Pathway Material Technical Data

Quality Control 101: What Is a Sieve Analysis and Why Does It Matter?

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When selecting aggregate for commercial use, there are a number of tests the product goes through to evaluate its suitability for a certain application. Among these tests is a sieve analysis. A sieve analysis helps companies to evaluate aggregate for use as a quality product in pathway mixes, architectural and decorative precast concrete, epoxy resin applications, epoxy overlay, and much more. We’ve put together a quick summary that highlights the significance of sieve analysis and why it matters to the aggregate industry.   

Evaluating Aggregates for Their Intended Uses

The practice of sieve analysis is especially important for the performance of aggregates in their intended uses. Each of these uses will require a specific size or gradation of aggregate, including the percentage of material allowed for each sieve size in the gradation. This can be critical for the strength of the material, compaction of the aggregate, and the visual aesthetic and surface area of the stone.In other words, the process of sieve analysis assists with the gradation of aggregates.

What Is Gradation in Sieve Analysis?

The gradation of aggregates is the distribution of aggregate particles, by size, within a given sample. The purpose of gradation in this capacity is to enable compatibility of the aggregate with product control requirements, designs, and verification specifications.

Gradation via sieve analysis works particularly well for aggregates because of the shapes of the stones and particles. Material that is not somewhat spherical—say, closer to cylindrical—may not lend to successful sieve analysis.

Sieve Analysis: Step by Step

The procedure of sieve analysis starts with the stacking of sieves, or screens, from the largest to the smallest size. Typically, the mesh of these sizes can range from 1 inch or 25.4 mm to what’s known as the “No. 400” or .037 mm of an opening.

Then, the bulk aggregate is placed carefully on the top sieve and the material is screened through the various sieves and subsequently become separated by size. Aggregates that couldn’t pass through a ⅜” sieve screen, for example, will stay in that sieve while the others pass through until they’re caught in the proper sieve. However, simply dumping your aggregate through sieves is not enough for accurate parsing – that’s what sifters are for.  

Sifting Methods

Depending on your machinery, sifting can be a relatively painless and time-saving process. Mechanical sieve shakers will shake the stacked sieves, causing each stone and particle to fall to its coinciding sieve screen. Note that there are different methods for sifting, common methods include:

  • Horizontal sifting: where the sieves are sifted in a horizontal motion
  • Throw-action: a sieve method whereby vertical force combined with circular motions is applied
  • Air jet: uses a vacuum or other means of creating an air stream to transport and separate finer particles
  • Tap: circular, horizontal motions with frequent tapping  
  • Wet: uses water to support the sieving process, but is a far less common practice than the traditional dry methods  

Once sifted, each sized aggregate is weighed and noted as a percentage of the overall sample—that is, the percent of aggregate retained per sieve is noted as well as the percentage passed through that size (known as the passing aggregate). These details are then recorded, and the quality aggregate is sent for distribution where it will then await its new home. 

An Example: How to Read a Sieve Analysis

In general, specialty crushed stone products must have consistent sizes and fall within acceptable tolerances. For a real-life example of the sieve test as it relates to Kafka’s quality control, we’ll unpack the sieve tests as they pertain to our stabilized pathway mix.

Kafka Granite’s Stabilized Pathway Mix must adhere to specifications as outlined by the binder manufacturer, Organic-Lock.  With the gradation specification, there is an acceptable range and distribution of particle sizes that is to exist within the stone sample. While each sample and sieve will vary slightly, it’s vital that the samples for stabilized pathway mix fall within this range because a success ensures one of two things: the pathway mix is consistently well-graded, and it will compact properly.

Let’s take a closer look at the gradation specification for Stabilized Pathway Mix and how it works. First we must understand what U.S. Mesh sizing is. U.S. Mesh Sizing is defined as the number of openings per one square inch of a screen. Therefore, the larger the number, the smaller the screen size. The example below shows each sieve size translated to metric sizing, but you can also use a helpful screen size / sieve conversion chart. 

The first pass calls for 80-100% passing the #4 mesh screen. In other words, 80-100% of stone particles must fall through a #4 mesh screen. Then, 65-90% of the stone particles should pass through an #8 mesh screen. You can see the rest of the required pass percentages in the below table. Once you reach the bottom of the chart, you’ll see that 5-15% of the stone particles should fall through the #200 mesh screen, which is an extremely fine, dust-like material.. If this were a “clean” or “chip” aggregate, there would not be such fine material included in the mix. 

Sieve Sieve Size (mm) Percent Passing
4 4.75 80%-100%
8 2.36 65%-90%
16 1.18 40%-65%
30 0.6 25%-55%
50 0.3 15%-35%
100 0.15 10%-20%
200 0.075 5%-15%

 

It is important that the pathway mix meets the gradation requirement above; it is vital for the product’s functionality. In order for the binder to work properly, the surface to compact, and rain water to drain, the gradation must be consistent and within the defined tolerances.

This is, of course, just one of many sieve analyses we run at Kafka to check a product’s gradation, and only one of many tests used to analyze quality. Contact us to request a sieve analysis or other product information.

Resources

Wisconsin Natural Stone

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Kafka Granite began in 1979 when Wisconsin native Glenn Kafka bought a backhoe at a local auction and started laying tile for local farmers. Shortly thereafter, he took advantage of an opportunity to purchase a granite pit and found himself taking his next steps toward a multifaceted natural stone company.

Flashing forward to the present day – Kafka Granite utilizes quarry sites in both the United States and Canada. But the heart of our business remains in Central Wisconsin, where we manufacture our diverse aggregates for a wide variety of client needs and specifications.  

Wisconsin Is Our Home and Is Perfect for Our Industry

To find the right spot for Kafka Granite, Glenn Kafka never had to go far. Much of Wisconsin consists of a unique geological makeup which makes it a perfect home for us. The varying granite, marble, and quartzite available helps Kafka Granite acquire its large variance in natural stone colors.

In fact, our immediate area is rich in mineral deposits – providing us with the opportunity to have numerous hues on hand. Other states in our country offer less variance in natural stone. Within just a hundred miles of our Wisconsin location, you can find pink, blue, red, green, gray, and black granite, beige and gray limestone, and gold, gray, and purple quartzite.

Get to Know Our Products

Our range of materials can serve the demands of various industries and project types. From indoor commercial remodeling to outdoor siding and decorative landscapes, our 60+ color options and dynamic natural stone products are perfect for nearly any endeavor. Here are just a few of our products.

Specialty Aggregates

Aggregates for Precast Concrete Applications

Our precast aggregates come in a wide spectrum of colors and can be used for a variety of purposes, including architectural wall panels, pavers, pour in place concrete, and site amenities. These products featuring Kafka’s specialty aggregates are commonly used in hospitals, office buildings, stadiums, and other commercial locations.

Aggregates for Epoxy Resin Applications

We manufacture and supply specialty aggregates for terrazzo flooring, epoxy stone flooring, and manufactured quartz countertops, These customers need stone that meets specific specifications, while also being dry and dust free, allowing them to produce high-quality floors and countertops for residential and commercial applications. 

Aggregates for High Friction Surfacing and Demarcation

Kafka Granite produces specialty aggregates for use in epoxy overlays – perfect for roads, bridges, curves, crosswalks, bike lanes, bus lanes, and various streetscapes in need of better traction on surfaces. Our high-friction surfacing aggregates can withstand the harshest of Wisconsin’s weather conditions, providing efficient traction for your surface year-round.

Natural Thin Stone Veneer

Our natural thin stone veneer is a durable, nonstructural product that can be used in both outdoor and indoor projects. Benefits of choosing thin stone veneer include:

  • Lightweight: The lightweight nature of thin stone veneer makes it cost-effective and easier to ship in bulk. Its weight also makes for an easier installation – in fact, it can be installed without footings or support ledges.
  • Versatile and long-lasting: You can use thin stone veneer for a fireplace in a lobby or as a facade on a multi-story office building. Its natural durability also prevents excessive wear and tear from harsh weather and temperatures.
  • Easy application: While we still recommend hiring a professional for installation, note that thin stone veneer can make for a relatively easy application. With the right preparation, it can be installed over various surfaces, including concrete, metal, and plywood.  

Our thin stone veneer will look just as natural and beautiful as full stone veneer, and it comes in classic colors perfect for commercial and residential endeavors. 

Sports Turf Solutions

From our Wax Polymer Pathway Mix to Stabilized Ballyard Mixes, we are proud to manufacture a selection of softball, baseball, and golf course materials. Our ballyard materials enable safe footing and consistent ball hops, while our golf course solutions are designed to create easy to install, low-maintenance, erosion resistant, and dust-free pathways and out of play bunkers. 

Pathway Materials

We also offer alternatives to hardscape for pathway needs. We manufacture materials fit for garden paths, bike paths, courtyards, nature trails, and more. Not only do our pathway materials come in over 40 colors and have a natural look and feel, but they are designed to reduce mud, dust, and erosion. 

Landscape Supply

Looking to add to the beauty of your outdoor landscape? Our natural stone hardscapes include cut steps, drywall, and flagstones that will help you design a lasting landscape oasis, while our landscape stone, boulders, and rip raps are the perfect accent to round out your project. 

Learn More About What Kafka Granite Can Provide for You

For decades, Kafka Granite has helped local and nationwide businesses and contractors find the material they need to achieve their goals. Whatever your project, our state-of-the-art process allows us to crush and screen aggregates to meet the needs of your design or specification.

Thanks to our extensive selection, architects, stonemasons, designers, and contractors from various industries come to Kafka Granite with thin stone veneer, aggregate, and other natural stone needs. We offer a broad range of specialty natural stone products for an array of project demands and are always expanding our offering to meet the needs of our customers.

Whatever your situation, we can steer you toward the right product. Contact us today – our knowledgeable sales team is happy to chat through your project or provide you with samples.

Specialty Aggregate Colors

A Simple Guide to Kafka Granite’s Commercial Offerings

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From specialty crushed stone in over sixty different colors for manufacturing, to beautiful multi-colored, naturally round granite boulders for landscaping, Kafka Granite is one of the largest and most specialized producers of landscape and architectural aggregates. Having been a leading and established supplier of granite, quartz, marble and recycled materials for over three decades, many of the top architects, landscape architects, contractors, and manufacturers turn to Kafka Granite aggregates for variety of projects, including:

  • Architectural precast aggregates for exposed precast concrete office buildings, medical complexes, skyscrapers, sports stadiums, etc.
  • Specialty crushed aggregates and manufactured sands for manufacturing decorative precast concrete pavers, or bricks, and precast concrete amenities such as trash cans, tables, planters, etc.
  • Contemporary natural thin stone veneer in a wide variety of cuts and colors for both commercial and residential design
  • Over 60 colors of granite, quartz, marble, and recycled materials crushed, dried, and bagged for use in manufacturing epoxy resin countertops, tile, and terrazzo flooring.
  • Epoxy Overlay Aggregates for High Friction surfacing applications that provide high-friction, non-skid surfaces for bridge decks, entrance/exit ramps, curves, bike paths, and pedestrian crosswalks.
  • Bulk quantities of decorative landscape stone that includes various colors and sizes of crushed stone, round pebbles, multi-colored granite boulders, and decorative rip rap boulders.
  • Natural stone hardscapes including thermal-top steps, sawn cut drywall, and thermal flagstone, for a variety of functions and applications that elevate the beauty of commercial and residential properties 
  • Decomposed Granite pathway materials for a more natural alternative to traditional hardscape solutions such as asphalt, concrete or pavers.
  • Reduce golf course maintenance with Kafka’s erosion resistant Wax Polymer Pathway Mix and Bunker Sand 
  • Premiere ball yard infield mix, warning track mix, and mound clay available at a variety of price points to provide lower maintenance, better drainage, safer footings, and consistent ball hops.

With so many products available, sometimes it’s difficult to understand all of the choices, but we are here to help! The Kafka sales team is standing by to help with your next project, but this short guide might be a simple first step in answering many of your questions. Let us break it down:

Architectural Precast Aggregates

Architectural precast is one of the most durable materials used in the exterior construction of commercial buildings today. But it is the exposed precast stone aggregate that truly gives the final product its unique aesthetic. Architectural precasters are looking for the perfect combination of aggregate with a very specific combination of stone size, color, and strength to create the perfect end product. With a massive network of stone quarries throughout North America and the unique ability to meet any size specification, Kafka Granite has the perfect aggregate and will work with you to make your next project a success.

Decorative Precast Concrete Aggregates for Decorative Paver and Amenities Manufacturing

Concrete bricks and pavers are always a popular decorative hardscape solution. However, adding Kafka Granite’s naturally colored aggregates to your precast concrete mix has the power to make them even more unique, by adding visual interest to the face-mix. Many of the top producers of decorative precast concrete pavers, bricks, and amenities trust Kafka Granite as their aggregate supplier–especially for the specialized colors, sizes, and recycled content not found anywhere else. With the rise in popularity of permeable pavers, we also offer complimentary permeable paver grit that’s crushed to size to ensure proper drainage and durability in freeze/thaw conditions.

Thin Stone Veneer 

An elegant, nonstructural stone product fit for numerous applications, natural thin stone veneer can be used in indoor and outdoor renovations. Lighter in weight than full stone veneer, thin stone veneer is also cheaper to ship in bulk and can be easily installed without support ledges or footings. With proper preparation and installation by a professional mason, this product may also be adhered to a variety of existing surfaces such as plywood, paneling, concrete, metal, and more. Kafka Granite thin stone veneer comes in dozens of natural color choices and will hold up to weather and wear much better than manufactured, artificial stone alternatives. 

Epoxy Resin Aggregates for Countertop, Tile, and Terrazzo Floor Manufacturing

With the ability to crush, dry, and bag 60 different colors of granite, quartz, marble, and recycled materials, Kafka Granite has a long history of supplying crushed stone chips for manufactured countertops, tiles, terrazzo flooring, and other epoxy resin-based manufacturing. Many of the top producers of Manufactured Quartz Countertops use a variety of Kafka’s aggregates and recycled materials in their production. Furthermore, Kafka has a longstanding relationship with T&M Supply, who distributes Kafka’s aggregates for stunning terrazzo flooring solutions throughout the world.

Epoxy Overlay Aggregates for High-Friction Roads and Non-Slip Pedestrian Walkways

There are many times when traditional concrete and asphalt are simply unsafe for high traffic roadways and walkways.  During certain times of the year, these surfaces can become extremely slippery and unsafe, especially on bridge decks, sharp curves, and entrance/exit ramps. High Friction Surfacing is the perfect solution, with Kafka Granite’s Epoxy Overlay aggregates offering a high level of traction in all kinds of weather, while also being durable enough to withstand harsh freeze/thaw conditions. The epoxy overlay aggregates can also be used for Streetscape applications such as crosswalks, medians, sidewalks, and bike lanes to create a non-slip surface for pedestrians while also enhancing the aesthetics of the pre-existing hardscape.

Landscaping Stones and Boulders

Kafka offers a wide variety of decorative landscape stone and boulders that will provide the perfect solution for landscape designers and contractors. Offered in a variety of colors and sizes, use Kafka’s Decorative Landscape Stone to define walkways and driveways, to enhance gardens and flower beds, or to brighten heavily shaded areas. Kafka Granite also offers a beautiful array of naturally round, glacially deposited multi-colored boulders that range in size from 3-6-inch cobbles to massive boulders over 60-inches in diameter. Use round boulders, or consider the variety of Decorative Rip Rap boulders, for retaining walls, water features, ponds, shorelines, or simple, yet effective, accent pieces in your landscape design.

Natural Stone Hardscapes

Thanks to a wide range of uses and sleek, natural colors, stone hardscapes have the ability to seriously elevate the beauty of your property. From flagstone to retaining walls and stone steps, Kafka Granite is proud to offer stone hardscapes that serve your project needs. Some of our hardscape products include Sawn Cut Drywall, Thermal Flagstone, and Thermal-Top Steps. A thermal finish on the top surface of your hardscape can increase traction while maintaining the natural integrity of your stone. 

Pathway Materials

For pathways, bike paths, and other trail systems where a more natural look and feel is desired, consider a more organic material that is both aesthetically appealing and durable. Sometimes traditional concrete or asphalt just won’t do. The Standard Pathway Mix is made from decomposed granite or crushed stone, screened to a specific size to ensure a maximum compacted surface that retains firmness, flexibility, and permeability. Kafka also offers two additional levels of durability. The Stabilized Pathway Mix includes an organic binding agent for a stronger, more stable, and less erosive surface. Meanwhile, the Wax Polymer Pathway Mix is the best pathway solution for extremely high traffic areas or steep inclines, as it’s non-permeable surface allows water to bead off the surface, eliminating mud, dust, and erosion.

Golf Course Solutions

Kafka Granite has developed solutions specifically for golf courses. These products are designed to provide a natural look while being incredibly easy to install. They drastically reduce maintenance, mud, dust, and erosion. Durable, long lasting and lightweight, Kafka’s Wax Polymer Pathway Mix is perfect for golf course pathways. Not only is it appealing to the eye, it’s erosion resistant, easy to install, and dustless. Developed with the same technology, our wax polymer bunker sand was designed for out of play or target bunkers, and may be installed easily over preexisting bunker sand. It allows water to shed into draining systems without erosion. 

Ballyard Materials

Finding the proper materials for baseball or softball diamonds can be a nightmare; most of the traditional materials are too muddy, too dusty, and too high maintenance, which all take valuable time away from both the groundskeepers and players. However, Kafka Granite specializes in low maintenance, high drainage products that minimize mud and dust, while retaining the natural playing surface that players know and love. From standard high-drainage top dressings, to high-quality, professional-grade infield mixes and warning track mixes, Kafka Granite offers a variety of solutions for any price point: from the little league to the major league.

Kafka Granite Does It All!

Can’t find what you’re looking for? Just ask! After all, most of Kafka Granite’s products were originally developed to meet customer requests, and we are not limited to the product lines you just read about. We are a custom-orientated company, so whether your firm is trying to match an aggregate used in a pre-existing structure, meeting a unique size specification for your manufacturing process, or just making a statement with a completely unique, custom color combination, Kafka Granite will work with your team to make it happen.

Kafka Architectural Aggregates Color Chart

How Does Natural Stone Get Its Color?

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No two pieces of natural stone look alike—even if you’re comparing two pieces of granite extracted from the same quarry. This variation of color, pattern, and texture is part of what makes natural stone so unique and so highly prized as a building and landscaping material. If you’re on the lookout, you’ll notice it in a variety of projects, from chimney facades to public pathways. Currently, thin stone veneer is a particularly popular natural stone product for both commercial and residential projects.

But how, exactly, does natural stone get those striking colors, and why can’t you find the color you’re looking for in your area? Geology holds the answer to these and further questions.

What Causes Color Variations in Natural Stone?

When it comes to color variations in natural stone, it’s all about minerals. Take Wisconsin, for example. Kafka Granite’s home state has glacially deposited minerals to thank for the wide range of colors we see in our local stone quarries.

Minerals and other organic components that were present when rocks were being formed resulted in the rainbow of different colors that we see today. The exact arrangement and abundance of said components are what create the beautiful graining, textures, and varied hues that natural stone is so well known for.

Those various minerals and organic compounds all have different properties and chemical makeups, meaning that they all affect natural stone in different ways. Iron oxide, for example, creates a vivid red color, while serpentine can create a green coloration in stones like marble. The abundance of the mineral deposit will also determine how varied the colors are in a particular stone. You might be able to clearly see a mineral deposit in stone extracted from a certain part of a quarry, while other areas contain lesser amounts of the mineral and therefore fewer bursts of color.

Here’s a look at how minerals affect the hues of several common types of natural stone.

Granite

Granite, primarily composed of minerals and rocks like quartz and mica, is found in a wide range of colors across the country. An abundance of potassium feldspar will give a deposit of granite a warm, pink hue, while the presence of quartz will create that classic, milky-white tone. Thanks to its glistening tones, granite is an excellent option for interior and exterior thin stone veneer projects.

Marble

With zero impurities present, marble is largely white and uniform—but you’d be hard pressed to find any significant amount of naturally occurring marble that doesn’t contain color variations. The striking veined patterns that make marble such a popular natural stone are caused by deposits like feldspar and iron oxide.

Quartz

Quartz is a naturally clear stone, so the presence of any impurities will change its appearance. You’ll find this stone in just about every color you can imagine, although some are more common than others. Purple, yellow, and gray are just some of the hues you’ll come across when purchasing quartz stone products. 

Why Can’t I Find a Specific Color of Stone in My Area?

If you’re looking for a specific color of natural stone for your project, the good news is that there’s an immense variety of colors out there. The bad news is that you might find your own options somewhat limited, depending on the area from which you’re trying to source materials. 

Wisconsin’s unique geology makes it rich in naturally occurring decomposed granite, along with quartz and feldspar. But other areas of the country may lack some types of natural stone entirely, or they may have an overabundance of one color. The solution, then, is to locate a supplier of high-quality natural stone products, one who can source the color that matches your design.

Kafka Granite’s Natural Stone Products

Kafka Granite is proud to offer natural stone products in dozens of dazzling colors. We have so many hues on hand because our immediate area is rich in the mineral deposits that create them. As we mentioned, our state of Wisconsin is known for its naturally occurring decomposed granite in fiery reds and golds—but that’s not all we have to offer. We’ve spent over 40 years scouring the country for different colors of natural stone. 

Today, we source our natural stone products from quarries across North America. This allows us to offer a color and product selection that you simply won’t find anywhere else. So if you’re wondering why you can’t find pink granite or anything other than gray limestone when sourcing materials for your next project, now you know: your area likely doesn’t have any deposits of the type or color of natural stone you’re on the hunt for. But if you have your heart set on a specific color for your installation, we’d be happy to help. 

Looking for the Perfect Color of Natural Stone for Your Next Project?

If you’re having a hard time finding the right natural stone for your project, don’t settle. Instead, contact Kafka Granite today. Architects, designers, stonemasons, and more come to us for our extensive selection of specialty aggregates, thin stone veneer, and other natural stone products. If you’re not quite sure what you’re looking for, our knowledgeable sales team is here to help. We look forward to helping you incorporate the beauty of natural stone into your next project.

Quality Control 101: What Is Specific Gravity?

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So far, in our quality control series, we’ve discussed Mohs hardness and absorption—but there are still many other factors that play a role in creating specialty aggregates, natural thin stone veneer, and other products that will last. Today, we’re diving into the importance of specific gravity and bulk specific gravity in stone. Let’s take a look at what this physical property can tell us, why it’s so important, and how it’s measured.

What Is Specific Gravity?

Specific gravity is a ratio of the mass of a substance to the mass of the same volume of liquid (typically distilled water). This physical property plays an important role across a wide range of processes, from biological processes like kidney function to product performance. 

You may have also heard this property referred to as “relative density.” The word “relative” should hint at the fact that specific gravity is a unitless measurement. To make sense of this property, measurements must be compared against a standard. For solids and liquids, that standard is water at its most dense (about 39 degrees Fahrenheit), while gases are measured against room temperature air.

As water is the typical standard, it is understood to have a specific gravity of 1. A specific gravity below 1 indicates that a substance is less dense than water and will therefore float in the liquid, while a specific gravity greater than 1 means that the substance is more dense and will sink. Specific gravity in natural stone ranges from 2 to 3, meaning that stone is two to three times denser than water.  

Water Absorption and Bulk Specific Gravity in Stone

Specific gravity doesn’t exist in a vacuum, however; when it comes to the performance of natural stone products, other physical properties must be accounted for. Water absorption and specific gravity are two properties that go hand in hand.

All types of natural stone are porous to some degree, meaning that they will absorb a certain amount of water. Absorption allows us to assess that porosity, which in turn allows us to evaluate how well a stone will withstand weathering and structural stress. In general, denser stone is less porous. Because water absorption is measured as a percent by weight, however, a low-density and high-density stone can have the same absorption capacity—but the higher-density stone will actually absorb more water by volume. 

To allow for this caveat, we measure bulk specific gravity. This property takes into account a stone’s absorption capacity, giving us a better understanding of how strong the resulting product will be, how it might be affected by the freeze-thaw cycle and other natural forces, and what it can realistically be used for.

Specific Gravity and Quality Control

So, how does specific gravity in stone relate back to quality control? When it comes to natural stone products, consistency is key. Specialty aggregates used in architectural precast, decorative precast, and other manufactured products need to meet specifications for a particular application or installation. At Kafka Granite, we make key measurements like Mohs hardness, specific gravity, and absorption available directly to our customers, so that they can make the most informed decisions when sourcing materials for their projects.

Even non-load bearing products like natural thin stone veneer have to hold up to the installation process, the elements (if exterior), and forces like heat and changes in humidity. This means that every masonry unit needs to fit into an acceptable range of physical properties, from Mohs hardness to bulk specific gravity. 

How Is Specific Gravity in Stone Tested?

It’s not enough to simply be aware of standards—those standards need to be met every time. Kafka Granite adheres to ASTM material specifications for our stone products. Samples of our dimension stone are sent out for a number of tests, including ASTM C97: Standard Test Methods for Absorption and Bulk Specific Gravity of Dimension Stone. This particular assessment is used to measure both absorption capacity and bulk specific gravity for all types of dimension stone except slate. 

Absorption is up first. At least five test specimens are dried for 48 hours in an oven to ensure they’re completely free of moisture. Their dry weight is recorded, and they are then submerged in water for another 48 hours to make sure they’ve naturally reached their absorption capacity. When fully saturated, the samples are weighed again. The percentage difference between these two values is the absorption capacity.

To determine bulk specific gravity, the saturated specimen is suspended by a wire in air and weighed. The process is repeated with the stone suspended in water. The difference between these two values is the bulk specific gravity, which can then be used to determine density.

The testing process is similar for our specialty aggregates, but it’s important to note that, unlike dimension stone, aggregate or crushed stone isn’t required to conform to any one standard. However, this data determines whether crushed stone is appropriate for a specific application—so it still needs to be collected. Samples of our specialty aggregates are subjected to a similar process of drying, soaking, and weighing to determine both their absorption and specific gravity.

Kafka Granite’s Commitment to Excellence in Stone Products

Our decades of experience in the industry have made it clear to us that architects, designers, stonemasons, and others need high-quality specialty aggregates and masonry units that will hold up under stress and against natural forces. At Kafka Granite, we’re committed to providing consistent, useful products that fit perfectly into a project. If you’re searching for thin stone veneer or other natural stone products, reach out today. We’re always happy to answer any questions you may have.

Quality Control 101: What Is Absorption?

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Here at Kafka Granite, we’re dedicated to providing high-quality stone products—but that’s not the only thing that makes us an industry leader. Our dedicated team is constantly seeking out colorful new deposits and developing innovative uses for natural stone and products to meet the ongoing needs of our customers. We’re also happy to share our technical knowledge. To that end, we’re diving into the next topic in our quality control series: absorption. 

In previous installments, we’ve talked about the overall importance of quality control, dug a little deeper into Mohs hardness, and specific gravity. Now, we’ll be looking at what absorption is, how it’s measured, and why it matters to the end-user.

Why Does Absorption Matter?

Absorption is the percent by weight increase in the mass of a material when water is absorbed into its pores. (This does not include any water adhering to the surface of the material.) This acts as a measure of a stone’s porosity, which can tell us quite a lot about how durable that stone will be for a particular installation.

If you’re wondering exactly why water absorption matters in natural stone products, know that it all comes back to quality control. Different absorption levels determine how well a specific type of stone will withstand weathering and structural stress, and, by extension, how a product can be used. It’s essential that the qualities of a stone match the needs of the application; otherwise, your project simply won’t last.

Absorption capacity is particularly important in natural stone products that will be exposed to the elements and undergo the freeze-thaw cycle. If you’re creating a building facade from natural stone, for example, you’ll need to select an appropriate type of stone—one that is durable and not overly porous. If your material absorbs too much water, you’ll find it much more vulnerable to freezing weather. 

As another example, if you’re sourcing decorative aggregates for the face mix of your pavers, you should opt for an aggregate mix with a lower absorption. Continued freeze-thaw cycles and other forces will make aggregates with higher absorption levels more likely to break down over time, eventually compromising the integrity of the paver itself.

Finally, absorption can also tell us about a stone’s stain resistance. To protect the integrity of your installation and reduce the risk of your material becoming stained over time, it’s essential to choose a stone with a low water absorption.

How Do You Test for Water Absorption of Stone?

Water Absorption of Dimension Stone

Dimensional stone sold for commercial use must meet certain criteria across a number of categories, including absorption, specific gravity, and compressive strength.

ASTM International is a non-profit organization that develops both material standards and testing methods for products and materials throughout numerous industries. ASTM C97: Standard Test Methods for Absorption and Bulk Specific Gravity of Dimension Stone is used to test absorption capacity for a variety of types of dimension stone, such as marble and granite. 

Here’s a brief look at how the test progresses:

  • Five or more test specimens are prepared.
  • The samples are dried in an oven for 48 hours to ensure they are completely free of excess moisture. 
  • When totally dry, the specimens are weighed.
  • Next, the samples are submerged in water for another 48 hours to make sure they’ve naturally reached their absorption capacity.
  • When completely saturated, the samples are weighed again.

The absorption capacity of each sample is determined by calculating the difference between the fully dry and fully saturated weights. The resulting value, expressed as a percentage, gives us one piece of the puzzle for determining whether a type of stone is appropriate for a specific application.

Along with testing methods, there are ASTM specifications to which natural stone products must adhere. The standard requirement for water absorption in granite, for example, is .4 percent, while marble is .2 percent. 

It’s important to note that the absorption capacity of each type of dimension stone is actually a range, rather than one number. Absorption capacity in granite typically ranges from .8 to .01 percent, while marble goes from .8 to .04 percent. This means that a portion of natural stone sold on the market will fall outside of ASTM specifications. 

This brings us back to the essential nature of quality control. Remember that the most affordable option may not be the best option for your project—in fact, specifying low-quality natural stone products may actually end up costing you more in repairs and replacements in the long run. If you ever find yourself in doubt, be sure to ask your supplier for proof of ASTM testing.

Water Absorption of Crushed Stone

Our crushed stone is also regularly tested for absorption, Mohs Hardness, and specific gravity. But unlike dimension stone, there is no universal standard for water absorption of aggregate or crushed stone. Instead, organizations or businesses typically have specifications for materials they use in different projects. The Wisconsin Department of Transportation, for example, has a set standard for epoxy overlay aggregates. It’s essential that materials used in projects like high-friction surfacing installation meet these specifications. Otherwise, the aggregate will break down—reducing traction and failing to perform. 

To ensure that an aggregate meets the requirements for a particular application, samples are tested according to ASTM standards, such as ASTM C127: Standard Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate. 

The method for testing water absorption in aggregate or crushed stone is similar to that of dimension stone:

  • Aggregate samples are first dried to remove any excess moisture.
  • Once dry, the oven-dry density of the aggregate is measured.
  • Next, the samples are soaked in water for a prescribed period to ensure that they reach maximum absorption capacity.
  • Finally, the soaked samples are used to determine the saturated-surface-dry density and absorption.

High-Quality Stone Products From Kafka Granite

When you purchase specialty aggregates or other natural stone products from Kafka Granite, you can rest easy knowing the materials you receive will be of the highest quality. To further demonstrate our commitment to transparency and quality, all test data is available to our customers upon request.

We pride ourselves on our attention to detail and continuous pursuit of excellence—and we’re always happy to discuss your newest project. If you have any questions about our range of products or specifications, feel free to contact us today.

Moh's Hardness Test Example

What Is Mohs Hardness?

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We’ve touched on the importance of quality control in stone products before—after all, consistency is critical throughout the process of manufacturing precast concrete aggregates and other specialty natural stone materials. Today, we’re diving even deeper into one of the factors that contribute to a stone’s inherent quality: Mohs hardness. Here’s some information on the history of the measurement and exactly what it means for consumers. 

A Quick History of Mohs Hardness

We have Friedrich Mohs, a German mineralogist, to thank for the Mohs scale of mineral hardness. This essential scale is used to measure the scratch resistance of a material like quartz or granite. Possible measurements range from 1 to 10, with 1 indicating the softest material and 10 the hardest.

Mohs created his scale in 1812 as a way to identify specific minerals. By scratching a specimen with one of ten reference minerals, a person could identify the relative hardness and, potentially, the exact type of mineral they were dealing with. Geologists in the field continue to use this method for identifying minerals. At times, hardness picks are used in place of reference minerals. In a pinch, ordinary objects like glass, a knife blade, or even your fingernail can be used to determine the relative hardness of a mineral. 

How Does Mohs Hardness Affect the End User?

The Mohs hardness scale is particularly important to Kafka Granite’s industrial customers, such as manufacturers of terrazzo flooring. Depending on what the aggregate is being used for, there may be an industry specification or product standard that states how hard the stone needs to be.

Continuing with our terrazzo example, those applications typically call for a softer stone, because it polishes easier. Marble is one excellent option here. On the other hand, manufacturers of architectural precast wall panels or decorative concrete pavers usually prefer to use aggregate made from one of the harder stones, because they are more abrasive—and they’re looking for an exposed aggregate finish that will last a lifetime. 

This abrasive quality allows harder stone products to stand up to harsh environments. Since terrazzo flooring is typically found indoors, it does not face the same elements of freeze/thaw, snow removal, and vehicular traffic that epoxy overlay streetscapes may be exposed to. Exposure to both natural elements and human traffic can play a significant role in the breakdown of a material.

Mohs Hardness and Construction Specifications

Before embarking on a project, manufacturers need to know that their chosen material meets certain industry standards or requirements. Depending on the product being manufactured, such as high-friction surfacing, there may be stringent specifications that need to be hit—both to ensure the integrity of an aggregate and the longevity of the finished product.

Take epoxy overlay aggregates, for example. Hardness is an extremely important quality for products made from these materials. The Department of Transportation (DOT) has a number of exact requirements for the types of stone they use in high-friction surfacing applications, including size and hardness of the aggregate. For obvious reasons, the DOT wants the stone to wear down as slowly as possible over time. A harder aggregate allows the final product, whether it be an entrance ramp or a bridge deck, to retain its integrity.

Sourcing stone that meets stringent specifications is no easy task, particularly if you’re searching for a particular color. Luckily, Kafka Granite offers a wide range of products with different levels of hardness. Whatever you have in mind, we’ll work to find a stone that matches your vision. You may only know that you need a hard, gray stone for your manufacturing project, for example. While we do have gray marble, we’re also able to supply gray granite that would better meet the needs of your project.

Mohs Hardness and Cost

Quality control in specialty aggregates is essential, but it’s not the only factor that will determine your choice of supplier. Hardness also has a direct effect on the equipment being used to process stone. More abrasive stone is harder on machinery and will eventually wear it down, while something that’s softer has less of an impact. This, in turn, affects cost—and potentially your ability to source certain materials. Marbles are more affordable to produce than quartz, for example. Ideally, industrial manufacturers will be able to work with their aggregate supplier to source material that both meets specifications and fits within their set budget.

High-Quality Aggregates for Your Next Building Project

Kafka Granite is proud to be one of the largest manufacturers and suppliers of specialty aggregates in the country. We offer over 60 varieties of crushed marble, quartz, granite, and recycled materials. If you’re searching for a specialty aggregate for use in architectural precast concrete, pavers, terrazzo flooring, or any number of natural stone products, contact us today to learn more about how we can crush and screen aggregates to your desired specifications.

The Geology of Natural Stone

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Designers, architects, and stone masons get to see quite a variety of stone products, from specialty aggregates to natural stone veneer. Even more people get to see the end results of Kafka Granite’s products—in the form of building facades, bridge overpasses, golf cart pathways, and more. But have you ever wondered about where that stone comes from, and how it came to be? Where, exactly, do we get these striking colors and high-quality material? 

Today, we’re backing up a few steps to take a look at the geology of natural stone. And don’t worry if you don’t remember anything from your middle school geology class—we’ve got you covered with this peek into the rock-solid foundation of our industry.

Where Does Natural Stone Come From?

Geology is an earth science that deals with understanding the structure of the planet. It also holds the key to every natural stone product out there. Before the Earth was a solid mass dotted with features like oceans and volcanoes, it was a ball of mineral gases. Natural stone is the result of those mineral gases solidifying and being compressed over millions of years. 

As the Earth’s crust solidified, heavier minerals were pushed towards the core of the planet, where they were subjected to intense pressure and high temperatures. Eventually, these newly solidified minerals were pushed upwards towards the surface, where they formed rock beds. Some of these deposits became the very quarries from which we extract our own natural stone today. 

3 Rock Types to Know

Quartz, granite, limestone, and marble are just some of the natural stones that we use in our products, but these various kinds of rocks can all be classified into three main types.

Igneous

To put it simply, igneous rocks were here first. This type of rock is created when liquid magma or lava cools down and becomes solid. If that process takes place below the surface of the Earth, it results in intrusive igneous rocks, like granite. But if the lava erupts and cools on the surface, we’re left with extrusive igneous rocks, such as basalt. You’ll find these kinds of rocks everywhere from basins to deep in the oceanic crust.

Sedimentary

Sedimentary rocks are fairly self-explanatory: they’re formed by solidifying sediments, such as volcanic ash. The distinctive mesas that litter the landscape of the American Southwest are a prolific example of sedimentary rock. The exact nature of the sediment determines the type of rock that is formed. Clastic sedimentary rocks, such as shale and sandstone, are created from pieces of pre-existing rocks that become compacted. Organic sedimentary rocks form from plant and animal debris being compacted over millions of years, while chemical sedimentary rock is created by dissolved minerals depositing and solidifying from water.

Metamorphic

Again, the name offers a hint: metamorphic rocks were once igneous or sedimentary rocks that underwent a transformation. That transformation involved extreme conditions, like high heat and pressure, that changed the chemical composition of the rocks. Metamorphic rocks include marble and quartzite, two popular choices for specialty aggregate and stone product manufacturers.

How Does Natural Stone Get Its Color?

If you’ve worked with natural stone before, you’ve likely noticed that no two pieces are exactly the same. In fact, this is one of the major draws of natural stone as a building material; the color variations add a kind of character that is difficult to replicate with man-made products. 

So, where does natural stone get its array of colors from? It’s all thanks to the nature of the minerals and other organic components that make up each type of stone. Depending on the exact minerals and the way in which they settle, blocks of stone extracted from the same quarry can vary greatly in color, texture, and pattern. Marble, for example, is widely known for its veined pattern. Those veins are caused by deposits like iron oxide and feldspar. The “purest” marble is largely white and free of color variation, but particular varieties are actually sought after to lend a certain look or color to a project.

Applications of Natural Stone

It’s worth noting that different types of rocks are useful for different building purposes, depending on their hardness and other key physical properties. There are ASTM Standards set out that describe the minimum and maximum specifications for a variety of natural stone types, which is invaluable for quality control. 

Today, natural stone is extracted from quarries around the world—Kafka Granite owns a number of them across North America. While our business isn’t nearly as old as the rocks that we crush into specialty aggregates, our decades in the industry have shown us that there are nearly endless uses for natural stone. The material is ideal for thin stone veneer products, where all the color variations of a stone can be put on display. Natural stone can also be used in the creation of retaining walls, accent pieces, pathway mixes, and a whole host of other applications. 

Incorporate the Beauty of Natural Stone Into Your Project

Whether you’re an architect seeking a solution for a large commercial project or a designer planning out a rustic, farmhouse-style home, Kafka Granite has the right product for your unique needs. We’re eager to help you find the ideal natural stone product for your project. Contact us today to speak to a knowledgeable sales representative.

The Unique Geology of Wisconsin

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Though Kafka Granite sources stone from quarries across the continent, we’re proud to call Wisconsin our home—and the wellspring of many of our beautiful products. But what, exactly, makes this great state the perfect spot for our business? 

Essentially, it’s all in the geology of the area. We’ve put together an overview of the thousands of years of history and natural forces that have made Wisconsin’s geology so unique today. Read on to learn more about this fascinating state.

Wisconsin Stone Over the Centuries

Wisconsin’s uncommon geology didn’t happen in a year—or even a century. It took hundreds of thousands of years for Earth’s cooling and heating patterns to transform the area into what it is today. More specifically, we have glaciers to thank for the vast majority of Wisconsin’s mineral deposits and topography.

The Wisconsin Glaciation

About every 100,000 years, the planet goes through a long period of cooling, followed by a shorter period of warmth. The last occurrence of this cycle, known as the Wisconsin Glaciation, began about that long ago—with the Laurentide Ice Sheet advancing across North America. Large swaths of Wisconsin became covered in ice, which was diverted and interrupted by the natural topography of the area. 

It took thousands of years for the ice to halt its approach and for the glaciers and sheets to melt or retreat from Wisconsin, but that slow process left us with a natural landscape unlike anything else seen in U.S. geology. The shrinking Laurentide Ice Sheet left behind the many lakes and rivers that characterize parts of the state, as well as a wide variety of glacially deposited minerals—the very minerals that create many of the colors in Kafka Granite’s collection!

A Wealth of Minerals

Wisconsin contains deep deposits of iron and other ores, which have characterized the state—just look at the University of Wisconsin’s mascot, Bucky Badger, an homage to the local lead miners of the early to mid-1800s. But you can also find deposits of minerals and gemstones from A to Z across the length of the state. Quartz and calcite are just two extremely common finds.

Decomposed Granite in Wisconsin

Wisconsin’s unique geologic makeup, coupled with thousands of years of natural erosion, also resulted in large deposits of decomposed granite (DG) throughout the state. When feldspar, one of the main components of granite, breaks down, it results in flaking, crumbling material that can be further crushed for projects like pathways and baseball fields. Wisconsin boasts a variety of hues of naturally occurring decomposed granite, from bold reds to vibrant golds.

Decomposed granite mining is limited to certain geographical locations throughout the country, but Wisconsin is particularly rich in this material. Today, DG is extracted from the ground, then sent through a screening process. If needed, this natural resource can be crushed to specific sizes and gradations to meet specifications for a particular mix or project. 

What Does Wisconsin’s Geology Mean to Kafka Granite?

Thanks to the rich landscape created by the last Ice Age, Wisconsin offers an invaluable variety of materials, from natural round boulders to crushed quartz, granite, and marble in a startling range of colors. This selection enabled the rapid growth of Kafka Granite—because we were able to source and acquire so many different colors quickly, and in close proximity to our home base.

A Variety of Colors and Stone Products

This level of variety is not normal in much of the country. Head to another state, and you’ll see nothing but gray limestone for miles. Some areas of the country may not have any granite at all, or may only have one such deposit. It’s not easy to source all of these colors if you’re in the middle of Kentucky, for example. 

Wisconsin’s geology—and that of its surrounding states—allows Kafka Granite to source materials like black, pink, and gray granite, or gray limestone, all within 200 miles. In Pennsylvania, you’ll find more gray granite than you can use, but you won’t find the same range of other products and colors. 

It’s that level of convenience that has allowed us to meet the needs of architects, designers, and stonemasons around the country. In fact, about 85 percent of our colors are sourced from Wisconsin or the Upper Peninsula. 

We have an immense variety of naturally occurring materials, which you can even pick up on from the comfort of your car. The next time you’re in the area, take a drive around the state—notice the shoulders of the road, which are created from whatever stone is locally abundant. You’ll see shades like purple, gray, and green, all of which will tell you that there’s an abundance of stone that color in the area. Around our facility, you’ll notice plenty of gray and black granite.

Natural Stone Products From Kafka Granite

We’re immensely proud of the hard work and entrepreneurial spirit that has made Kafka Granite a leading manufacturer and supplier of specialty aggregates and other building products. Clearly, beautiful, rugged Wisconsin has played a pivotal role in the growth of our company over the years. Not only is it home to our crushing facility; but Wisconsin’s geology means that it offers plenty of natural resources and mineral deposits to satisfy the high demand for unique colors and products.

If you’re looking for natural stone products in a wide variety of colors and sizes, you’ve come to the right place. Contact Kafka Granite today to speak to a knowledgeable sales rep about your project.

Kafka Granite manufacturing

The Importance of Quality Control in Stone Products

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The importance of quality control throughout the natural stone quarrying, crushing, and fabricating process can’t be overstated. In fact, all quality stone products require a certain level of testing and oversight during their manufacturing process. Why? Because in order to create reliable, manufactured aggregates and other stone products like thin stone veneer, you need to start—and finish—with high-quality, consistent material. 

Whether you’re sourcing quality architectural aggregate or commercial landscaping materials, you need to be sure that you’re getting the best material for the job. That quality assurance you’re looking for starts as soon as natural stone is extracted from a quarry and extends throughout the manufacturing process. 

Kafka Granite supplies products that are used for a wide range of applications, such as architectural precast concrete, terrazzo flooring, manufactured quartz countertops, epoxy resin tile, and more. But we didn’t become one of the largest manufacturers and suppliers of specialty aggregates and other stone products in the country through sheer luck—our work requires high-quality materials and careful adherence to set standards. Here’s why it’s so important to monitor and control the quality of stone products.

Why Is Quality Control Critical in Granite and Other Natural Stone Processing?

Not all quarried stone is the same. The quality of the natural stone you source for a project will play a significant role in the overall look of the finished installation—and its continued performance. Your completed building facade might look stunning as the mortar dries, but how will it look five years later? What about five decades? Natural thin stone veneer, for example, should weather beautifully and retain its structural integrity over time. But imposter products, or artificial stone passed off as natural stone, will not yield the same results. 

Price is a factor in any project, and you may be tempted to go with the cheapest option around. But that road may lead to ruin in the form of imperfect stone products that don’t stand the test of time. For instance, precast concrete manufacturers need consistently sized aggregates to use in their mix designs, or their machines will produce varying results—rather than uniform product. Consistency is also critical in pathway materials. These mixes need to meet a certain gradation specification in order to work properly with their binders, and a poorly graded aggregate or incorrectly mixed binder will affect the outcome of the project. Before you get taken in by the price tag, be sure to ask your supplier for the specifications of their products, so that you can ensure you’re getting reliable materials.

What Goes Into Creating Quality Stone Products?

At Kafka Granite, we pride ourselves on producing architectural and landscape aggregates, along with specialty building stone products, that meet industry standards and perform admirably in a wide range of projects. Let’s take a quick look at what goes into the manufacture and installation of quality stone products.

Industry Standard Tests

To remain compliant and produce reliable products, manufacturers need to adhere to quality assurance specifications, regulatory standards, industry standards, and any other regulations that pertain to their natural stone products. A number of these standards are set down by ASTM International, a non-profit organization that develops technical standards for materials and products across a wide range of industries. 

Kafka Granite runs industry standard tests on all of our stone products, evaluating our crushed stone for criteria such as absorption, Moh’s hardness, and specific gravity, as well as regular sieve analysis. All of our thin stone veneer is tested for ASTM C615, the Standard Specification for Granite Dimension Stone. This test data is made readily available to our customers.

Installation Education

We don’t keep our knowledge to ourselves. Education is crucial to the proper installation of many of our products, both to ensure efficient use of the installing contractors’ time and to create a beautiful final result. When working with contractors on installations, we make sure they have the knowledge needed to get the job done correctly. That includes an understanding of the proper conditions under which to install a certain product and the proper tools needed for the job. Our Stabilized Pathway Mix, for instance, should have an 8-10% moisture content for ideal installation. We recommend the snowball test or step test to make sure that the mixture has been prepared properly. We also provide information on the amount of subgrade you’ll need, as well as base construction, surface watershed management, spreading, and compaction.

Innovation

As a leader in the specialty aggregate industry, we are constantly making strides in new applications and manufacturing processes that can improve products while maintaining quality. We work closely with our industrial and manufacturing customers to source aggregates that perform best with their processes, ensuring that they receive the materials they need to produce excellent finished products. And when it comes to pathway materials, Kafka Granite is proud to source some of the best binders in the industry. We recently sourced a polymeric wax that is proprietary to Kafka Granite. Our Wax Polymer Pathway Mix is currently patent pending. This particular pathway mix has proved extremely useful on golf course pathways and other pathways that need to withstand both heavy erosion, but maintain a natural look and feel..

Exceed Standards With Kafka Granite

Here at Kafka Granite, we put time, effort, and a lot of research into creating high-quality crushed aggregates and specialty building stone products. We’re proud to adhere to all industry standards and act as an example of manufacturing excellence in the specialty aggregate and crushed stone industry, and look forward to providing classic and innovative stone products for years to come. Give us a call today—we’re always happy to answer questions about our products, help you with a unique project, or provide samples.