The invention provides ‘thixotropy’ monitoring, by measuring the reversible, time-dependent reduction in viscosity occurring when concrete is subjected to mixing, and employs a mixing drum and conventional slump monitoring equipment as used on ready-mix trucks. In one embodiment, the drum is rotated until concrete is completely mixed; the speed is altered, such as by increasing it to a predetermined level; and the energy required to rotate the drum (ER) is monitored; the maximum (ER-MAX) and minimum (ER-MIN) values are recorded in computer memory; and these values are compared to pre-determined (target) values. Rheology factors (including viscosity, yield stress, and/or thixotropy) can be adjusted accordingly by adding liquid component(s) into the mix. This method, suitable for delivery of highly fluid concrete speed such as SCC, can involve transit and placement rheology targets during monitoring.