As the vast advantages of UHPC become more popular in the construction and concrete industries, it becomes even more crucial for the contractors and builders to learn about the significant differences between various UHPC products available on the market. Others might assume that there could only be slight nuances between a single mix of this concrete compared to others. However, the truth is that these identified differences are quite significant.
In fact, selecting the best ultra-high performance concrete and construction scheduling software can determine the failure and success in meeting project requirements, deadlines, and budget. Here in this blog, we will take a closer look at what needs to be considered when assessing UHPC products and how versatile this type of concrete is when used in various concrete construction projects.
Defining UHPC – Why it is Not an Ordinary Concrete?
Ultra-High Performance Concrete (UHPC) is a new class of concrete developed in the past decades. This concrete has exceptional properties, both in durability and strength. It can also be used in accelerated bridge construction and structural rehabilitation, and any other applications.
UHPC premixes are superplasticizers, organic fibers, and powders, with Portland cement as the main ingredient. In its present form, UHPC is generally used for bridge components and bridge construction as it can address the connection issue of precast concrete construction. For instance, a study on UHPC structural loading shows that field-cast concrete can facilitate the construction of emulative bridge deck systems. Here is a list of UHPC “bridge applications”.
- Precast concrete piles
- Pre-stressed girders
- · Seismic retrofits of bridges
- Securing and blast mitigation applications
- Thin bonded overlays
- Field-cast closure pours for bridge elements
- Precast waffle panels for bridge decks
Moreover, the compressive strength of UHPC is ten times more than the usual and traditional concrete used today. Hence, it will only not bend easily and quickly under tons of loads and compression. While the conventional concrete has a ductile strength of 400-700 psi, UHPC has more tensile strength of 1400 psi. It is the type of concrete that is very durable even under extreme weather conditions. When the surface is finally abraded, the resistance is nearly twice as higher compared to the regular concrete.
How Does UHPC Change Construction Methods?
In some ways, UHPC is proven to improve bridges’ longevity and speed up the entire process. Yet, from the contractor’s perspective, the major question should be like “How much will it change the construction techniques and methods?” Furthermore, the utilization of UHPC in any construction projects might mean the following:
1. Casting and Cleaning
The casting activity is quite similar in regular concrete, yet it is independent of delivery and mixing. Hence, when cleaning UHPC, starting from smooth surfaces is generally easy. Using a simple knife, everything can work. However, if there is something for UHPC to bond to like nuts, dimpled concrete surfaces, and bolts, then jackhammers might be required to use.
No active steam will be required for the preliminary curing. However, within fourteen days of casting, all of the independently batched and discretized segments have to undergo a second-round cure at 90 degrees Celsius. The process has to last for 48 hours. But for UHPC, high-temperature curing isn’t harmful to the composition or matrix of the concrete. Additionally, it can also produce different reactions that can deeply hydrate the cementitious material and densify the system to achieve maximum strength.
There is no change from the contractor’s viewpoint if UHPC is chosen as the primary material for a component instead of another material. When it comes to methods and means, the status quo might continue for the contractors apart from the possibility of drilling holes. This task might require a surge in the number of drill bits utilized in the entire process.
4. Form geometry
Forming with ultra-high performance concrete has an additional dimension all because of autogenous shrinkage. It often occurs before the removal form tends to increase. It can prohibit reducing forms, yet it causes cracking. That is why it is necessary that the full attention is to free the shrinkage, especially during preliminary curing.
5. Utilization of Construction Crew Scheduling Software
Deciding to use UHPC for the current and next projects require enormous effort and extensive supervision. Hence, software solutions designed for project management are a great addition to the set of resources and tools to use. Time tracking, crew/labor monitoring, real-time collaboration, ease of accessibility, etc., are some of the best advantages and features this cloud-based software offers. On top of that, it is a user-friendly application that can be accessed anytime and anywhere.
8 Major Qualities to Consider when Assessing UHPC Providers
For concrete contractors who are set to prepare for their next projects, considering UHPC is a high-priority. But they have to keep in mind the other factors to consider, including UHPC providers’ selection. Here are the top items to bear in mind when choosing a UHPC mix for the next projects.
1. Batch Size
Apparently, several conventional UHPC products can only be mixed in small quantities, and it is no more than 50 pounds. Thus, it only requires constant mixing and measuring of various batches during any given project. If this is always the case, it will result in downtime for laborers and machinery. Be sure to search for a particular UHPC product that can be easily mixed in larger batches and meet the job demands.
It is often challenging to utilize UHPC for larger products, especially if it cannot be adequately poured. The mixture should be easy to flow and pump, primarily when it is used for larger-scale projects. Concrete contractors need to be keen on details, ensuring that the mix they pick can be poured easily.
Most of the new materials typically require new processes, tools, and equipment. While it is right for some UHPC mixes, a few available UHPC products can be poured and mixed using traditional machinery. However, make sure to follow the same process as a contractor will do for traditional crushed concrete. Doing so will remove the costs for new equipment and tools, keeping the participating workforce moving smoothly with the workflow they used to follow.
4. Mixing Time
The proper mixing time for any UHPC products often depends much, with several conventional mixes requiring up to 20 mins per batch. Concrete contractors have to be sure to consider the mixing time required when assessing any UHPC products since other options are all-time ready in just a few minutes. Implementing project management for construction is crucial to the overall development of the project. Thus, it is practical to consider advanced tools for more efficient project management.
The batch size is considered as one most significant factors that significantly impact consistency. Various small batches on some projects commonly have smaller margins of error, resulting in a lack of consistency in the last products. The variances have a negative impact both in durability and quality. Basically, UHPC can be made from large, and mass-produced batches usually do not have any consistency issue. Hence, it only proves that it is a much better option than other available products in the market.
While all UHPC mixes often provide gains in strength, several strength differences are identified across UHPC products and their mixes compared to traditional concrete. Apparently, it is the unique blend of combined fibers from the mixture that delivers strength. Ensure some providers that offer UHPC customization were creating a custom mix is one of the options.
Additional customization around leveling and working time can also be obtained by some dedicated UHPC providers, adding extra advantages to the project timeline and other specific project needs.
There are different ways to deliver the UHCP products onsite, and figuring out the best method is necessary. Providers tend to design batch plants whenever accommodating silo-style mixing and distributing more cost-effective and efficient larger batches. This type of provider is one of the best since they make UHPC products easy to scale for any given project, either small or large.
The products can be delivered within several increments, stretching from fifty-pound bags until they reach full tankers. It is straightforward to use and apply even to substantial infrastructure projects.
One of the primary benefits of UHPC is its strength compared to any traditional concrete. There is a set of testing that shows how strong some UHPC products are. These samples are being tested for a tighter strength at 14 and 48-hour marks. As a result, a final 28-day cure tightening strength was accomplished.
UHPC is revolutionizing the construction industry, bringing outstanding durability, versatility, strength, and more to the table. It is necessary to be reminded that some UHPC mixes should be selected thoroughly.
UHPC is proven to accelerate construction and reduce traffic impact during the construction process. Also, prefabricated bridge components should be connected with durable, strong, and straightforward installation materials. The great thing is, UHPC not only has an essential composite quality but also it possesses simplicity in its application.