Please enter valid positive numbers for all fields.
Rate of Rise (R):0 ft/hr
Total Volume Required:0 CY
Plan Area (Cross Section):0 sq. ft.
Estimated Pour Duration:0 hours
function calculatePourRate() {
// Get Inputs
var length = parseFloat(document.getElementById('wallLength').value);
var height = parseFloat(document.getElementById('wallHeight').value);
var thicknessInches = parseFloat(document.getElementById('wallThickness').value);
var deliveryRate = parseFloat(document.getElementById('deliveryRate').value);
var errorDiv = document.getElementById('errorMsg');
var resultsDiv = document.getElementById('results');
// Validation
if (isNaN(length) || isNaN(height) || isNaN(thicknessInches) || isNaN(deliveryRate) ||
length <= 0 || height <= 0 || thicknessInches <= 0 || deliveryRate <= 0) {
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
errorDiv.style.display = 'none';
// 1. Calculate Wall Thickness in Feet
var thicknessFeet = thicknessInches / 12;
// 2. Calculate Plan Area (Cross Sectional Area looking down)
// Area = Length * Thickness (converted to feet)
var planArea = length * thicknessFeet;
// 3. Calculate Rate of Rise (Pour Rate in Vertical Feet per Hour)
// Formula: R (ft/hr) = (Delivery Rate (CY/hr) * 27) / Plan Area (sq ft)
// We multiply by 27 to convert Cubic Yards to Cubic Feet
var riseRate = (deliveryRate * 27) / planArea;
// 4. Calculate Total Volume
// Volume (CY) = (Plan Area * Height) / 27
var totalVolumeCF = planArea * height;
var totalVolumeCY = totalVolumeCF / 27;
// 5. Calculate Time Duration
// Time = Total Volume / Delivery Rate
var duration = totalVolumeCY / deliveryRate;
// Update DOM
document.getElementById('riseRateResult').innerHTML = riseRate.toFixed(2) + ' ft/hr';
document.getElementById('totalVolumeResult').innerHTML = totalVolumeCY.toFixed(2) + ' CY';
document.getElementById('planAreaResult').innerHTML = planArea.toFixed(2) + ' sq. ft.';
// Format time to Hours and Minutes for clarity
var hours = Math.floor(duration);
var minutes = Math.round((duration – hours) * 60);
document.getElementById('timeResult').innerHTML = duration.toFixed(2) + ' hrs (' + hours + 'h ' + minutes + 'm)';
resultsDiv.style.display = 'block';
}
Understanding Concrete Pour Rate (Rate of Rise)
The Concrete Pour Rate, technically known as the rate of rise ($R$), is a critical variable in construction engineering and formwork design. It is defined as the vertical distance the concrete rises within the formwork over a period of one hour (feet per hour or meters per hour).
Unlike simple volume calculations, the pour rate determines the liquid head pressure exerted on the formwork walls. As concrete is poured faster, it remains in a liquid state for a greater vertical depth before setting, exerting higher pressure that can cause forms to burst (blowout) if not designed correctly according to ACI 347 standards.
Why is Pour Rate Critical?
Formwork Safety: Faster pours create higher lateral pressures. If the rate of rise exceeds the design limit of the formwork, catastrophic failure can occur.
Project Scheduling: Knowing the pour rate helps in planning the arrival of concrete mixers and pump trucks to ensure a cold joint does not form.
Quality Control: A consistent pour rate ensures better consolidation and finish of the concrete surface.
How to Calculate Pour Rate
The calculation is based on the relationship between the volumetric delivery rate of the concrete and the cross-sectional area of the element being poured (such as a wall or column).
The formula used in this calculator is:
R = (Q × 27) / A
Where:
R = Rate of rise (Vertical Feet per Hour).
Q = Concrete Placement Rate (Cubic Yards per Hour).
A = Plan Area of the wall or column (Square Feet).
27 = Conversion factor (Cubic Feet per Cubic Yard).
Example Calculation
Imagine you are pouring a foundation wall that is 50 feet long and 12 inches (1 foot) thick. You have a pump truck capable of delivering concrete at 30 cubic yards per hour.
Calculate Plan Area: 50 ft (length) × 1 ft (thickness) = 50 sq. ft.
In this scenario, the concrete level rises vertically at 16.2 feet every hour. The formwork designer must ensure the ties and bracing can withstand the pressure generated by liquid concrete rising at this specific speed.
Factors Affecting Pour Rate
While the math is straightforward, real-world conditions affect the actual pour rate:
Wall Thickness: Thinner walls fill up vertically much faster than thick walls for the same volume of concrete.
Truck Intervals: Delays between concrete mixer trucks reduce the effective hourly rate.
Weather (Temperature): In cold weather, concrete sets slower, increasing the effective liquid head pressure, often requiring a slower pour rate to maintain safety.
Admixtures: Retarders keep concrete liquid longer, while accelerators speed up setting. This changes the pressure calculations relative to the pour rate.