In a previous video, we explored the differences between granite and quartz countertops. Today
we’re going to discuss marble and concrete countertops. They aren’t as popular, but
they’re up there. I couldn’t find any samples of marble countertops, so I’m going
to use this mosaic marble Daltile from Home Depot as an example. I was able to find some
samples of prefinished concrete countertops from Dex Industries. In this video, we’re
going to compare how they are made, their physical properties, price, performance and
environmental impact.
Let’s start with marble countertops. Marble is a metamorphic rock made of the bones of
dinosaurs.
Shells, coral and fossils of marine organisms erode and settle to the bottom of the ocean
floor as sediment. Layers upon layers of sediment are pressed and cemented into limestone or
calcite or calcium carbonate. Limestone is recrystallized under the influence of heat,
pressure and chemical processes beneath the Earth’s surface to form marble.
Some forms of marble metamorphosed from dolomite, a type of limestone composed of calcium magnesium
carbonate. Pure marble is a bright white rock composed of an interlocking mosaic of carbonate
crystals. The presence of mineral impurities can cause it to change color and create characteristic
swirls and veins.
For example, iron and feldspar will turn marble pink. Iron oxides will cause yellow and brown
deposits. Serpentine will create a green hue. Porphyry will create violet coloring. Graphite
will turn marble dark and gleaming like gunmetal.
Marble is found in many places. Italy, Spain, Brazil, China, India, Portugal and Turkey
are among the world’s top producers of marble, with each co untry quarrying more than one
million tons each year. It is also quarried locally in Vermont, Texas, Indiana, Tennessee,
and Georgia.
Large blocks of marble are cut out of the earth and transported to a factory. They are
covered with a fiber mesh and glue to strengthen the block and make it safer for cutting. The
block is cut with a gangsaw machine into thinner slabs. Then they are polished with large industrial
sanders. Straight cuts are made with a wet saw. Irregular shapes and curves are cuit
with a water-jet. CNC machines carve out intricate edge profiles like an arc-shaped ogee edge
and a straight ogee edge. Thin edges can be laminated with epoxy for extra stability.
Finally the edges and the slab are polished manually to remove any scratches. These edges
can be round, bevel, waterfall or bullnose.
Since marble is 100% natural stone, every slab is different. Its patterns and veining
look soft and organic, unlike engineered quartz which can sometimes look fake. Marble has
been used to make sculptures since ancient times because it is relatively easy to chisel
and because of its sub surface scattering properties. Not all light reflects from a
surface. Some of it will penetrate below the surface where it is absorbed and scattered
internally. This property gives marble an attractive soft appearance that is good for
representing human skin.
Now let’s discuss how concrete countertops are made. The main ingredient of concrete
is Portland cement. Limestone, sand and clay are quarried and crushed into small rocks.
It is combined with iron ore and fly ash. The ingredients are the source of calcium,
silica, alumina and iron. They are ground, mixed and fed into a steel rotary kiln heated
to 2700F or 1500C. As the material moves through the kiln, certain elements are driven off
in the form of gasses. The remaining elements unite to form a new substance called clinker.
This is usually in the form of small gray-black pellets about 0.5 in diameter. Clinker is
then cooled and pulverized into a fine powder and mixed with gypsum and limestone. The result
is Portland Cement. Cement is so fine that 1 pound of it contains 150 billion grains.
Concrete countertops are made with a mortar mix consisting of one part cement and three
parts sand. Accelerators, superplasticizers, pigments and decorative aggregates affect
both the performance and final look of a concrete countertop.
Once the mortar mix has cured, the countertop is polished to remove the rough finish and
add an attractive sheen. Because concrete is porous, the countertops must be sealed
with a food-safe sealer.
Concrete or mortar countertops can either be precast in a factory, polished and brought
to your site like these products by Dex industries or they can be cast in place. There are dozens
of YouTube tutorials by DIYers with step by step instructions. Cast in place a messier
process, but it ensures that you have a perfect fit and seamless design.
Concrete can be colored in four different ways. Pigments are added to the wet mix so
that the color goes all the way through. Stains can be used on new and existing concrete.
Color hardeners strengthen and add intense color to the surface of concrete. Finally,
concrete dyes produce the most vibrant colors and have a wide variety of options.
Now let’s compare the physical properties of marble and concrete countertops. Marble
countertops are thinner, around 3 cm or one and a quarter inches. It weighs approximately
18 lbs per sqft. A standard 1.5” thick concrete countertop weighs approximately 23 lbs per
sqft.
Marble stays naturally cool, which makes it the perfect work surface for bakers. You can
work with chocolate, dough, and even ice cream without having to worry about it quickly melting
into a puddle. Concrete countertops don’t have this feature.
Marble countertops are usually lighter colored and are perceived to be higher quality and
add more value to a home. Concrete countertops are usually a darker gray color and have a
rough, industrial appearance. Unfortunately, they aren’t valued as much.
To test their porosity, I poured some red wine on both the marble and concrete samples
and let it sit for 2 full hours. After wiping it off, I could still see a permanent red
stain on the marble piece while the concrete piece looked good as new. Wine is acidic so
it ate away the top sealant and left it feeling rough and scratched. The professionally sealed
concrete piece wasn’t etched at all. Marble is a porous surface, which makes it highly
susceptible to stains. It requires frequent resealing every 6 months. Some light-colored
marble in a heavily trafficked kitchen may need to be resealed more often. For this reason,
marble is a better option for bathrooms, backsplashes and offices, while it might not be perfect
for kitchens. Concrete can be used in kitchens, but be aware that it is not a pristine looking
surface. It will change color, get scratched and stained and will patina over time. Even
if it is sealed, citrus juice and other acidic foods will etch concrete countertops.
Marble countertops can be honed, leathered or polished which adds a gloss sheen to the
surface. Concrete countertops can have a low-luster finish or an ultra smooth polished surface.
Concrete is also more customizable. You can add stones, colored glass or metal shavings
as aggregate.
Now let’s discuss their costs. They both have a wide range of costs per sq ft, depending
on quality and whether it's fabricated by a professional or by yourself. They both cost
around $50-$100 per sq ft.
Before we move on to the other differences between marble and concrete countertops, I’d
like to introduce the sponsor of this portion of the video. Brad Hedges is an architectural
sales consulting company based in Georgia. They help designers specify terrazzo, stair
treads, railings, pavers and resin wood laminates for architectural applications. They specialize
in high end residential and commercial projects like the Norfolk Southern Headquarters in
Atlanta. Custom concrete flooring and wall panels by DEX industries create a neutral
background for their lobby, conference rooms and offices. Head to bradhedges.com to check
out their detailed, exquisite work and contact them for your project.
Comparing their environmental impact is very tricky. If your marble countertops are locally
sourced, their carbon footprint will be smaller. Also, if you take care of them and regularly
seal them, they can last you a lifetime. The production of Portland cement is very energy
intensive, but you can use waste materials as aggregates in concrete countertops. Absolute
Concrete Works in Seattle uses a glass fiber reinforced concrete mix to make countertops,
fireplace surrounds, sinks and more. Because of its high strength, they can pour ¾”
inch thick countertops rather than 1.5” or 2” thick slabs. They also use 50% less
portland cement than regular concrete.
TV shows like this Rachel Ray segment encourage homeowners to turn their existing dark countertops
in light colored faux marble designs. DIY epoxy kits allow you to paint them white and
then add fake gray veining. A top clear sealant coat is supposed to protect the paint. It’s
a seemingly easy way to refresh your kitchen, but please be aware of the dangers of epoxy
including the strong fumes generated, the exothermic chemical reaction of the components
that melts plastic, the need to properly ventilate your work space and the short lifespan of
these cheap DIY products. Let me know if you have any personal experience using marble
or concrete countertops and if you prefer one over the other. I’ll link my Patreon
page in the description. If you can support me, I’d really appreciate it. A big thank
you to everyone already supporting me. Don’t forget to hit that like button, subscribe
button and the notification bell too. Thanks for watching. See ya.