Question 1

What is ready mixed concrete?

Accepted Answer

Ready-mixed concrete is a combination of Portland cement, rock, sand, and water. Also, concrete may contain some admixtures including mineral and chemical. These admixtures improve the properties of concrete.

Question 2

How far apart should I place my contraction joints?

Accepted Answer

Spragues’ Ready mix recommends that you place your contraction joints no more than 2 times in feet the thickness in inches of the slab. (4” slab 8’ joint spacing) These joints must be a minimum of ¼ the depth of the slab. (1” on 4” slab) Also, it is recommended that you attempt to design panels that are as square as possible. (Avoid exceeding 1.25 times square)

Question 3

How should I cure my concrete?

Accepted Answer

Spragues’ Ready Mix recommends that you cure your concrete with a liquid membrane curing compound. The curing process should begin immediately after final finishing. (Colored concrete may require curing compound that is approved for application)

Question 4

How should I prepare my sub-grade?

Accepted Answer

The sub-grade should be well compacted, uniform in depth, and well draining. Also, a fill of granular nature such as sand, rock or crushed base and dampen this base before placing concrete.

Question 5

Should I use fibers in my concrete?

Accepted Answer

Spragues’ Ready Mix recommends the use of fibers for reducing the possibility of plastic shrinkage cracks. Fibers are used only as secondary reinforcement.

Question 6

How can I avoid concrete cracks?

Accepted Answer

There are many different types of concrete cracks. Proper joint layout is critical in flatwork. Pouring concrete with a low-slump is also very important. Cracks can also be caused from external restraint. (Pouring a footing and slab concurrently) Cracks can occur in between two immovable obstructions. If felt or foam is not used between a house and a block wall it is likely that a crack will develop. Crazing cracks (web cracking) often will develop when concrete is poured with a high slump and/or bleed water or water was introduced to the surface of the drying concrete before final set.

Question 7

How should I prepare for hot weather?

Accepted Answer

Concrete will set-up much quicker in hot weather. Ask our dispatchers to add a set retarder to your load. Make sure you have enough people on site to place the concrete quickly. It is recommended that the sub-grade is dampened before placement begins.

Question 8

How should I prepare for cold weather?

Accepted Answer

In Southern California our temperatures rarely drop below 40 degrees. Nevertheless, we recommend that when the mercury drops you use a set accelerator in your mixes. Also, pouring your concrete with a low slump will help increase your set times. When concrete is poured on a cold sub-grade set times also tend to be increased.

Question 9

What do I need to know about colored concrete?

Accepted Answer

Extra care must be taken when placing colored concrete. It is important that the slump remains consistent throughout each load. Also, as with any concrete, you never want to introduce water to the drying surface.

Question 10

How do I avoid discoloration of my slab?

Accepted Answer

It is important not to over use a steel trowel while finishing. This has an effect that “burns” the surface of the concrete and seals in moisture. (Trapped) Also, you do not want to introduce any steel onto the wet concrete until after all of the bleed water ahs disappeared. Avoid using calcium chloride for flatwork.

Question 11

How can I repair discoloration?

Accepted Answer

Discoloration is difficult to fix. However, the earlier you treat the surface the more effective it will be. Scrub white vinegar onto the dampened slab and hose off the surface before the vinegar dries. Vinegar is slightly acidic and will often open up the pores of the concrete and allow it to breath. Discoloration caused by calcium chloride will not be affected by this procedure.

Question 12

What Is Pervious Concrete?

Accepted Answer

Pervious concrete is concrete manufactured with zero fine aggregate. It allows water to pass through the concrete which eliminates storm water run-off. Pervious concrete pavement is a unique and effective means to address important environmental issues and support sustainable growth. By capturing stormwater and allowing it to seep into the ground, porous concrete is instrumental in recharging groundwater, reducing stormwater runoff, and meeting EPA stormwater regulations.

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