There are several reasons why, but most importantly is because you will help to create as durable and long lasting a product as possible.  By not curing your concrete, you are more likely to experience a myriad of different types of unwanted cracking, efflorescence and other surface blemishes.

24. What method of cure should I use for my job?

A. Not every method of cure is advisable, especially when colored concrete is concerned.  If pouring colored concrete, you shouldn’t cover the slab with a blanket, burlap, plastic or straw as it will discolor the surface and you will see where each item was resting on the surface of the slab.  In addition, moist curing is not advisable as it will lead to blotching.  If the slab is stamped, water can not be used as the release agent will repel the water.  If an antique release (colored powder) is used in the stamping process, this will usually suffice as an adequate cure under normal conditions.  For broom finished or hard troweled colored concrete, a liquid cure agent, such as Cureseal-w, should be used.  The actual cure used will depend upon the desired sealer as some cures are not compatible with some sealers.  Let our dispatcher or salesman know if you would like a “wet look” gloss sealer or a semi-gloss look.  If pouring plain, uncolored concrete, any method used should be ok depending upon jobsite conditions and which, if any, sealer is wanted.

25. What should I do to the concrete after it’s been poured?

A. 1) If it’s decorative concrete with color, stain or stamp work, the concrete will need to be sealed afterwards.  This sealer will need to be maintained on a regular basis.  The regularity of maintenance will depend upon the amount of traffic on it and the type of sealer used as well as other environmental conditions.  If stamped or stained, you will need to clean the concrete prior to sealing it.  Ask our salesmen or dispatcher for recommendations on which sealer to use.  Your concrete contractor should be able to clean the slabs and apply the sealer for you. 

2) If it is broom finished colored concrete, you will want to make sure you apply a cure compound (see above section on curing).  Ask our sales staff which is right for you.  The cure compound should be applied after the finishing process is complete, before the contractor goes home the day of the pour. 

26. What type of sealer is available?

A. There are two primary types of sealers.  The first is water based and the second is lacquer based. 

                  1) Our water based sealers can be broken into 3 basic subcategories, good, better and best.  They are all semi-gloss and range in durability from average to superior.  The “good”, called Cementone, is very affordable, but requires more maintenance than the others.  It typically needs to be resealed at least once a year.  The “better”, called Cureseal-w, is also very affordable, but the real benefit is that this can also be used as a cure compound for your slab.  This allows you to begin protecting your concrete from harmful UV rays, staining and other damage immediately after pouring!  Finally, the “best”, called Selectseal-w, has the far superior durability of any of the water based sealers and also superior UV resistance, typically requiring to be resealed every couple to three years depending upon wear patterns and environmental conditions.  The trade off is this is an expensive sealer. 

                  2) Our lacquer based sealer, called Premium Gloss Sealer, is obviously a gloss sealer, but can be altered into a flat finish with treatment by a flattening agent.  This is an extremely durable product that is reasonably priced, but you must wait 20 – 30 days prior to application.  This is because the water present in the slab from the curing time must be allowed to escape.

27. How do I apply my sealer?

A. There are a couple different ways to apply sealer.  Application is essentially the same for either the water based or the lacquer based products.  You can apply with an airless sprayer, roll the product on with a low nap roller or squeegee it on.  There are a couple critical issues when applying sealer though.  You must not apply when there is any moisture on the slab or if there is excessive moisture in the air.  Also, you must not apply the sealer when the concrete slab temperature is above 80 degrees Fahrenheit.  This can be confusing as air temperature may be significantly different from the slab temperature.  You should also wait to apply if overly windy conditions exist.  You typically need to apply two coats of sealer to seal your concrete effectively.  It is important you wait a minimum of 4 hours between applications so the gases from the slab and sealer can be allowed to escape prior to the next coat being applied.  If applied to early, these gases will become trapped in the sealer.  Caution should also be used not to apply the sealer to heavy on individual coats for the same reason.  The manufacturer’s recommendation for application is to apply the water based with the use of an airless sprayer and to roll the lacquer based on with a low nap roller. 

28. Will my sealed concrete be slick?

A. Application of sealer to your concrete will cause it to become slicker than when not applied, but we have a product called “Safety Track” which can be applied with your sealer, when your applying your sealer, to help reduce this affect.  This is especially effective for pool decks, where water is continually splashed up on the surface.

29. How long before I can drive on my concrete?

A. This depends on what you’re driving (how heavy it is), the type of concrete used (sack content and mix design) and how the concrete was placed (if proper placement methods were followed or the mix was altered).  Most generally, it will be ok to drive on after about one week.

30. What caused these blemishes on top of my slab?

A. Check our colored concrete troubleshooting guide in the color section of our products page or contact our salesmen.

31. What makes good quality concrete?
A. There are several basic requirements for good quality concrete:

* Good materials-cement, aggregate admixtures and water
* Proper proportioning of these materials
* Thorough mixing
* Skillful placing and finishing
* Proper curing

All of these requirements are important, and failure to satisfy any one of them will often result in a reduction in quality. The materials used by Allied Concrete. meet quality requirements. The specifications relate to important properties such as amounts of nondurable substances permitted in aggregates and how fast the cement will set and gain strength. Multiple tests are conducted to verify that, the materials we use meet and exceed applicable specifications.

Another key to having excellent concrete is proportioning. Proportioning is simply deciding how much of each ingredient will be put in the concrete. A temptation to use too much water generally results from an effort to make placing operations easier for the contractor. Overly wet concrete flows into the forms more readily, is easier to compact and to strike off.

Everything about overly wet concrete is easier-except the maintenance problems that will begin to appear on a surface that could just as easily have been trouble-free for many years.

32. Why is too much mixing water dangerous?
A. Simply because excessive water makes a more dilute cement paste. Not all of the water in any concrete reacts with cement and when there is an excessive amount of water it leaves small voids in the hardened paste. This makes the concrete weaker, more porous and less durable.

33. What are typical concrete requirements for around-the-house patios, walks, driveways?
A. The contractor should provide the ready mix producer with the following basic information:

* Maximum size of coarse aggregate.

* Slump of the concrete. Slump is a measure of how readily a concrete flows. Slump values are determined by test. Increasing the water content increases slump, and a slump that is too high indicates that too much water may have been added to the concrete. A 4 to 5-inch slump will give a good, workable mix. A stiffer mix (lower slump) will usually be more difficult to place and a wetter, soupy mix won't be as strong and durable.

* Strength required. In severe climates where concrete will be exposed to freezing and thawing, a compresive strength of about 4000 pounds per square inch (psi) is a common specification. Strength is measured on standard test cylinders cured under standard conditions. A strength of 3000 to 3500 psi at 28 days is adequate for nearly all concrete not exposed to numerous freezing and thawing cycles or to deicing salts.

34. What steps can be taken during construction to ensure good performance?
A. The homeowner will want to be sure that, for flatwork, the underlying soil (subgrade) is well compacted by the contractor and not extremely wet or muddy when concrete is placed. Workers should also check the elevation of the subgrade by measuring down from a straightedge laid on the forms.

High spots should be removed; otherwise the slab will be too thin in spots. Low spots should be filled in and compacted; otherwise the buyer may pay for more concrete than is needed. Flatwork for driveways, sidewalks and patios is typically 3 1/2 to 4 inches thick.
Side forms should be set so that the finished concrete surface is sloped slightly for drainage. A slope of 1/4 inch per foot of width is recommended for driveway slabs.

Joints are needed in most concrete slabs. They control cracking by dividing the slab into square sections for driveways and patios, the joints should usually be spaced 10 feet apart or less. For sidewalks they are typically spaced only 4 or 5 feet apart. Joints must be cut to a depth of at least one inch. If the joints aren't cut deep enough or if no joints are provided, the slab will probably crack at random locations.

Proper joint spacing is determined by multiplying the depth of the pour (in feet) by a minimum of 24 and a maximum of 36. The Maximum distance between joints is 15 feet apart. Your length should be no more than 1.5 times your width.

Where flatwork abuts another structure, it should be separated from the structure by an expansion joint. Usually a premolded strip of compressible material is inserted at locations such as the intersection of a driveway and garage slab or a patio and the foundation wall of a house.

35. What is meant by curing?
A. A chemical reaction between cement and water makes concrete strong and durable. The purpose of curing is to make sure that little or no water is lost from the concrete during the early stages of this chemical reaction.

36. How is curing accomplished?
A. The newly placed concrete should be covered or sprayed with a material that will retain the moisture within the mix. Membrane curing compounds sprayed on the surface are the materials most commonly used. They are very convenient but they must be applied immediately after the concrete is given its final finish and care must be taken apply them thoroughly and uniformly. Coverings used to cure concrete include wet burlap, plastic sheets and Kraft paper. If burlap is used it must be kept continuously wet. The curing process should be continued for at least 72 hours and twice as long if the temperature is below 50 degrees F.

It is up to the contractor to cover the concrete and start the curing process. But it is usually up to the homeowner to follow through from there and make sure that curing proceeds uninterrupted for the required time period.

37. How do you find a good contractor?
A. First of all, don't pick him entirely on the basis of cost. In concrete work, as in any business, you get what you pay for. Cost should be a consideration, but it should not be the only consideration. Knowledge, competence, integrity and experience are the qualities to seek in a contractor. To obtain the names of qualified contractors, talk to the dispatchers or friends and family. Then take a look at a few of the contractors' completed jobs, particularly some that were done several years ago. If you like what you see, you can feel easier about seeking bids from them, knowing that they do good quality work.

38. What performance should you expect from concrete placed around your home?
A. Good quality concrete-properly proportioned, mixed, placed, finished and cured-will give maintenance-free service for many years. Concrete work, properly done, will usually last much longer than the need for which it was originally installed.

39. How do I know how much concrete to order?
A. When you have measured the length and distance of the area you are interested in pouring, call our dispatch center and they will provide an exact measurement for your project.

40. What kind of reinforcement should I use in my concrete?
A. Much of that depends on what the concrete is being used for. In most cases, Fibermesh is an excellent no-hassle solution to providing additional strength. We also suggest using rebar or wire depending on the use.

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