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The influence of several kinds of ultrafine powders (UFPs) of mineral admixtures on the fluidity and strength of cement paste have been studied. Experiments show that silica fume and UFPs of natural zeolite have a filling effect and little dispersing effect on the fluidity of cement paste; UFPs of phosphorous slag and blastfurnace slag have both a filling effect and a dispersing effect. Both kinds of UFP have a strengthening effect. Adding UFP and superplasticizer simultaneously leads to better filling and dispersing effects in cement paste, because the particles of UFP cannot fill in the cement floc effectively unless the self-coagulation of the UFP is destroyed by adsorbing superplasticizer. The strengthening effect of UFP is due to its densifying effect and chemical activity, as well as its capacity to modify the pore structure.

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Zeolitic mineral admixture (ZMA) is made of the finely divided powder of natural zeolite with a bit of other agent such as triethanolamine. When ZMA is used to displace about 10% (by mass) of the ordinary portland cement (OPC) (strength grade No. 525) in concrete and mixed with a suitable amount of superplasticizer (W/C = 0.31 to 0.35), then a high-strength concrete with compressive strength of about 80 MPa and a slump of about 180 mm can be obtained. The strength of this concrete is about 10 to 15% higher than that of the corresponding concrete mixed with pure OPC, and its bleeding decreases greatly. It also results in no segregation or separation of the mix, and thus it satisfies the requirement of pumping concrete in construction. The ZMA is suitable not only for the OPC but also for the slag portland cement. The strengthening effect of the ZMA is somewhat similar to that of silica fume. But the cost is only two thirds that of OPC. Thus, when ZMA is used to displace a certain amount of the cement in the concrete, the cost of the concrete thus made will be 3 to 5% cheaper than that of the corresponding concrete with pure cement. The ZMA can increase the amount of micropores (d < 625 Å) and decrease the amount of harmful large pores (d > 938 Å) in the cement paste. Hence, the strength of concrete is increased and its other properties are also improved. Furthermore, ZMA can raise the SiO2/CaO weight ratio in the transition zone to increase its C-S-H phase and decrease its calcium hydroxide content. Thus, the structure of the transition zone is improved. Consequently, the strength and resistance to permeability of the concrete are increased.

When the natural zeolite ceramsite (NZC) is added to cellular concrete, using the natural-zeolite powder as a gas carrier, natural-zeolite ceramsite cellular concrete is formed. It is a new type of concrete. Its compressive strength at 28 days is 12–14 MPa, while its density is 900–1000 kg/m3. It has a double capillary structure of cellular concrete and ceramsite. The NZC absorbs water and its capillaries are full of water when the concrete is mixed. But after concrete hardening, the capillaries in the NZC undergo ‘self-vaccumization’ owing to dehydration, so that the adhesion between the ceramsite and cellular concrete is increased.