How to Choose the Right Sand for Concrete

1. How to Choose the Right Sand for Concrete You might not give it much thought, but your concrete mix is just as important as the cement itself when it comes to determining the quality of your concrete structure, and it’s especially important when you’re working with structures that are exposed to harsh environments or those that you’re depending on to hold up over time. While there are lots of different ingredients that go into making the mix, one of the most important ones to pay attention to is sand, and especially if you’re using this in conjunction with aggregates. Here’s how you can tell which sand to use for your construction project. What’s the Difference Between Bagged and Bulk Sand? There are a few things you should consider when determining which type of sand is best suited for your project. First, is your sand a cold mix or hot mix? Cold-mix sand can be used straight from bag to concrete mix without any drying time—meaning it contains clay and enough moisture that it won’t crack after being installed. However, hot-mix sand typically has more sharp edges that need to be crushed down before use. The sharp edges are part of what makes a hot-mix ideal for installing on slopes. If you want your project to last longer, then cold-mix might be best suited for your needs. Sorting Through Grades of Sand There are numerous types of sand, and grading systems vary by country. As a general rule, coarse sands with a fine grain are best used in dry mix while finer sands are more common in cold-weather conditions. Sand that meets ASTM C 33 standards is most commonly used

2. in cold weather, as it retains its shape when wet. Once you’ve picked out your grade of sand, you should carefully read manufacturer instructions on how to handle it so that you can incorporate it into your project efficiently and effectively. For example, if your concrete is heated above 120 degrees Fahrenheit (48 degrees Celsius), make sure not to add water until after it’s been set or mixed; if not mixed properly, cold mix has a tendency to crack or fall apart over time. Cold-Mix vs Hot-Mix Asphalt While both cold-mix and hot-mix asphalt are used in road construction, these two asphalt types differ in how they're made. Cold-mix asphalt is mixed with sand and other aggregate at temperatures ranging from 70 to 130 degrees Fahrenheit (21 to 55 degrees Celsius). Hot-mix asphalt has a temperature of 1,000 degrees Fahrenheit (538 degrees Celsius) when it's mixed. Cold mix tends to be more economical than hot mix. If you're working on a small project that requires only a few tons of material, a cold mix may be ideal because you don't have as much wasted material due to heating. Do I Need To Add Water To The Mix? If you’re asking yourself, Do I need to add water to my sand and aggregate mix? or have another question about your cold-mix recipe, we can help. The short answer is no, since you’ll add water later when concrete is ready for pouring. You can ask us anything about your sand and aggregates needs through our chat widget below. When selecting a sand for concrete mix, you’ll want a blend of coarse sand (greater than 2 inches in diameter) and fine sand (less than 0.075 inches in diameter). Some general guidance: 1 part coarse aggregate = 4 parts fine aggregate + 2 parts cement. What’s Next After The Aggregate Choice? As a rule of thumb, almost all aggregates used in concrete should have less than 1% carbon content and be larger than 1⁄4 inch in diameter. But there are plenty of exceptions to these general rules. For example, with sand as an aggregate, you can also add silica fume to your mix. Silica fume is nothing more than very fine sand that’s rich in silicon dioxide; it helps prevent alkali-silica reaction (ASR) because of its high free lime content. Some other mixes combine different sizes of gravel for better interlock strength or add masonry cement for extra resistance against freezing and thawing.