Rheological and mechanical behaviour of high volume fly ash cement grouts

The society is becoming increasingly more energy and environmentally conscientious, which has forced development of construction materials, which are both inexpensive and require very little energy to produce. One way of producing such materials is to utilize by-products of industrial processes. High-volume fly ash cement based grouts are tributary of such developements.This thesis outlines the results of a detailed study of the grain size distribution, three rheological properties and five mechanical properties of high-volume fly ash grouts (60% cement replacement for fly ash by weight) with or without the use of superplasticizers and/or anti-washout agents. The rheological properties are reported for eight water/cement + fly ash (water/solids) ratios. The effect of superplasticizers and anti-washout agents on the flow time of low water/solids ratio grouts and the stability of high water/solids ratio grouts are investigated.The study revealed that: (1) The addition of fly ash reduces significantly the flow time of low water/solids ratio grouts (0.4 to 0.65). (2) The stability of cement grout is improved by the addition of fly ash for water/solids ratios greater than or equal to 0.65. (3) The use of fly ash reduces the early compressive and bond strength, when compared to the reference grout (pure cement). However, as they mature their strengths are closer to those of the pure cement grouts. (4) Fly ash reduces the amount of drying shrinkage compared to pure cement grout with an equivalent water/solids ratio