{"title":"Concrete, Cement \u0026 Bonding Agents","description":"\u003ch2\u003eConcrete for Retaining Walls — Post Footings, Rapid Set \u0026amp; Cement Mix\u003c\/h2\u003e\u003cp\u003eChoosing the right concrete for a retaining wall is one of the most critical decisions in the build. The concrete sets your steel posts in place and carries the lateral load of the retained soil — undersized or poorly mixed footings are the leading cause of post movement and wall failure over time.\u003c\/p\u003e\u003cp\u003eOur concrete, cement, and bonding agent range is selected specifically for retaining wall applications — rapid-set concrete for post footings, standard concrete for larger pours, and bonding agents for repairs. Trade and DIY quantities available with Australia-wide delivery.\u003c\/p\u003e\u003ch2\u003eWhat Concrete to Use for a Retaining Wall\u003c\/h2\u003e\u003cp\u003eFor standard residential retaining wall post footings, use a minimum 20MPa rapid-set concrete mix. Key guidelines:\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eMinimum \u003cstrong\u003e20MPa concrete\u003c\/strong\u003e for all post footings\u003c\/li\u003e\n\u003cli\u003eFooting depth: minimum one-third of total post length (deeper on soft, wet, or expansive soils)\u003c\/li\u003e\n\u003cli\u003eFooting diameter: typically 300–450mm depending on post size and wall height\u003c\/li\u003e\n\u003cli\u003eAllow full cure (minimum 24–48 hours) before backfilling and loading the wall\u003c\/li\u003e\n\u003cli\u003eWalls over 1.0m or on reactive clay: consult a structural engineer for footing design\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eProducts in This Range\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRapid-set concrete\u003c\/strong\u003e — ideal for retaining wall post footings where you need to continue work quickly. Sets firm within 20–30 minutes\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard concrete mix\u003c\/strong\u003e — for larger pours or where extended working time is needed\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCement \u0026amp; sand\u003c\/strong\u003e — for custom batching on larger projects\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBonding agents\u003c\/strong\u003e — for repairs, patching, and bonding new concrete to existing surfaces\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatible Post Systems\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\u003ca href=\"\/collections\/h-beam-uc-steel-posts\"\u003eH-Beam \u0026amp; Universal Column steel posts\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/collections\/c-channel-pfc-steel-posts\"\u003eC-Channel \u0026amp; PFC steel posts\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"\/collections\/corner-l-posts-joiner-end-posts-rwd\"\u003eCorner, L-posts, joiner \u0026amp; end posts\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eComplete Your Wall System\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/drainage-kits-ag-pipe-weep-holes\"\u003eDrainage kits, ag pipe \u0026amp; weep holes\u003c\/a\u003e — essential for long-term wall performance\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/hardware-brackets-cleats-rwd\"\u003eRetaining wall brackets \u0026amp; hardware\u003c\/a\u003e — fixings to complete the installation\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"\/collections\/retaining-wall-kits-bundles\"\u003eRetaining wall kits\u003c\/a\u003e — sleepers, posts \u0026amp; drainage in one order\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eNot sure how much concrete you need for your retaining wall footings? \u003ca href=\"\/pages\/retaining-wall-calculator\"\u003eUse our Material Estimator\u003c\/a\u003e or \u003ca href=\"\/pages\/contact-retaining-wall-direct\"\u003econtact our team\u003c\/a\u003e for a free estimate.\u003c\/p\u003e","products":[{"product_id":"rapid-set-bags-20kg-25mpa","title":"RAPID SET Bags 20kg 25mpa","description":"\u003cp\u003e\u003cstrong\u003eRapid set is a fast-setting 20kg concrete (25 MPa) for setting posts quickly — ideal for retaining wall steel posts, fence posts and letterboxes.\u003c\/strong\u003e Just add water in the hole; sets in minutes. Delivered Australia-wide by Retaining Walls Direct.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eWritten and product-checked by the Retaining Walls Direct team — supplying retaining wall and fencing materials across Australia. Last updated: June 2026.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eRapid set 20kg 25MPa\u003c\/h2\u003e\n\u003cp\u003eThe go-to for setting \u003ca href=\"\/collections\/steel-posts\"\u003eretaining wall steel posts\u003c\/a\u003e when you want to keep moving — 25 MPa strength with a fast cure. For general non-urgent posts, our \u003ca href=\"\/products\/post-mix-bags-20kg\"\u003epost mix\u003c\/a\u003e is a budget alternative.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eSize\u003c\/th\u003e\n\u003ctd\u003e20kg bag\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eStrength\u003c\/th\u003e\n\u003ctd\u003e25 MPa\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSet\u003c\/th\u003e\n\u003ctd\u003eFast-setting (minutes)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eUse\u003c\/th\u003e\n\u003ctd\u003eRetaining wall posts, fence posts, letterboxes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eRetaining Walls Direct\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eBuying with confidence\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAustralia-wide delivery\u003c\/strong\u003e with a same-day freight quote.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGoogle-reviewed service\u003c\/strong\u003e and trade support.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReturns:\u003c\/strong\u003e see our \u003ca href=\"\/pages\/returns-delivery-refund-policy\"\u003ereturns \u0026amp; delivery policy\u003c\/a\u003e.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003ca href=\"\/pages\/book-a-quote\"\u003eGet a quote\u003c\/a\u003e or \u003ca href=\"\/pages\/contact-retaining-wall-direct\"\u003econtact the team\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently asked questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eHow fast does it set?\u003c\/strong\u003e\u003cbr\u003eWithin minutes — ideal for setting posts without long waits.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow many bags per post?\u003c\/strong\u003e\u003cbr\u003eAllow 1–2 bags per post depending on hole size and depth.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan you deliver to me?\u003c\/strong\u003e\u003cbr\u003eWe deliver across most of Australia. \u003ca href=\"\/pages\/book-a-quote\"\u003eSend your details\u003c\/a\u003e for a quote.\u003c\/p\u003e","brand":"Retaining Walls Direct","offers":[{"title":"Default Title","offer_id":52288012058904,"sku":"RAPID","price":18.95,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0952\/5595\/3688\/files\/rapid-set-concrete-20kg-25mpa.webp?v=1782364746"},{"product_id":"post-mix-bags-20kg","title":"Post Mix Bags 20kg","description":"\u003cp\u003e\u003cstrong\u003ePost mix is a premixed 20kg concrete for setting fence posts, letterboxes, clothes lines and garden posts — just add water in the hole.\u003c\/strong\u003e Approx. 10L yield per bag. Delivered Australia-wide by Retaining Walls Direct.\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eWritten and product-checked by the Retaining Walls Direct team — supplying retaining wall and fencing materials across Australia. Last updated: June 2026.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003ePost mix 20kg\u003c\/h2\u003e\n\u003cp\u003eA convenient premixed concrete for post-setting jobs around the home and on site. For setting \u003ca href=\"\/collections\/steel-posts\"\u003eretaining wall steel posts\u003c\/a\u003e in a hurry, see our fast-setting \u003ca href=\"\/products\/rapid-set-bags-20kg-25mpa\"\u003erapid set\u003c\/a\u003e instead.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eSize\u003c\/th\u003e\n\u003ctd\u003e20kg bag\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eYield\u003c\/th\u003e\n\u003ctd\u003eApprox. 10L per bag\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eUse\u003c\/th\u003e\n\u003ctd\u003eFence posts, letterboxes, clothes lines, garden posts\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eRetaining Walls Direct\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eBuying with confidence\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eAustralia-wide delivery\u003c\/strong\u003e with a same-day freight quote.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGoogle-reviewed service\u003c\/strong\u003e and trade support.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReturns:\u003c\/strong\u003e see our \u003ca href=\"\/pages\/returns-delivery-refund-policy\"\u003ereturns \u0026amp; delivery policy\u003c\/a\u003e.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003ca href=\"\/pages\/book-a-quote\"\u003eGet a quote\u003c\/a\u003e or \u003ca href=\"\/pages\/contact-retaining-wall-direct\"\u003econtact the team\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently asked questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eHow much does one bag set?\u003c\/strong\u003e\u003cbr\u003eAbout 10L — roughly one standard post hole; check your hole size.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePost mix or rapid set?\u003c\/strong\u003e\u003cbr\u003ePost mix for general posts; rapid set when you need it to set fast (e.g. retaining wall posts).\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan you deliver to me?\u003c\/strong\u003e\u003cbr\u003eWe deliver across most of Australia. \u003ca href=\"\/pages\/book-a-quote\"\u003eSend your details\u003c\/a\u003e for a quote.\u003c\/p\u003e","brand":"Retaining Walls Direct","offers":[{"title":"Default Title","offer_id":52288018907416,"sku":"POSTMIX","price":15.95,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0952\/5595\/3688\/files\/post-mix-20kg-concrete-fence-posts.webp?v=1782364746"},{"product_id":"concrete-for-retaining-wall-post-footings","title":"Concrete for Retaining Wall Post Footings","description":"\u003ch2\u003eConcrete for Retaining Wall Post Footings\u003c\/h2\u003e\n\u003cp\u003eEvery steel retaining wall post needs to be set in concrete footings — and getting the concrete specification right is as important as getting the post size right. Undersized or poorly mixed footings are one of the leading causes of post movement and wall lean over time.\u003c\/p\u003e\n\u003cp\u003eWe supply 20MPa concrete mix for retaining wall post footings in two formats — \u003cstrong\u003ebags\u003c\/strong\u003e for small projects and top-up quantities, and \u003cstrong\u003eby the cubic metre\u003c\/strong\u003e for larger jobs where ordering in bulk is more economical.\u003c\/p\u003e\n\u003ch3\u003eHow Much Concrete Do You Need?\u003c\/h3\u003e\n\u003cp\u003eEach post footing typically requires 0.05–0.12m³ of concrete depending on post size and wall height. Use our \u003ca href=\"\/pages\/retaining-wall-calculator\"\u003eWallWise Pro calculator\u003c\/a\u003e to get an accurate concrete volume for your wall. As a rough guide:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e100 Series post\u003c\/strong\u003e — approx. 0.05m³ per footing (300mm diameter × 600mm deep)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e150 Series post\u003c\/strong\u003e — approx. 0.08m³ per footing (350mm diameter × 750mm deep)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e200 Series post\u003c\/strong\u003e — approx. 0.12m³ per footing (400mm diameter × 900mm deep)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSpecification\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eMinimum 20MPa compressive strength for all post footings\u003c\/li\u003e\n\u003cli\u003eAllow 24–48 hours minimum cure before backfilling and loading the wall\u003c\/li\u003e\n\u003cli\u003eFor walls over 1.0m or on reactive clay: consult a structural engineer for footing design\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003ePair with \u003ca href=\"\/collections\/steel-posts\"\u003egalvanised steel posts\u003c\/a\u003e and our \u003ca href=\"\/collections\/retaining-wall-kits-bundles\"\u003eretaining wall kits\u003c\/a\u003e.\u003c\/p\u003e","brand":"Retaining Walls Direct","offers":[{"title":"20kg Bag","offer_id":52321685504280,"sku":"CONC-20KG","price":18.11,"currency_code":"AUD","in_stock":true},{"title":"1m³ (Cubic Metre)","offer_id":52321685537048,"sku":"CONC-1M3","price":280.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0952\/5595\/3688\/files\/concrete-for-retaining-wall-post-footings-from-a-concrete-truck-or-by-the-20kg-bag-for-concrete-sleeper-retaining-wall.png?v=1782288602"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0952\/5595\/3688\/collections\/QPro_2025_RapidSetBags_20kg_25mpa-600x600.webp?v=1781695278","url":"https:\/\/www.retainingwallsdirect.com.au\/collections\/concrete-cement-bonding-agents.oembed","provider":"Retaining Walls Direct","version":"1.0","type":"link"}