Quantification of the strength development in early age concrete and its resistance to plastic shrinkage cracking

Early plastic shrinkage cracking of concrete is an important factor affecting the durability of modern concrete structures. Early cracking (within 24 hours after pouring) may become a problem for any concrete structure. It will promote the entry of harmful materials, destroy the beauty of concrete members, and reduce their durability and performance. In addition, due to long-term shrinkage and/or load, these cracks may gradually expand in the service life of components. Scientific research and engineering technicians often have to face the difficulties caused by early plastic shrinkage cracking of concrete. From the aspects of shrinkage mechanism, measurement method, prediction model and strength development, this paper reviews the scientific and technological status of plastic shrinkage and strength development of early-age concrete, and based on this, summarizes the important conclusions in existing research and establishes the relevant concrete strength prediction model.:1 Introduction 2. Shrinkage in concrete 2.1 Classification and mechanism of concrete shrinkage 2.2 Main factors causing concrete shrinkage 2.3 Concluding remarks 3. Plastic shrinkage in early age concrete 3.1 Method for determining the time of initial and final setting 3.2 Mechanism of plastic shrinkage 3.3 Evaporation 3.4 Capillary pressure 3.5 Main factors affecting plastic shrinkage cracking 3.6 Concluding remarks 4. Different methods for determining the resistance to plastic shrinkage cracking 4.1 Rectangular mould test setup 4.2 ASTM C 1579 4.3 Ring test method (NT BUILD 433) 4.4 Capillary pressure test 5. Development of early age strength of concrete 5.1 Mechanical properties 5.1.1 Compressive strength 5.1.2 Tensile strength 5.1.3 Early-age shrinkage of concrete 5.2 Test and prediction model evaluation 6. Test and quantitative model 6.1 pullout tests on early-age concrete 6.1.1 Tests principle 6.1.2 test result 6.2 Compilation of existing pullout capacity prediction models 6.2.1 Strength and pullout force model based on 6.2.2 Strength and pullout force model based on and ∅ 6.2.3 Tensile strength and pullout force model 6.3 Application of existing prediction model in early age concrete 7. Conclusions 8. Literatur