How to double up production of precast concrete?

Task: On site production of precast wall panels
Concrete specs: 5000psi
Additives: Fiber and plasticizer
Aim: To increase productivity and output as well as avoid delays and inconsistency from the loacal concrete supplier.

In the middle of May 2020 Carmix Nevada was contacted by a San Diego based company dealing with production of precast concrete panels. The owner heard about mobile self loading mixers before and considered it as a solution to his problems.

At the time, he was buying concrete from a local batching plant and faced many related difficulties.

One of the issues was the waiting time which varied quite considerably. This resulted in loss of productivity and output.

The other matter was related to a specific mix design used for panel production. It is a 5000psi very dry mix with fiber and plasticizer addition. The effective life of concrete after mixing in with water is no more than 1.5 hours, however this particular mix design required it to be poured, vibrated and finished within 30 minutes from the time of production. This imposed a number of difficulties, the main of them being that a mixer would deliver up to 8 cubic yards of concrete at once and it was almost impossible to pour this much all at once.
Amount of concrete needed for one panel varies between 1.6 and 1.72 cubic yards.

According to the correct procedure, every panel has to be poured, than with the use of concrete placers, it has to be levelled and prepared for use of vibrating screed and concrete vibrator to get a smooth finish of the surface. All this takes quite a lot of time and to get the best result, panels have to be poured and finished one at a time. Unfortunately, working with a local batching plant delivering concrete for almost 5 panels at a time was a nightmare. Clients team was struggling to pour that much concrete and maintain desired quality of
finishing the panels.

Another problem was uniformity. One day mixer comes to the jobsite with certain slump of concrete which is suitable for pouring into the panel forms, the next day it`s too liquid or too dry, and there is no possibility to make any adjustments when concrete arrives for pouring.
Also timing was a crucial aspect. It was almost impossible to predict arrival of the concrete mixer. One day it takes 40 minutes, next day the wait time can be 3-4 hours. All these issues made it very difficult to plan work in advance.

The problems were obvious and the client started to search for suitable solutions. 

During our first phone conversation the client expressed concerns about the ability of Carmix to mix such a dry concrete in the required quantities and on time.

Fortunately we, as Carmix Nevada offer not only sales, spare parts and maintenance of Carmix self loading mobile concrete mixers, but also we have a rental fleet. This allows customers to test machines at their jobsite and see how Carmix can solve their particular problems without having to spend considerable amount of money and buy the machine.
After signing a leasing agreement we have organized transportation of Carmix 3500TC to the jobsite not far from San Diego, CA. Our technical specialists arrived at the jobsite together with the mixer to train the person who is going to operate carmix to produce concrete onsite. The actual training takes less than a day, especially if the operator has previous experience with front loaders, excavators or other heavy construction machinery.
We have spent two and a half days together with the client to ensure that Carmix is working at it`s full capacity and concrete is produced according to the requirements of the customer.

Carmix 3500TC, with it`s output of almost 4 cubic yards per one batch was an ideal solution for this project. It provided a choice of either producing 1.6-1.7 cubic yards enough for one panel, or mixing the full load and preparing enough concrete to pour two panels at the same time.

Water was stored in large plastic tanks on site and with the use of onboard water pump Carmix can get water into the mixing drum or into the onboard water storage tanks.

Cement was used in 94lb bags and was loaded into the bucket with the help of the metal blade.

Gravel and sand were stored in piles and self loading mixer was able to load the aggregates with the articulated shovel.

Considering mentioned above a full loading and mixing cycle of 3.5 cubic yards of concrete took around 20-30 minutes.

Another huge benefit of using Carmix at this project was its maneuverability and its turning drum. These features helped to facilitate concrete pouring compared to discharging concrete from conventional mixer.

Learn how carmix can help your project to save cost and time.
Give us a call and we will offer you a tailor made solution that will suit your particular needs.