Free DIY eBook · 41 pages
DIY Concrete Benchtop: Cast Your Own, Start to Finish
Our free DIY concrete benchtop eBook takes you from an empty kitchen to a sealed, installed GFRC top using the MACt Benchtop Kit. It is written for first-timers and follows the job in the order you will actually do it.
41
pages, photo-led
7
steps, plan to install
~2 wks
mould to installed
Free
PDF by email, instant
Free PDF by email
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- Every step from template to install, with photos and diagrams
- The exact recipe, the mixing order and the wait times
- 18 defects, what causes them and how to fix them
A 25 mm Benchtop That Looks Solid, Cast in Your Own Garage
Strength from glass fibre, not steel
A traditional poured concrete benchtop is thick, heavy and relies on steel reinforcement. GFRC (glass fibre reinforced concrete) gets its strength from alkali-resistant glass fibres instead, so a 25 mm top is strong enough for a busy kitchen.
Pre-proportioned and silica-free
MACt GFRC Premix is pre-proportioned, so you never measure sand or cement, and it is silica-free, which removes the silica dust hazard from mixing, cutting and sanding.
Cast in your own garage
A 25 mm top weighs about 57 kg per square metre: light enough for two people to carry in and fit, and cast on a flat table in a garage or shed.
Inside the eBook
What’s Inside the DIY Concrete Benchtop eBook
Most first-time mistakes are decided before any mix is made: in the mould, the timing and the weather. This guide walks you past every one of them, in the order you will meet them.
01
The one rule before you open a bag
The simple habit that saves most first pours.
02
A bag calculator with a worked example
Work out exactly how much premix your top needs, so you buy once.
03
Thickness, weight and joins
A weight table for 20 to 40 mm tops, and where to put a join so it disappears.
04
Why cut-outs are where benchtops crack
How to shape and reinforce the corners around your sink and cooktop.
05
A mould that gives a glass-smooth face
Melamine, silicone and knock-outs, step by step with diagrams.
06
The face coat timing test
Judge it by how it looks, not the clock, and avoid hollow spots.
07
Sealing without roller lines
The two-roller method for an even, durable finish.
08
18 defects, their causes and fixes
From pinholes and crazing to two pieces in two shades.
09
Adding colour
A simple sample method so the finished top matches the colour you picked.
10
The other way
Pouring face up or in place on the cabinets, with a hand-trowelled finish.
The MACt Concrete Benchtop Kit: Starter vs Ultimate
Everything the mix needs except water, plus the sealer. Grey premix for the classic raw-concrete look, or white for a brighter finish and the best base for colour. Live prices from our online store.
MACt Benchtop Starter Kit
From
$765.05 Inc GST
10 bags of Silica-Free Premix with the plasticiser, both fibres and MACt Seal. Covers up to 4 m² at 25 mm.
MACt Ultimate Benchtop Kit
From
$1,530.10 Inc GST
20 bags with double the fibre and sealer, for a full kitchen. Covers up to 8 m² at 25 mm.
| In the box | Starter | Ultimate |
|---|---|---|
| Covers, at 25 mm thick | up to 4 m² | up to 8 m² |
| MACt GFRC Premix, Silica-Free, 20 kg bags | 10 bags | 20 bags |
| MACt Plasticiser | 1 kg | 1 kg |
| 3 mm HD glass fibre (face coat) | 1 kg | 2 × 1 kg |
| 13 mm AR glass fibre (strength) | 5 kg | 2 × 5 kg |
| MACt Seal | 1 L | 2 × 1 L |
Bigger top? Send us your sizes at sales@mact.au and we will add bags and put the whole list together. Ask us about upgrading the kit sealer to Trinic H13, our recommended benchtop sealer. Free pick-up from our Banyo warehouse, 7:30 am to 3:30 pm weekdays, or delivery Australia-wide.
Free GFRC Mix Calculator
Work Out Your Benchtop Before You Buy
Enter your benchtop, drop edge and cut-outs. The calculator works out the premix, the mixes, the mould and whether a Benchtop Kit covers it.
- Bags of premix for every piece, rounded up
- Face coat and backing mixes, weighed out batch by batch
- A 3D view, plan and mould cutting list
- Your shopping list at today’s prices: add it all to your cart in one go
Example from the calculator
Benchtop
2,400 × 600 × 25 mm
Silica-Free Premix, 20 kg bags
4 bags
Water for the whole job
11.2 L
Each piece weighs about
83 kg
Plus the mixes for every batch, the mould cutting list, a 3D view and your shopping list at today’s prices.
How to Make a DIY Concrete Benchtop in 7 Steps
1
Plan
Measure up, build a template on your cabinets, and decide the joins and cut-outs before you buy.
2
Build the mould
Cut the melamine, screw it together and silicone every inside corner. The silicone cures 24 to 48 hours.
3
Mix and pour
A thin face coat, then the fibre-reinforced backing, then cover it. At least 24 hours in the mould.
4
Demould
When it passes the fingernail and tap tests, lift it out and stand it with air all round it.
5
Finish
Fill any pinholes, sand and clean. Best left about a week before sealing.
6
Seal
5 to 6 thin coats, each one dry before the next. Fully cured at 7 days.
7
Install
Support it everywhere on packers and fix it flexibly. Treat it gently until day 7.
Most of the time is waiting: for the silicone, the concrete and the sealer. Allow about two weeks from building the mould to installing your top. The eBook covers every step in full.
Made with MACt Premix
A kitchen benchtop, a double vanity, a boardroom table and a pedestal basin, cast by MACt customers with the same premix that comes in the kit.
DIY Concrete Benchtop FAQs
How thick should a DIY concrete benchtop be?
At least 20 mm, and 25 mm is typical for a kitchen. For a chunkier 60 or 100 mm look, cast a drop edge to that depth, or cast the whole top at that thickness.
How heavy is a concrete benchtop?
At 25 mm thick, a GFRC benchtop weighs about 57 kg per square metre. A standard 2.4 m × 0.6 m run is around 83 kg, so plan for at least two people and check the path into the room before you cast.
How many bags of premix do I need?
At 25 mm thick, each 20 kg bag of MACt GFRC Premix covers about 0.41 m². The Starter Kit covers up to 4 m² and the Ultimate Kit up to 8 m². The eBook includes a worked example, and our GFRC Mix Calculator works it out from your sizes.
How long does it take to make a concrete benchtop?
Allow about two weeks from building the mould to installing the top. The hands-on work fits into a few sessions; most of the time is the concrete curing and drying before it is sealed.
Will my concrete benchtop crack?
Most cracks start at square inside corners around cut-outs, or in a top that rocks or is glued down rigidly. Rounded corners, glass rebar around the openings, packers under the top and flexible fixing prevent them. The eBook covers each one.
How do I seal a concrete benchtop?
With thin coats of sealer, rolled on once the top is fully dry: best about a week after the pour, each coat dry before the next. The kit includes MACt Seal, and Trinic H13 is our recommended upgrade for benchtops.
Can I make a white or coloured concrete benchtop?
Yes. White premix gives a brighter finish and is the best base for colour. Oxide is mixed through the whole batch, so it cannot wear off an edge or corner.
Can I pour a concrete benchtop in place on the cabinets?
Yes. The eBook includes a section on the other way: pouring face up, on the bench or in place, with a hand-trowelled finish.
Ask Us Before the Pour
We would much rather answer a question before the pour than after it.
Phone
07 3111 4047
sales@mact.au
Pick-up
Banyo, 7:30 to 3:30 weekdays
Delivery
Australia-wide
Your Concrete Benchtop Starts on Paper
Plan it first. Measure up, make a template and decide the joins and cut-outs before you buy.
Work it out. Our GFRC Mix Calculator gives you the bags, the mixes and the mould cutting list.
Then call us. Send your sizes and we will check them and put your list together.
Get the free 41-page guide
Get the eBook, then call us before the pour: 07 3111 4047.