Here are three ways JUNO XP can solve aggregate problems.
As we all know, concrete starts off life as a pile of aggregate floating in a soup of cement and water. Problems with the mix often lie with the aggregates. JUNO XP was developed by Surface Tech as an alternative supplementary cementitious material (ASCM) that can be used to partially substitute traditional cement binders, and the product has shown it can help solve three common aggregate problems.
JUNO XP restores creaminess when used with manufactured aggregates
Since manufactured aggregates can be irregular and angular in shape, they can overwhelm the paste in the concrete, making it unworkable and hard to finish.
This is due to the higher surface area common in manufactured aggregates, and it can occur whether the aggregates are dirty or clean.
Many concrete manufacturers compensate for the slump loss by adding water to make the mix easier to finish. But this remedy comes at the expense of undermining the hardened properties of the resulting concrete.
Because JUNO XP reduces the amount of water needed to preserve slump, it is an ideal addition to a mix using manufactured aggregates where increased workability and flowability are needed to meet the demands and specifications of the project.
“JUNO XP mechanically and chemically enhances the cementitious paste to increase resiliency,” says Dr. Jon Belkowitz, Surface Tech’s chief technology officer for concrete. “It’s the fine particle size, in particular, that plays an important role in the material properties of JUNO XP. The core technology found in the product employs cutting-edge advancements in mineralogy, combined with a graduated matrix.”
JUNO XP increases the service life of concretes made with reactive aggregates
When alkali aggregate reactivity (AAR) and alkali silica reactivity (ASR) occur in concrete, they produce a hygroscopic gel that absorbs moisture and causes expansion and cracking over time. This subsequently causes internal failure of the matrix, which leads to ultimate failure of the concrete before its intended service life.
The common remedy for AAR and ASR calls for the addition of Class F fly ash to the mix. Because it also forms additional paste volume in the presence of cement + water, fly ash can improve durability, strength and slump. Today, however, the availability of Class F fly ash is limited. This shortage is acutely felt in regions where reactive aggregates are common, or where non-reactive aggregates are not regionally available.
As an alternative to fly ash, concrete producers can now turn to JUNO XP to restore durability, strength and slump. Exhaustive testing, as well as real world applications, have shown JUNO XP can reduce the amount of traditional cement and fly ash needed in concrete, while improving fresh and hardened properties.
In addition to restoring the service life of the concrete, JUNO XP saves producers the cost of transporting less reactive or nonreactive aggregates from other regions. Better yet, JUNO XP will, in most cases, mitigate ASR enough to enable concrete suppliers to use aggregates that are available within their region.
JUNO XP provides forgiveness when working with dirty aggregates
The level of microfines in concrete aggregates can affect concrete in both the plastic and hardened states. Microfines affect concrete mixes in two ways. One, they have the ability to absorb large quantities of water; and two, they can react chemically to degrade the cement paste microstructure.
When working with dirty aggregates, concrete producers generally face challenges in achieving the desired slumps or air contents needed. Yet if extra water is added to increase slump, it can reduce the hardened performance of the concrete.
JUNO XP plays nice with water, making the paste more resilient by chemically and mechanically altering it. It allows the mix to tolerate dirty aggregates, or to decrease the amount of aggregate wash needed. Additionally, JUNO XP reduces the porosity structure of the paste and provides a more viscous formula that correspondingly results in a more workable concrete that is easy to finish.
“The proprietary and novel properties of JUNO XP change cement hydration at the molecular level to increase the strength (tensile and compressive) and the durability of concrete. And it improves the performance of concrete on other levels, including workability and shrinkage control,” Belkowitz says.
Got aggregate headaches? Take JUNO XP powder
Because JUNO XP is a powder, it can be easily incorporated into any conventional dispersion system — silo, hopper, supersacks, bags and dissolvable bags. Integration ease is what separates JUNO XP from other new technologies.
It can also save you money. Concrete producers can expect to see a reduction of 20 to 35 percent of the cost of conventional cement by adding JUNO XP to the mix. Savings and ease of use alone make JUNO XP worth considering.
Yet JUNO XP goes further by providing key environmental benefits. Since traditional cement production accounts for 88 percent of the emissions associated with the average concrete mix, JUNO XP provides a way to offset this pollution and provides a means to achieve LEED credits and an improved carbon footprint for your project. Reduction of cement in mix designs is a calculable formula recognized by ACI/ASTM for credits.
The ease of use — plus the dollar and environmental savings — come with no sacrifice in performance. All these benefits make JUNO XP a product worth investigating, particularly when working with aggregates that yield unworkable finishing qualities and concretes that fail to live up to expectations.