Mix design approach for high 28 days’ strength, high-volume, low-lime fly ash concrete

Abstract

Use of high-volume fly ash concrete (HVFAC) has to be encouraged in the construction industry for sustainability, by increasing the 28 days' strength of HVFAC. In India, presently the use of fly ash in concrete is insignificant. The lower consumption may be attributed to the lower quantity of lime in fly ash and the quality of fly ash. Suitably designed HVFAC can solve major problems of concrete construction, if sufficiently early strength can be achieved as required by the construction industry. In the present parametric study, an approach is proposed for achieving comparable 28 days' strength of HVFAC without fly ash. The proposed concrete used 45% less cement by mass and was cheaper by 20% than control concrete. The results also show that fly ash could increase compressive strength and ultrasonic pulse velocity of concrete by the internal curing effect.

Bloques de concreto con sustitución de residuos sólidos de polietileno de alta densidad

“…Después de 30 días de curado se observó que, tanto la resistencia a la compresión como el peso unitario ,se redujeron a medida que aumentaba el porcentaje de plástico para las cuatro relaciones de mezcla (Figura 1). Con base en estos resultados, y de acuerdo a lo señalado por Shirish [18] y las normas técnicas NTE INEN [20][21], el propósito de uso de las muestras se incluye en la Figura 2.…”

“…Justo después de sacarlos del molde, los materiales se sumergieron completamente en un tanque de curado durante 30 días; método recomendado por Akinyele y Ajede [17] al aplicar el tanque de curado UTC-0960 de metal con una temperatura media de control entre 38 y 40 o C con ±2 o C de precisión. Según Shirish [18] el curado de bloques de concreto con materiales anexos como plástico, cal, yeso, cenizas, entre otros, aplicando un tanque para curado grande con dimensiones de 800x1800x950 mm, puede desarrollarse con un tiempo prolongado entre 28 y 30 días, los cuales fueron usados durante el presente estudio.…”

Processed bottom ash for replacing fine aggregate in making high-volume fly ash concrete

“…Small particle size and the rounded shape of the fly ash particles improve the workability of the paste mix, resulting in a decrease in the water requirement. HVFA concrete has at least 50% fly ash replacing cement, low water content (~130 kg/m 3 ), and low water to cementitious ratio (w/cm < 0.4) [7,8]. The use of high-volume fly ash in making concrete would reduce the use of cement as well as reduce the water use required for bottom ash mixtures [9,10].…”