Fundamnetals Of Concrete: Complete Technical Guide

The fundamentals of concrete are the bridge between the cement plant and the construction site: the concrete is the finished product of the whole cement industry, and the cement engineer who understands the concrete understands the customer: the composition, the water-cement ratio, the hydration, the strength, the durability and the testing: the guide of the package teaches the physics and the chemistry that decide the life of every structure: the professional of the cement plant meets the concrete in the quality discussions, the technical service and the sales.

The Complete Cement Technical Package (931 files: the books, the courses, the Excel tools and the presentations: $249.99 one-time: instant download via the PayPal payment) includes this concrete fundamentals file with its tables of the mixes, the test procedures and the property charts: this article walks the file chapter by chapter: the reader acquires the vocabulary, the quantitative laws and the field wisdom of the concrete technology: the beginner gets the map, the professional gets the numbers.

This page is organized exactly as the document: the definitions and the constituents first, the hydration chemistry second, the mix design third, the properties fourth, the durability and the testing last: every section of the page mirrors the section of the file: the operator, the engineer and the manager all find their level here: the reading concludes with the questions that the file answers in its appendix.

1. The Constituents of the Concrete: The Recipe of the Building

The concrete is a composite: the binder paste holds the aggregates together: the four constituents of every mix: the cement, the water, the fine aggregate (sand) and the coarse aggregate (gravel): in addition the modern concretes carry the chemical admixtures and the mineral additions: the proportions decide everything.

• The cement: the hydraulic binder of Portland type: the CEM I ordinary, the CEM II composite, the CEM III blast furnace, the CEM IV pozzolanic and the CEM V composite: the cement type selection is the first design decision;
• The water: the mixing water of the hydration: the potable quality rule: the total water content divided by the cement content: the water-cement ratio: the single most important number of the concrete;
• The fine aggregate: the sand of 0 to 4 mm: the grading of the fractions and the cleanliness: the fines below 0.125 mm: the quality of the sand affects the workability and the strength;
• The coarse aggregate: the crushed stone or the gravel of 4 to 32 mm: the grading, the shape, the crushing strength: the aggregate occupies 60 to 75 percent of the volume of the concrete;
• The admixtures: the superplasticizers, the retarders, the accelerators, the air entrainers: the small doses (0.2-2 percent of the cement) modify the workability, the setting and the frost resistance;

The proportions of a typical structural concrete: cement 300 to 350 kg/m3, water 150 to 180 liter, sand 700 to 800 kg, gravel 1,000 to 1,100 kg: the ratios of weight about 1 : 0.5 : 2.2 : 3.2: the file carries the complete mix tables for the grades from C12/15 (the lean fill) to C50/60 (the high strength): the recipe is the balance sheet of the masses and the engineer of the ready-mix is the bookkeeper.

Concrete grade	Cement (kg/m3)	w/c ratio	Typical use
C12/15	200 – 260	0.65 – 0.75	lean fill, blinding
C20/25	260 – 320	0.55 – 0.65	general structures
C30/37	320 – 380	0.45 – 0.55	bridges, high-rise
C40/50	380 – 450	0.38 – 0.45	prestressed
C50/60	430 – 500	0.32 – 0.40	special high-strength

The proportions are the raw mix of the concrete, and the same logic as the raw mix of the kiln: the trial mixes in the laboratory verify the recipe against the strength and the workability: the standards of the industry (the EN 206 and the equivalent system) govern the classes and the testing: the file gives the table of the standard mixes.

2. The Hydration Chemistry: The Reaction of the Cement with the Water

The concrete gains its strength from the hydration: the cement reacts with the water in the exothermic process that forms the cementitious gel: the chemistry of the hydration belongs to the cement plant and the concrete guide recaps the fundamentals:

• The clinker phases: the alite (C3S) hydrates fast and gives the early strength: the belite (C2S) hydrates slowly and gives the late strength: the aluminate (C3A) reacts fiercely with the water and needs the gypsum regulation: the ferrite (C4AF) contributes the little:
• The hydration products: the CSH gel: the main binder of the concrete, the calcium hydroxide (portlandite) and the ettringite: the composition of the paste that fills the space between the aggregates:
• The heat of hydration: 250 to 400 kJ/kg of the cement: the mass concrete of the dams and the foundations risks the thermal cracking: the low-heat cements and the temperature control of the file:
• The degree of hydration: 20 to 40 percent of the cement hydrates in the first days, and the process continues for the months: the strength of the concrete is the hydrate building in the time:
• The capillary pores: the space of the originally filled with water: the lower the water-cement ratio the less the capillary porosity and the higher the strength and the durability:

The famous law of the file: the strength of the cement paste is governed by the water-cement ratio according to the well-known relationship: strength is inversely proportional to the w/c ratio: every 0.05 of the w/c reduction with the proper compaction raises the strength 5 to 10 MPa: the modern concretes of the w/c of 0.30 reach the double of the strength of the w/c 0.60: the hydration chemistry explains the numbers: the dark side of the high w/c is the porosity: each extra liter of the mixing water leaves its capillary hole in the paste when the excess evaporates: the microscope pictures of the file show the difference between the dense paste of the w/c 0.40 and the open sponge of the w/c 0.70: the lesson of the photographs is the lesson of the site: the water is the enemy of the strength in the same proportion it is the friend of the workability.

The temperature of the concrete is the second variable of the hydration kinetics: the rate of the hydration doubles roughly for every 10 degrees of the temperature rise within the normal range: the summer concrete of the 35 degrees sets and gains its early strength faster, but the rapid early hydration can consume the strength reserve of the later ages when the concrete dries: the winter concrete below 5 degrees almost stops hydrating and risks the frost damage of the fresh paste: the file explains the temperature-leaflet of the standard methods and the concrete the site controls: the temperature of the fresh concrete is measured, logged and managed because the hydration is a chemical reaction that obeys the temperature exactly like the kiln reactions of the plant.

3. The Water-Cement Ratio and the Workability

The water in the concrete mix plays two conflicting roles: it hydrates the cement and it lubricates the mix: the engineer balances the two in every mix design: the file teaches the dual life of the water:

• The hydration water: the stoichiometric water of the cement hydration is about 25 percent of the cement mass, but the practically hydrated concrete needs more: the excess water creates the capillary voids;
• The workability water: the paste must flow and the mixer must place and compact without the segregation: the slump test measures the workability: the water content is the traditional lever;
• The superplasticizers: the modern chemistry separates the two roles: the superplasticizer disperses the cement particles and restores the slump with a small water reduction of 20 to 30 percent: the high-performance concrete uses them;
• The slump classes: the S1 stiff (10-40 mm) to the S5 flowing (220 mm +) of the standards: the placements of the formwork, the pumping and the vibration demand the classes:
• The compaction: the concrete must be fully compacted into the form; the honeycomb and the voids destroy the strength: the vibration energy and the dosing of the file: the plastic theory of the compaction;

The professional’s view of the file: the slump is the measure of the fresh state and the w/c ratio is the measure of the hardened state: the site pushes for the water (the easy placement) and the plant resists (the strength): the modern truce: the superplasticizer solves the conflict: the file carries the dosage tables of the admixtures and the w/c of the standard mixes.

4. The Mix Design: The Procedures and the Calculations

The mix design is the calculation of the proportions of the constituents to achieve the target strength, the workability and the durability at the minimum cost: the file follows the classical design methods of the standards (the DOE method and its equivalents) with the full worked example:

• The targets: the characteristic strength of the grade, the slump class, the exposure class of the environment: the design inputs of the mix:
• The water content: from the workability and the aggregate properties: the tables of the file give the water demand per the slump and the max aggregate size:
• The cement content: divided by the water-cement ratio: the minimum cement of the standards and the durability classes also decide:
• The aggregate proportions: the combined grading of the coarse and the fine: the void content and the excess paste: the proportioning by the particle packing:
• The trial mixes: the laboratory batches verify the slump, the density and the 7 and 28 day strengths: the adjustment loops: the three trials of the file:

Worked example of the file: the C30/37 concrete: the slump S3: the max aggregate 20 mm: the file computes: the target mean strength 45 MPa (the characteristic + 8 MPA, the margin), the water-cement ratio 0.46 from the strength table, the water demand 175 liters, the cement 380 kg, the aggregate 1,850 kg with the sand/gravel split at the 45/55: the trial mix verifies: the file carries the full design sheet with the corrections in the appendix: the reader repeats the process with the local materials.

Step	Parameter	Example value	How derived
1	Target 28-day strength	31 MPa	grade + margin
2	w/c ratio	0.46	strength table
3	Water content	220 l/m3	workability table
4	Cement content	380 kg/m3	water / w/c
5	Aggregates	1,850 kg/m3	mass balance

The mix design is the daily arithmetic of the ready-mix plant and the site: the file’s tables and the calculator bring the design into the laptop of the engineer: the complete procedure: skip it at your own risk, the strength is not negotiated with the statistic.

5. The Strength of the Concrete: The Mechanics and the Testing

The strength of the concrete is the first answer that every designer asks: the compression strength, the bending strength and the tension strength are the mechanics of the material: the file explains the three and the testing methods:

• The compressive strength: the cube and the cylinder tests: the agreed standard: the cube of 150 mm side, the cylinder of 150 by 300 mm: the 28-day characteristic strength is the grade of the concrete: the strength of the file: the class C30/37 means the 30 MPa cylinder and the 37 MPa cube;
• The development curve: the strength grows with the age: the 1-day 20 to 30 percent, the 7-day 65 to 80 percent and the 28-day 100 percent of the class strength: the hydration continues beyond and adds 10 to 20 percent at the 90 days: the file table of the age factors;
• The flexural and the tensile strength: the compressive / 10 to 14 percent: the splitting test of the cylinder (Brazilian) and the bending test of the beam: the pavement and the precast design use the numbers:
• The elastic modulus: the stiffness of the concrete: 25 to 40 GPa: the relation with the strength and the density: the deflection of the structures:
• The testing: the specimens compacted, cured in the water bath at 20 deg C, and crushed on the calibrated press: the acceptance criteria of the standards: the mean and the minimum of the tests:

The standard discipline of the testing: the specimens of the samples: for each strength class and each day: the minimum sample of the job, the bridge of the site the numbers: the file carries the statistics of the testing: the strength, the coefficient of variation and the compliance: the acceptance is not a debate, the standard is the referee: the file teaches the complete method.

6. The Durability of the Concrete: The Enemy List

The durable concrete is the concrete that resists the environment for the design life of 50 to 100 years: the file lists the enemies of the concrete and the defensive measures:

• The reinforcement corrosion: the chloride from the sea and the de-icing salts, the carbonation of the cover concrete: the steel rusts, expands and cracks the cover: the corrosion starts at the moment the chlorides reach the steel: the concrete cover of 25 to 75 mm by the classes;
• The freeze-thaw: the water in the pores freezes, expands and cracks the concrete: the air-entrained concrete with the micro bubbles of 4 to 7 percent of the air: the resistant, frost; the salt scaling:
• The sulfate attack: the sulfates from the ground water and the sewage react with the aluminate and expand: the sulfate-resisting cement (the low C3A, below the 3-5 percent): the design measure:
• The alkali-silica reaction: the reactive silica of the aggregates reacts with the alkali pastes and produces the gel that expands: the crack the concrete: the prevention: the non-reactive aggregates, the cement class of the low alkali (the Na2O equivalent below 0.6 percent);
• The fire resistance: the concrete is the fire switch: the density, the moisture and the spalling at the extreme 400 to 800 deg C: the fire design of the file: the structures, the tunnels, the high-rise:

The durability is designed, not discovered: the water-cement ratio below 0.45, the cement content above 320 kg, the cover the right and the compaction full: the standard exposure classes X0 to XA map the environment to the prescriptions: the file carries the complete table of the exposure and the required proportions.

7. The Fresh Concrete: The Workability, the Setting and the Transport

The concrete spends its first hours in the fluid state and the handling of that window decides the quality of the hardened product: the fresh concrete of the file:

• The workability: the slump test at the site: the cone of 300 mm high, the slump of the wet: the classes S1-S5: the pumpability and the placing methods select the class: the water is measured by the slump, never by the eye;
• The setting time: the initial set at 2 to 6 hours and the final set before the 12 hours: the temperature of the site, the cement type and the retarders modify: the joints and the concreting sequence respect the setting;
• The temperature: the fresh concrete of 5 to 35 deg C: the hot weather accelerates the setting and the loss of the slump: the ice in the mix and the cold storage of the water: the winter protection and the insulators:
• The transport: the ready-mix truck, the pump and the chutes: the time limit 60 to 120 minutes between the mixing and the placing: the re-mixing the water at the site is prohibited: the batch ticket of the delivery:
• The placing and the compaction: the drop height and the segregation: the form vibration: the thick elements: the internal vibrators: the laying of the sequence: the compaction is the hidden strength:

The fresh concrete is a perishable product: its quality window is counted in hours and the logistics of the site must deliver within it: the file gives the complete field rules of the workability and the transport, the tables of the travelling distance and the mixing time: the reader absorbs the discipline that distinguishes the reliable site from the doubtful one.

8. The Curing: The Mother of the Strength

The strength of the concrete is won or lost mainly in the first week: the curing is the procedure that keeps the water in the matrix while the hydration proceeds: the file teaches the curing as the decisive craft:

• The principle: the hydration stops when the pores dry: the concrete must stay wet or the water sealed: the moisture and the temperature of the fresh element the first 7 days;
• The methods: the water ponding, the wet burlap, the plastic sheeting and the curing compounds: the choice by the geometry, the access and the climate: the complete comparison of the file:
• The duration: the minimum 7 days for the normal cement, 3 days for the rapid types and 14 days for the site concrete: the minimum of the standard tables: the longer the better up to the 28 days:
• The temperature: the curing in the heat: the steam curing of the precast accelerates the 28-day strength to the days: the autoclaving of the special: the temperature procedures of the precast industry:
• The quality checks: the maturity method: the strength of the concrete from the temperature history: the demolding of the specimens, the schedule of the construction: the early strength tests:

The saying in the file: the concrete that is placed is only the beginning, the cured concrete is the masterpiece: the site with the slack curing throws away the cement investment: the guide quantifies: the poorly cured concrete at 28 days can lose 20 to 40% of the potential strength compared with the cured: the numbers of the file matter.

9. The Quality Control of the Concrete: Samples, Tests and Statistics

The concrete quality is verified by the testing of the hardened specimens and the statistical evaluation: the file gives the complete assurance system of the ready-mix production and the construction:

• The sampling: the samples taken from the fresh concrete at the point of the delivery: the frequency of the standard: the samples per the 100 m3 or per the day, whichever the smaller: the identification of the sample:
• The specimens: the cubes and the cylinders made, cured and tested: the 7-day and the 28-day: the accepted mean: the machine calibration of the press:
• The statistical evaluation: the mean strength, the standard deviation and the characteristic strength: the criterion of the conformity: the margin of the strength and the cement: all the tables the file:
• The coefficient of variation: the CV of the well-run plant is 5 to 10 percent: the CV of the plant with the bad dosing 15-20: the audit of the production discipline: the optimization of the cement:
• The non-conformities: the strength below the mean: the investigation: the cores from the site: the load tests: the dispositions: the honest chain of the quality:

The quality control of the concrete is the mirror image of the cement quality control: the same statistical logic that the plant uses for the clinker strength applies to the concrete cubes: the file transfers the discipline: the mean, the standard deviation, the target margin: the quality culture of the two industries is literally one: the teams that collaborate produce the trust: the chain of the quality runs from the quarry of the cement plant through the ready-mix at the site and finishes at the tested cube in the laboratory of the constructor: every link of the chain adds its share of the variation and the file traces each contribution: the cement strength variation of the plant, the dosing accuracy of the mixer, the curing of the specimens and the testing machine of the laboratory: each stage contributes its percent and the total variation is the sum: the engineer who understands the chain knows exactly where the improvement is cheapest.

10. The Concrete in the Cement Plant: The Technical Service

The cement plant and the concrete are the same customer conversation: the technical service of the cement plant is the interface: the file devotes the chapter to the dialogue between the plant and the site:

• The cement certificates: the analyses of the clinker, the fineness, the setting, the soundness and the strength classes of the cement types: the customer reads the certificate: the plant issues it:
• The compatibility: the cement – admixture compatibility: the specific admixture of the same plant: the setting anomaly: the test program of the file:
• The heat of the mass: the mass foundations and the dams with the low-heat cements: the plant recommends the appropriate type: the CEM III for the large sections:
• The concrete reports: the trial mixes of the customer, the diagnostics of the failures: the core examination: the petrographic analysis: the complete service:
• The new products: the self-compacting concrete (SCC), the high-performance concrete (HPC) and the shotcrete: the cement of the plants and the formulas: the technical support of the file:

The concrete fundamentals give the cement sales engineer the language of the customer: when the customer complains the cement “is failing”, the true cause is very often the water-cement ratio, the curing or the aggregate: the engineer who reads the mixes and the tests protects the plant’s name: the file trains the exact professional: the liaison between the chemistry of the kiln and the physics of the element.

11. The Frequently Asked Questions About the Fundamentals of the Concrete

What is the water-cement ratio and why does everything depend on it?

The w/c ratio is the mass of the water divided by the mass of the cement: the average 0.5: the water gives the workability but leaves the pores: the lower the w/c (with the full compaction), the denser the paste, the higher the strength and the better the durability: the single number of the concrete with the greatest weight of all.

The 28-day strength: why the 28 days?

The hydration of the Portland cement is practically finished at the 28 days in most of the concrete (about 90 to 99 percent): the convention of the standard class: the industry describes the concrete by the 28-day characteristic value: the early ages predict the set at the earlier where the later tests confirm: the file reports.

Can I add the water to the mix truck at the site?

No: the water raises the w/c and drops the strength dramatically: the added water to the truck: added without the measured the real: the site crew is trained to refuse: the adjustment is the superplasticizer-driven in the plant: the file states the rule and the exception.

Why does the concrete crack?

The concrete cracks under the tension from the drying shrinkage, the temperature differences and the loads: the design of the reinforcement carries the tension: the control: the joints of the contraction, the curing and the reduced mix of the water, the file: crack control part.

Does the package include the concrete add-ins and the calculators?

Yes: the Complete Cement Technical Package includes the concrete mix design tool, the strength statistics sheet and the specimen log: the engineers design the mix and the schedule in minutes: the 931 files of the package: the design and the test tools.

12. The Future of the Concrete Technology

The concrete of the future is a low-carbon, high-performance material: the file closes the technical chapters with the directions:

• The cement-reduced mixes: the supplementary cementitious materials: the slag, the fly ash and the calcined clays substitute 30 to 50 percent of the clinker in the mix: the new countries of the file: the future of the industry;
• The carbon capture: the cement produced with the captured CO2 and the concrete conditioning at the recycled CO2: the first net-zero buildings: the demonstration plants of the world:
• The digital an concrete: the fresh concrete tracking: the sensor cubes and the maturity: the delivery quality in the digital: the mixes in the data:
• The additive manufacturing: the 3D printed concrete walls reduce the form and the wastage: the cement formulation of the print: the robot soldiers: the new future workers:

The fundamentals do not change: the hydration, the w/c and the durability: the modern tools apply the same physics: the engineer who masters the fundamentals selects the correct flux, and the file of the package: the fundamental and the future: the professional of the concrete beyond the trends: the global classic of the material of the future.

13. Final Words of the Guide

The concrete fundamentals: the recipe, the chemistry, the strength, the durability, the curing and the quality: the material of the skyscrapers, the bridges, the dams and the airports: the engineer of the cement plant and the well-prepared customer: the relation between the two: the concrete is one common language: this guide: the language school: the tables, the tests and the field lessons: the professional engineer leaves with the terms that make him the trusted expert of the site.

The Complete Cement Technical Package includes this concrete fundamentals file with the mix design, the test procedures, the durability tables and the calculators: the one-time 249.99 payment via PayPal: the instant download: the 931 files: the fundamental of the concrete: the cement: the construction: the professional: the complete library: the plant, the engineering: the cement complete.

This file is part of the Complete Cement Technical Package (931 files) available from cementequipment.org. Respective rights holders; library copy for the licensed single user.