FRP powder

PROPERTIES OF AUTOCLAVED CEMENT PASTE CONTAINING SCRAP FRP POWDER... 

One of the effective treatment of recycling method for scrap fiber reinforced plastic (FRP) is pulverization. The properties of the cement mortar containing the pulverized scrap FRP powder, cured in normal condition are reported in some papers [1], [2], [3],... 

Ordinary portland cement as specified in JIS R 5210 (Portland Cement), silica stone powder, scrap FRP powder and scrap glass powder were used, their properties are shown in Table 1 to Table 4, respectively. Particle size distribution curve for scrap FRP and glass powder are illustrated in Fig. 1. 

According to JIS R 5201 (Physical testing method for cement), cement pastes were prepared with the mix proportions in Table 5 (series 1) and Table 6 (series 2). Cement ratios to cement plus silica stone powder (cement content) were 30,40 and 50%, and water/cement ratios were constant at 50%. The scrap FRP powder was used as a filler, and the percentages of addition were 5, 10 and 15% in this study. 

Fig.2 shows the effect of addition of scrap FRP powder on the compressive and flexural strengths. Although both compressive and flexural strengths at 5 to 10% of scrap FRP powder addition shows a tendency to be smaller than those of plain paste, those at 15% is larger than those at 5 to 10%. When the cement content is 50%, the largest compressive and flexural strengths are gained. 

Fig. 3 shows the relationship between percentage of scrap FRP powder addition and bulk specific gravity. It shows a similar tendency to the above-mentioned relationship in Fig. 2. There exists an obvious quantitative relationship between bulk specific gravity and strengths as shown in Fig. 4.

Fig. 3 The relationship between scrap FRP powder addition and bulk specific gravity...

FRP Powder Summaries of Technical Papers of Annual Meeting Architectural Institute of Japan, Sept. 1994, pp. 137-138... 

FRP is now enormously used and recycling as cementitious materials is paid attention. The purpose of this paper is revealing fundamental flexural properties of cementitious composites including FRP powder. 

Three composites including 9.1% (PAO), 13.3% (PA1) and 22.8% (PA3) of FRP powder to all powdery materials were extruded to rectangular shape (15 mm><40 mm) specimens. Furthermore two composites including 9.1% of A3 silica sand (PAO) and no aggregates (PA) were extruded as the references. 

Autoclave-cured specimens including FRP powder do not show superiority in flexural strength while water-cured specimens including 9.1% of FRP powder indicate excellent strength. 

Keywords asbestos-free mortar, autoclave curing, extrude, flexural strength, FRP powder, porosity, water curing... 

Chemical composition of FRP powder is shown in Table 2. DTA (differential thermal analysis) and TG (thermogravimetric analysis) versus temperature is shown in Fig. 1, which indicate combustion of resin at 350-450 degree Cels. 

Distribution of grain size is shown in Fig. 2 indicating the profile looks mostly like A3 silica sand. Main features of FRP powder are shown in Table 3. SEM photographs of FRP powder and A3 silica sand are shown in Fig. 3 and Fig. 4 (see next page). They look similar each other except that FRP powder includes many broken fibers (50- 500 micrometers) of GF. 

The five compositions examined are given in Table 4. All of the compositions are determined based on the total powdery materials weight of cement, silica powder, silica sand and powdered FRP. Weight of pulp, methyl cellulose (MC) and water of all compositions are 2%, 1.4% and 26.1% to all powdery materials respectively. Weight of cement of all compositions is 47.3% to all powdery materials. PA composite does not contain any other material. On the other hand PAO composite contains 9.1 % of silica sand. PA1, PA2 and PA3 composites contain 9.1%, 13.3% and 22. 8% of FRP powder, respectively. 

Average pore diameter of all composites that contain FRP powder increased in accordance with the FRP content. The ratio of pore surface of autoclave-cured specimens to water-cured ones decreased in accordance with FRP content ratio, which may indicate emergence of coarse hydration products or generation of bigger pores in case of autoclave-curing. (See Table 7)... 

Fig. 10 shows a fractured surface of autoclave-cured PAO composite and Fig. 11 shows one of autoclave-cured PA1. There appears smooth surface of A3 silica sand or FRP powder, which may suggest the same effect to multiple cracks in the early stage of bending. 

Bulk density (BD) of specimens of all composites is shown in Fig. 12. BD of all composites decreased in accordance with FRP content. It might be caused because a part of cement was replaced by FRP powder in the mix proportions used in this study. 

Flexural strength of autoclave-cured specimens shows a drastic drop by including FRP powder (see Fig. 13). PA that contains only fine powder as pozzolanic materials shows the highest flexural strength. PAO that contains silica sand locates the next. 

On the other hand, the order of strength in the case of water-cured specimens differs from that of autoclave-cured specimens. PA1 shows highest flexural strength. The increase of FRP content means decrease of flexural strength in this case, too. However, PA and PAO that contain no FRP powder indicate lower strength. 

Flexural strength of all water-cured specimens showed lower strength than that of autoclave-cuned ones except PA1. This exception may be caused by the reinforcing effect of GF, only when the content of FRP powder is... 

Main chemical component of FRP powder is inorganic oxide such as Si02 and CaC03 derived from GF and filler. There exists no particular difficulties to use FRP powder for the mix proportion in the range shown in Table 4 from the standpoint of flexural strength. 

The grain size of FRP powder is similar to A3 silica sand, which shows no difficulty in extruding. However extrudability decreases in accordance with FRP content. 

FRP powder inevitably contains GF. The curing condition that does not degrade GF can bring high strength as observed water-cured PA1, though durability problem should be considered. 

Moreover the smooth surface of FRP powder can bring small dispersed notches into brittle cementitious material that may produce slightly high strength. However, the effect was not confirmed in this work. 

In spite of low tapped bulk density, apparent density of FRP powder is not low compared with silica sand. Therefore FRP powder itself can not make BD of hydrated composite much lighter. 

FRP powder decreases flexural strength and modulus of elasticity but increases water absorption ratio in all cases. It may lead to durability problems. 

Cementitious composites including FRP powder that was mainly composed of unsaturated-polyester resin, CaC03 (filler of FRP) and GF (reinforcement of FRP) were investigated. The grain size of FRP powder is similar to A3 silica sand. These suggest FRP powder to use as a substitute of A3 silica sand to extrudable composite. 

If specimens are cured in the autoclave, the strength of composites including FRP powder drastically dropped to the level of water-cured specimens. 

If specimens are cured in water, the composite including 9.1 % of FRP powder showed the maximum strength among all composites. It was suggested that the result comes from reinforce effect of GF in FRP powder. 

In all composites investigated in this work, increasing the volume content of FRP powder decreased flexural strength, flexural modulus of elasticity and increased water absorption ratio. 

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